Around Florida: a brief treatise...
 Where in the World Wide Web?
 Faculty, staff, students, alumni,...
 Recent publications
 What happened?
 An event not to be missed
 Biotech briefs

Group Title: PLP news
Title: PLP news. Volume 4, Issue 4. Sept/Oct, 2000.
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067320/00016
 Material Information
Title: PLP news. Volume 4, Issue 4. Sept/Oct, 2000.
Series Title: PLP news
Physical Description: Serial
Creator: Plant Pathology Department, IFAS, University of Florida
Affiliation: University of Florida -- College of Agricultural and Life Sciences -- Plant Pathology Department -- Institute of Food and Agricultural Sciences
Publisher: Plant Pathology Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 2000
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067320
Volume ID: VID00016
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Around Florida: a brief treatise on the evolution of plant disease control in the peanut
        Page 1
        Page 2
        Page 3
    Where in the World Wide Web?
        Page 4
    Faculty, staff, students, alumni, and colleagues of our department
        Page 5
    Recent publications
        Page 6
    What happened?
        Page 7
    An event not to be missed
        Page 8
    Biotech briefs
        Page 9
        Page 10
Full Text

* Latest Publications
* Volunteering Around Town


* Faculty, staff, students and alumni
* CVC and the Xye/la fasildiosa Genome Project


From the Students of
the Plant P
Department to our com-
Volume 4 Issue 4
Sept-Oct 2000

Around Florida: A Brief Treatise on the Evolution of
Plant Disease Control in Peanut

By: Dr. ThomasA. Kucharek

The first evidence that some-
one was trying to minimize the impact
of a plant disease in peanut in Florida
Swas for peanut
leaf spot. This
work was pub-
lished by a Dis-
trict Extension
Agronomist, J. Lee Smith in 1953. He
published a summary of his work
within an Extension publication titled "
Tracks of Men, A Type of Agricultural
Extension History." In one section of
the publication, he summarizes his
work with 16 major peanut-producing
counties in Florida. He initiated doz-
ens of demonstration tests with grow-
ers beginning in 1940. He demon-
strated that the suppression of leaf
spot with sulfur dust resulted in yield
benefits that ranged from 120 to 305
lbs/A. While we would consider
these responses low by modern day
standards, with the types of disease
control programs that have evolved,
his studies were likely to have been the
reason that some growers related sup-
pression of leaf spot with increased
yields and monetary returns. Immedi-
ately after World War II, W.E. Stokes

and Fred Clark in the Agronomy De-
partment at the University of Florida,
conducted some tests with fungicidal
dusts and they attained similar results
to that of Smith.
It is not known when the first
identification of peanut leaf spot (PLS)
was made in Florida. Those involved
with peanut production in Florida in
the earlier part of this century probably
heard about and learned about this
disease directly or indirectly from h-
formation available from the Univer-
sity of Georgia and Auburn University
where studies on peanut diseases were
being conducted. The Plant Pathology
Department at the University of Flor-
ida had very little interaction with ag-
ronomic crop production in northern
Florida during the early to mid 1900s.
Vegetables and citrus were the tails that
l _d the dogs in those days. Now
we have too many tails and too many
Peanut leaf spot (PLS) is a
name of a complex that is composed
of early leaf spot, caused by Cercospora
arachidicola, and late leaf spot, caused by
Cercoporidium personatum. While both
have had their respective teliomorphic

stages described in the literature, nei-
ther teliomorphic stage has been seen
in over 40 years in the United States.
Over the years, many of us
working with peanut have learned that
PLS can cause extremely high yield
losses. In one test in Florida, a yield
loss of 91.8% resulted from PLS; this
is particularly high even in a test. Typi-
cally, in contemporary times within

cial fields,
from zero
to L' ..
occur, and in a few situations, yield
losses of 30 to 50% still occur.
During the 1960s and up to
1972 or so, most peanut growers in
Florida were using a few applications
of sulfur dust or sulfur dust combined
with a fungicidal copper dust (often
referred to as copper-sulfur) for sup-
pressing PLS. An avid research pro-
gram on disease control in peanut in
Florida began in 1968 by Dr. Carol
Miller, a research plant pathologist in
our department. His investigations

coincided with the advent of some
new fungicides such as benomyl,
chlorothalonil, and triphenyltin hydrox-
ide; he also evaluated mancozeb which
had been labeled since 1965.
In 1970, when I began as an
Extension Plant Pathologist, Dr. Miller
and I conducted numerous tests on
experiment station land at Marianna,
Florida and on commercial farms.
Naturally, the tests that had the greatest
"convincing power" for the growers
were those located on commercial
farms. The first thing we convinced
growers of was that they did not have
to use the messy dusts that covered
them (and us) from head to foot dur-
ing the application process with the
tractor-drawn dusting machines.
Moreover, the volume of dust that had
to be handled was as much as 20 to 25
lbs/A. Our tests demonstrated that
they could use Benlate as a spray, six to
seven times/season at 0.38 lb/A, and
achieve yield increases of over one
ton/acre when compared to the use of
20 lbs/A of Dithane M-45 (man-
cozeb) formulated as a dust. The ie-
sponses in yield we attained with dusts
when compared to the treatments
without any fungicide was similar to
that of J. Lee Smith. I can assure you
that when the growers came to field
days and looked at our results with the
new sprays in the early 1970s, they
were impressed, but they were very
suspicious of these "professors."
Growers told me repeatedly that such
a response could only occur on "Uni-
versity Land". Gradually, growers
bought sprayers, treated the crop, not
themselves, and ditched the dusters.
With the contemporary restoration
craze, at least one old Hudson Duster
has been restored for posterity.
Since those early tests, we have
had access to several new compounds
(e.g. new formulations of copper-
containing fungicides, strobilurins,
sterol biosynthesis inhibitors) and we


have learned how to use them. The
availability of a diverse array of chemi-
cals has allowed us to counter the
presence of resistant strains to Benlate
that occurred commonly by the mid
1970s. Benomyl (generic name of
Benlate) is a compound which has a
single site mode of action. However,
we must be vigilant with the use of
resistance management strategies be-
cause certain new fungicides (e.g. the
strobilurins) are functional at a single
Naturally, when the sprayers
were being bought in the early 1970s,
some growers decided that extremely
high spray pressures (e.g. 300-400 psi)
were necessary to penetrate the peanut
canopy. Certain sales folks helped the
growers cling to such notions. Over
time and with many experiments such
as those done by John Riabov, a for-
mer graduate student in our depart-
ment, we learned that we could back
off the high spray pressures and e-
posit more spray in the canopy rather
than seeding clouds. Thus at that
point, we were already reducing ad-
verse environmental impacts by reduc-
ing the amount of fungicide applied
per acre with the use of the new fungi-
cidal sprays, by minimizing contact of
the loader/applicator with the fungi-
cide, and by minimizing spray drift.
By the mid 1970s, the Envi-
ronmental Protection Agency (EPA)
was at full throttle, and our environ-
mental gains needed follow up. Other
types of studies then began that bene-
fited growers by integrating non-
chemical tactics in the disease control
program. For example, the benefits of
using crop rotation for suppressing
PLS was brought to the forefront
from our field tests for integration into
a disease control program. However,
this tactic is highly dependant upon the
amount of land growers have avail-

By the mid 1970s, an increas-
ing number of growers were attaining
yields in the range of 2 to 2 1/2
tons/acre. Since that time occasional
yields of 3 tons/acre have occurred.
Compare this to the less than 1
ton/acre statewide yields that occurred
commonly prior to the advent of pest
control. I use the term pest control
because another story, not outlined
herein, is the impact of nematode con-
trol on peanut. While disease control
contributed significantly to the rapid
yield increases up through 1978, the
cancellation of DBCP (a highly effec-
tive nematicide), by the EPA, caused
reductions in statewide yields. Actually,
during the 1970s, disease and nema-
tode control, along with utilization of
better agronomic practices and the
availability of an easy to grow cultivar,
Florunner (developed by Drs. Al
Norden, Ralph Lipscomb, and W.A.
Carver in the Agronomy Department
at the University of Florida), all con-
tributed to the "golden years of peanut
production." In 1978, our statewide
average yields were 3310 lb/A. Prior
to 1970, average statewide yields
ranged between 1400 to 1600 lb/A.
In recent years, we have averaged be-
tween 2300 and 2900 lb/A. The con-
temporary reduction in yields com-
pared to the "Golden Years" is a func-
tion of reduced nematode control,
inadequate crop rotations, the use cf
the "additional peanut" marketing op-
tion on increased acres where produc-
tion and pest control puts are mini-
mized, the occurrence of some new
disease situations, and the seemingly
more extreme variations in weather
Before we had even com-
pleted some of the above mentioned
accomplishments during the "Golden
Years", Dr. Dan Gorbet, a recently
hired plant breeder at that time in the
Agronomy Department, initiated a
search in 1972 for resistance to PLS

within the germplasm base of peanut.
He and I both agreed that such a pro-
gram must be initiated even though
certain power brokers in the plant
breeding arena stated that such was not
attainable, and therefore, such would
be a waste of time. Fifteen years later,
the registration of 'Southern Run-
ner'(developed by Drs. Dan Gorbet,
Al Norden, Fred Shokes, and David
Knauft), a cultivar with partial resis-
tance to late leaf spot, southern stem
rot clerotium .-' ;, and rust auccinia
arachidis) was published. This was first
leaf spot-resistant cultivar developed in
the United States. After growers used
the standard cultivar, Florunner, for 18
years, almost exclusively, we thought
the benefits of Southern Runner would
be useful to growers by reducing their
production costs. However, these
benefits were overridden by certain
agronomic characteristics such as re-
duced seedling vigor, smaller seed size,
and late maturation. Late maturation
increases its hazard time for other
problems and conflicts with hunting
seasons. The weak seedling vigor
coupled with its late maturation re-
stricted the planting time to a narrower
window because it did not emerge
well in cooler soils and one can not
plant it too late or it would be ex-
posed to cold weather at the end of
the season. Peanut is a tropical crop.
Southern Runner is still grown by a
few growers to save on costs associ-
ated with spraying or because they
have contracts to grow it for specific
markets. So, if you think that resis-
tance is a panacea to curb disease
problems, keep in mind the reality of
what it nkes to grow a crop success-
fully. Plant diseases are just one com-
ponent within a production scheme.
Such disappointing scenarios have oc-
curred repeatedly with other cultivars
in other crops multiple times all over
the world.


As the search for and devel-
opment of pedigrees with disease ie-
sistance evolved, several graduate stu-
dents in the departments of Plant Pa-
thology and Agronomy conducted
research for their theses and disserta-
tions on the mechanisms of resistance,
epidemiological parameters, or eco-
logical patterns associated with resis-
tance. In Plant Pathology the students
were: Jan Plaut, Greg Watson,
Vermando Aquino, Carlos Forcelini,
and Bob Kemerait. These students
were advised by Drs. Richard Berger,
Fred Shokes and Tom Kucharek. In
Agronomy, Drs. Dan Gorbet, David
Knauft, and Ken Boote advised several
students including Albert Chetika, T.
Monasterios, Kevin Pixley, and Ga-
epan Bourgeois
One of the attributes of
Southern Runner and numerous other
recently released cultivars from univer-
sities and commercial companies is
their partial resistance to tomato spot-
ted wilt virus (1 \\ \), a disease which
was first found in peanut in Florida in
1986. Yield decreases of greater than
50% has been caused by I\\V.
While some in this department stated
repeatedly that I \\ would never be
a problem, the fact is that it is the first
virus to have a negative impact on
peanut production in Florida, and it
has been devastating to peanut
production in Georgia and the entire
industry. The impact of TSWV on
several other crops is a topic for an-
other treatise.
We have learned how to ma-
nipulate plant populations and planting
times to partially suppress 1 \\V in
peanut. Cultivar selection has become
another major tactic for suppression of
1 \\ V. Georgia Green is currently the
predominate cultivar grown in the
southeastern United States because of
its somewhat acceptable agronomic
type and partial resistance to TSWV,
southern stem rot, and rust. How-

ever, Georgia Green has a seedling
vigor problem. Growers and sellers
would prefer a different peanut and
thus, the future of Georgia Green is
likely to be short-lived. Hopefully, the
recently developed cultivar C-99R
from Florida will be adequate. It has
partial resistance to leaf spot, white
mold, TSWV, and rust.
Southern stem rot (white
mold), caused by the soilborne fungus
Sclerotium rofsii, was a constant prob-
lem all through the "Golden Years"
and even before. Its impact on yield
was not always visualized by the grow-
ers until they minimized PLS. With
PLS minimized, they could see the
wilting associated with white mold.
Prior to that, it was generally accepted
by growers that when the "vines went
back", it was time to hook up the dig-
ger to the tractor and begin the har-
vesting process. After they attained
good control of PLS, they wanted to
know how to stop the wilt caused by
S. rofsii. With the many new fancy,
brick farm homes that were being
erected during that era and the new
modern farm equipment that was be-
ing purchased, bills had to be paid.
Growers were not about to have
some white fungus get in their way.
During the 1970s, our only controls
for white mold were crop rotation
and steel in the form of a bottom
plow. For many situations, those tac-
tics were not adequate and our admin-
istrators in IFAS were told by some
Extension Agents that we must have a
control of white mold. In 1975, Dr.
Gary Sandin, a Plant Pathologist lo-
cated at Quincy, Florida, initiated stud-
ies on the chemical control of white
mold. It was not until 1984 in my tests
in Sawannee County and after Gary's
leaving the University of Florida, that a
new fungicide (flutolanil) was devel-
oped by Nor-Am (now Agrevo) and
it provided significantly improved
suppression of white mold. Since

then, Dr. Fred Shokes (formerly at
Quincy) and I tested several efficacious
foliar fungicide sprays that are now
labeled for suppression of white mold.
In tests, we commonly demonstrated
yield increases of one ton or more/A
by suppressing white mold and grow-
ers have attained high levels of control
also. However, the costs of the "new
generation" fungicides are extremely
Another fungal disease of
peanut that must be considered is Cyl-
indrocladium black rot (CBR) caused
by the soilborne fungus Cjyndrocladum
crotalariae (Calonectriaparasiticum). It first
occurred in Florida in 1975. By the
mid to late 1980s, CBR became a se-
vere problem in some fields, particu-
larly in Santa Rosa County. This disease
has reduced yield by as much a one
ton per acre. Beginning in 1989, John
Atkins, an Extension Agent in Santa
Rosa County, and I conducted many
on-farm tests related to control of
CBR. Over the past 12 years, we
have found foliar fungicides that are
partially effective and cultivars with
partial resistance. In recent years we
have manipulated planting dates for

The diseases mentioned above
are the main plant disease problems,
but there are several others. For ex-
ample, yellow mold, caused by Asper-
:- flavs (sometimes A. parasiticus),
can colonize peanuts prior to or after
harvest. If detected at the buying
point, the grower can lose big bucks.
If he normally would get $610/ton
without yellow mold, he would get
less than half of that if yellow mold
was detected. This is a drastic pay cut.
Fortunately, the percentage of peanuts
that are graded Segregation III (with
yellow mold), is typically less than a
percentage point or two statewide.
Maintaining adequate soil moisture and
suppression of pod damage from n-


sects and other causes is helpful in re-
ducing this problem. Jessie LaPrade, a
graduate student with Dr. Jerry Bartz
in the early 1970s, found that some
cultivars are less likely to be infected or
colonized by A. This is a prime
area for future research.
A related fungus, A-.. ii-
ger, has caused serious stand problems
by rotting young plants. Some plant
pathologists are surprised to hear that
A. niger is a true pathogen. Plant pa-
thologists relate to this fungus as a
laboratory contaminant or a pathogen
of the human ear. Maybe this is the
cause of listening impairments in old
professors. We have some rescue treat-
ments for A. niger in peanut, but by the
time the cause is determined, the stands
are drastically reduced and the chance
for TSWV is creased. Because of
some legitimate regulatory actions by
the EPA and priorities established by
commercial companies in response to
some maleficent regulatory actions, we
no longer have adequate seed
treatment fungicides which used to be
adequate for suppressing this fungus.

Pod and peg rots are caused
by several fungi, including Rhizoctonia
spp., S. rofsii, and C. parasiticum. The
complexity of pod and peg rots is well
illustrated by the research of Roberto
Garcia and Bob Kemerait, two PhD
graduate students in Plant Pathology
who were advised by Drs. David
Mitchell and Tom Kucharek, respec-
tively. Some of the tactics that have
been used successfully to reduce peg
and pod rots include crop rotation,
control of nematodes, maintaining high
levels of calcium in the pegging zone,
and the strategic use of certain foliar
Another fungus, Lasiodiploda
theobromae, has been increasingly associ-
ated with dysfunctional peanuts in
Florida. From greenhouse work, we
have learned that this fungus is ex-

tremely virulent, but we do not have
an adequate understanding about the
conditions necessary for this pathogen
to cause damage. Again, we have
some rescue treatments, but their use is
often too late. I am beginning to think
that this fungus will be the target of
several studies in the near future
Probably the biggest problem
we face now, and this problem will
continue to increase in the future, is the
loss of agricultural land. Crop rotation
can be preached to the choir until
Bobby Knight changes his demeanor,
but without adequate land reserves,
crop rotation will become a myth and
a topic for history books. In many
areas of southern Florida, some crops
have had to be planted on the same
land 30 or more consecutive years.
We already have some peanut growers
producing peanuts on the same land
for eight years in a row. Twenty years
ago those same growers would not
have had peanuts on the same land for
more than one year out of every three
to four years. Times are "a changing"
and from my vantage point, we (plant
pathologists) are gradually losing our
position to provide adequate informa-
tion for control of plant diseases
where crop rotation is no longer part
of the integrated crop production sys-

Where in the World Wide

Looking to give something back to
Gainesville or just help out? Here's a
few websites that can help you volun-
teer your time in Gainesville!
* The name pretty much sums up
www.gainesvillepetrescue.org, a site
where you can help Fido and Fifi
find homes. Pet Rescue grants a re-
prieve to adoptable animals from
the county shelter and places them

in foster homes (all expenses paid)
until a suitable home can be found.
Check out the site to become a fos-
ter home or to adopt an animal.
* A volunteer clearinghouse for many
years in Gainesville, The Volunteer
Center (www.volunteer-center.org)
helps place volunteers all over town
in a variety of areas. The site offers
information on their events as well
as a sampling of the volunteer cp-
* Some sites offer volunteer positions
and education- www.ncfan.org, the
North Central Florida Aids Net-
work homepage has a calendar of
events, volunteer contacts and a list
of the HIV/AIDS educational
courses they offer.
* A cornerstone of volunteer efforts
worldwide, the United Way of
( ... i.i -- ; --- I 11 i.h.. .i has a
list of local civic, social and advo-
cacy groups as well as support and
therapy groups you can get involved

Faculty, staff, students,
alumni, and colleagues of our

Graduate students in the c-
partment elected their
officers for 2000-2001.
Marlene Rosales (pic-
tured) will serve as
president for Fall 2000,
Ronald French as
[ vice-president, and
Eduardo Carlos as treasurer. For
Spring 2001, Ronald will serve as
president, Marlene as vice-president,
and Eduardo will remain as Treasurer.
Good luck, officers!!!


At 5 a.m. on
Saturday, August 12,


2000, nine "adventurous" graduate
students hopped into an IFAS van
that would take them to New Orleans,
in order to attend the Annual Ameri-
can Phytopathological Society Meeting.
"Survivors" of this 1000+ mile round-
trip journey were: Aaron Hert, Alba
Nava, Alvaro Urena, Camilla Yandoc,
Denise Tombolato Francisco Ochoa,
Marlene Rosales, Ronald French, and
Yolanda Petersen.

Dr. Carlye A. Baker, Cour-
tesy Assistant Professor in our De-
partment, has recently assumed a posi-
tion as a Plant Pathologist at the Divi-
sion of Plant Industry's Bureau of En-
tomology, Nematology and Plant Ta-
thology in Gainesville. Her specialty is
plant virology and she replaces Dr.
Lawrence G. Brown. Dr. Baker was
\ / born in Klamath Falls,
- Oregon and is married to
Dr. Patrick T. Colahan,
F h who works in the De-
apartment of Veterinary
Medicine. They have one
child, Caila, born in 1994.
Dr. Baker, who received her BS
degree in Child Development at the
University of California at Davis and
her MS degree in Home Economics
from Colorado State University at
Fort Collins, joined our Department in
1986 as a Graduate Assistant. She re-
ceived her Ph.D. degree in 1989 under
the direction of Dr. D. E. Purcifull
(dissertation entitled "Production and
characterization of polyclonal and
monoclonal antibodies to three virus-
induced proteins of papaya ringspot
virus type \\ "). After graduation, she

doctoral position under
Dr. E. Hiebert. Be-
tween 1992 and 1998
Dr. Baker worked with
Dr. F. W. Zettler in
F / developing PLP 2000
("Plants, Plagues, and

People"). She is presently teaching
PLP 2000 as a distance learning class.

Dr. Pete Timmer was named Fellow
of the American Phytopathological
Society (APS) at the 2000 Annual
Meeting held in New Orleans from
August 12 through August 16. Con-

Richard Blacharski, recent depart-
mental graduate, sends his greetings
from his new home in Seattle, Wash-
ington. You can send him a little note
via his e-mail,
rblacharski@excite.com or his home
address : 1705 Belmont Avenue #206
Seattle, WA 98122.

Coffee Breaks and B-

Friday Coffee Break
9-15 Kucharek,
and Song
9-22 Pring and Chourey
9-29 Disease Clinic, Zettler
10-6 Hiebert



Bartz, Berger and

10-20 Charudattan
10-27 Gabriel
11-3 Jones


10-9 Matthew Petersen
10-19 Susan Carlson
10-19 Carlye Baker
10-26 Lisa Tomski
10-28 Jerry Minsavage
10-28 Camilla Yandoc
11-7 James Kimbrough
11-7 Amanda Bishop
11-7 Andy Hutchens


11-8 Stacy Steger
11-8 Robin Oliver
11-9 Rupali Datta
11-11 Ye Li
11-16 Tom Kucharek
11-18 Chuck Semer
11-28 Anita Snyder
11-29 Mark Elliot
11-29 Jan Sapp
11-29 Jim DeValerio

Recent Publications

Legard, D.E., Martin, F.G., Xiao, C.L.,
and Chandler, C.K. 2000. Reduced
sampling frequency for evaluating
fungicide efficacy on Botrytis fruit rot
of strawberry. Plant Disease 84:743-
Murphy, J.F., Zehnder, G.W., Schus-
ter, D.J., Sikora, E.J., Polston, J.E., and
Kloepper, J.W. 2000. Plant growth-
promoting rhizobacterial mediated
protection in tomato against Tomato mot-
tle irus. Plant Disease 84:779-784.

Seebold, K.W., Datnoff, L.E., Correa-
Victoria, F. J., Kucharek, T.A. and
Snyder, G.H. 2000. Effect of silicon
rate and host resistance on blast, scald,
and yield of upland rice. Plant Disease

Timmer, L.W., Darhower, H.M.,
Zitko, S.E., Peever, T.L., Ibanez, A.M.,
Bushong, P.M. 2000. Environmental
factors affecting the severity of Alter-
naria brown spot of citrus and their
potential use in timing fungicide appli-
cations. Plant Disease 84: 638-643.

CVC and the Xylella fas-
tidiosa Genome Project

Tc....i .1. -. has transformed our
world in several ways and genome
projects are among the most notewor-
thy. The first plant pathogen genome

to be sequenced is that of XJ -L fas
tidosa, the causal agent of Citrus Varie-
gated Chlorosis, CVC. One might
wonder "\\ I would the Brazilians
spend US$ 13.5 million to sequence X.
The presence of CVC has been
traced to the mid-80's in northwestern
Sio Paulo State, Brazil. At that time
several sweet orange ( sinensis L.
Osbeck) groves started to show symp-
toms similar to the habitual foliar zinc
deficiency, but with the not so com-
mon brown little spots underneath the
leaves. They varied in size ranging
from small spots to larger ones re-
sembling leaf scorch in some cases.
Symptoms on the tree may have been
overlooked by growers if fruit mar-
ketability hadn't been decreased by the
much smaller, harder and bitter fruits.
Growers were concerned since fruits
were being left on the trees or thrown
away after harvesting.
Research institutes were called
on to solve this problem and the first
"hypothesis" was that there was some
relationship with nutritional deficiency.
Between 1993 and 1994, the contribu-
tion of several researchers and farmers
were critical in proving that X j fas
tidosa was in fact the real causal agent.
In 1996, xylem-feeding sharpshooter
leafhoppers were confirmed as vec-
tors, the final piece of the puzzle. To
the growers, the real question for the
scientific community was "How can
we control the disease?" The only an-
swers so far are starting with disease-
free buds or growing a citrus crop
other than sweet oranges, that are un-
affected by CVC.
Indeed, many growers in
Brazil were forced to switch to other
business enterprises because of CVC.
Attempts made to control the insect
vectors with hsecticides and to prune
affected branches, did not provide
sufficient control in the long run. In
spite of the ongoing huge Brazilian

sweet orange production, CVC had
managed to spread out thus increasing
the importance of X. fastidosa. Finally,
authorities came to the natural conclu-
sion that "Hey, we have a problem!"
Such statement catapulted this xylem-
limited gram-negative bacterium to a
potential candidate for any extensive
But, a stronger reason for a
wide project would be the opportunity
to train and educate people in science-
specially if it was in a "hot" field of
science- probably motivated many into
becoming project mentors and leaders.
This way of thought complemented
the high demand for better education
at all levels in Brazil and with a con-
stant pledge of the local scientific
community to try to help society. The
result was a strong support for a pro-
ject that would involve different fields
of study from different institutions that
would use their current expertise in
areas such as biochemistry, molecular
biology and informatics. Thus, the path
was paved for a genome project. Fur-
ther, a fancy network system was cre-
ated to do the job, and was called
ONSA (Organization for Nucleotide
Sequencing and Analysis), which in
Portuguese sounds exactly like 'Onga',
the name of a jaguar-like big cat nor-
mally found in the Amazon forests.
The strong research drive and
ultimately, the availability of funds
th were fundamental in
launching the genome
project. (The Brazilian
economy had substan-
tially improved in comparison to ear-
lier years and thus the real constraint
had more to do with the challenge of
doing something new than the lack of
resources. "\\ can do it! Why not?"
braved some authorities.
The above events made it
possible for Xj L fastidosa to be cho-
sen as the organism of choice for such
a project. The project was ultimately

thought-out, created, and coordinated
by FAPESP, a Sio Paulo State spon-
sorship agency, after deliberations with
other institutions such as: Ludwig Insti-
UNESP, Instituto Biol6gico, INRA,
Fundecitrus and several others that
helped to solidify the project. This ef-
fort was allocated US$13,000,000
from FAPESP, and US$500,000 from
Fundecitrus, an organization main-
tained by growers and juice processors
devoted to protect the citrus industry.
This fund was shared among 34 e-
search labs on work-basis, with around
195 total people involved from several
Sio Paulo State institutions. The discus-
sions and formulation of procedures
started on November 1997 and culmi-
nated with a publication in Nature on
July 13th, 2000. During the project,
labs were nicely equipped, scientists
were trained, and, interesting enough,
results were obtained.
The paper in Nature reported
2,679,305 base pairs (bp) in the main
chromosome of the bacterium and
51,158 bp and 1,285 bp in two plas-
mids. No surprises were found in the
basic functions of the genome content
and the replication, translation and re-
pair mechanisms were all there. En-
ergy metabolism was thought to be
based on carbohydrates and that
would be expected since X. fastidiosa
acquired strategies to survive in a poor
environment, the xylem space, which
has less nutrients but also less competi-
tors. Small molecule metabolism
pathways were present as well as puta-
tive transport-related proteins. Extra-
cellular polysaccharides were thought
to be synthesized by enzymes encoded
by its gnome and it seemed reason-
able because X. fastidosa apparently
lives in clamps in the xylem vessels.
Toxicity factors to the host
were also thought to be found, and
they may play an important role in the
disease symptom development be-


cause another constraint, Citrus Blight,
has only xylem vessel obstructions and
nevertheless has no similar symptom
pattern to CVC. Pectolytic enzymes
probably mediated migration of X.
fastidosa between xylem vessels and this
potential mechanism may be important
for host colonization. Bacteriophage
sequences were found in the X. fas-
tidosa genome and potentially ac-
counted for variability and evolution
of the bacterium. Whether this fact
might account for differences in CVC
severity between Northern and South-
ern Sio Paulo State remains to be clari-
fled. Finally in the port, there is an
apparent inexistence of Vir genes since
X. fastidiosa is found in many plant
species and does not require host cellu-
lar infection. Maybe another mecha-
nism is involved to attack a specific
host. Obviously, many questions need
to be answered and which, hopefully,
the follow-up Functional Project can
do in the near future.
The enthusiasm and commit-
ment to the project was outstanding.
People from different backgrounds
only wanted to help and they brilliantly
did. Major results: lots of learning for
sure! Besides dwelling into molecular
biology and bio-informatics, iesearch-
ers even learned to distinguish oranges
from tangerines. Growers' questions
may still remain unanswered but the
quality of the information obtained
opened the doors for other projects
such as Xanthomonas, Sugar Cane
EST, Human cancer, and other ge-
nomes. The incredible support of soci-
ety, the citrus industry and scientific
community made the Xj fastidosa
Genome Project a success story that
surely marveled many faculty, staff and
Eduardo F. Carlos

What Happened???

What a difference 50 years can make! The
following is from an actual 1950's
Home Economics textbook intended for
High School girls, teaching them how to
prepare for married life.

ahead, even the night before, to have a deli-
cious meal on time. This is a way of letting
him know that you have been
thinking about him, and are co ncemed
about his needs. Most men are hungry
when they come home and the prospects of
a good meal are part of the warm welcome

minutes to rest so you will be refreshed
when he arrives. Touch up your make-up,
put a ribbon in your hair and be
fresh looking. He has just been with a lot of
work-weary people. Be a little gay and a little
more interesting. His boring day may need a

one last trip through the main part of the
house just before your husband arnves,
gathering up schoolbooks, toys, paper, etc.
Then run a dust cloth over the
tables. Your husband will feel he has
reached a haven of rest and order, and it will
give you a lift too.

a few minutes to wash the children's hands
and faces if they are small, comb their hair,
and if necessary, change their clothes. They
are little treasures and he would like to
see them playing the part.

time of his arrival, eliminate all noise of
washer, dryer, or vacuum. Try to encourage
the children to be quiet. Greet him with a
warm smile and kiss, letting him know
you're glad to see him.

6. SOME DON'TS: Don't greet him
with problems or complaints. Don't co m-
plain if he's late for dinner.
Count this as minor compared with what
he might have gone through that day.

Have him lean back in a comfortable chair or
suggest he lay down in the bedroom. Have
a cool or warm drink ready for him. Arrange
his pillow and offer to take off his

shoes. Speak in a low, soft, soothing and
pleasant voice. Allow him to relax and un-

8. LISTEN TO HIM: You may have a
dozen things to tell him, but the moment
of his arrival is not the time. Let him talk

complain if he does not take you out to
dinner or to other places of entertainment;
instead try to understand his world of strain
and pressure and his need to be home and

10. THE GOAL: try to make your home
a place of peace and order where your hus-
band can relax.


reservations ahead of time. If your day be-
comes too hectic just leave him a voice mail
message regarding where you'd like to eat
and at what time. This lets him know that
your day has been bad and gives him an
opportunity to change your mood.

to change out of your work clothes into
something comfortable. Who cares if he
likes it or not... after all, it's most likely his
T-shirt and boxers.

right! Tell the kids and your husband if
they want maid service, they better call one!

the children to their rooms to watch televi-
sion or play Nintendo.

him over the loud music your kids are play-
ing, that this is what you had to put up
with while he was gone. And mention that
it was his decision to buy the kids a new CD
player in the first place.

6. SOME DON'TS: Don't greet him
with problems and complaints. Let him
speak first, and then your complaints will
get more attention and remain fresh in his
mind throughout dinner. Don't complain
if he's late for dinner, simply
remind him that the leftovers are in the
fridge and you left the dishes for him to do.


him where he can find a blanket if he's cold.
This will really show you care.

8. LISTEN TO HIM: But don't ever let
him get the last word.

complain if he does not take you out to
dinner or other places of entertainment; go
with a friend or go shopping (use his credit
card). Familiarize him with the phrase
"Girls' Night Out!"

10. THE GOAL: Try to keep things amica-
ble without reminding him that he only
thinks the world revolves around him. Ob-
viously he's wrong, it revolves around you.

An Event Not To Be

Many people pass through Gainesville
without ever noticing one of the
town's best features- transience. And
why is this such a
beautiful thing? Moving
students don't want
to move their books
so they donate them.
And where does the
overflow of books from the student
exodus go? The Friends of the Library
Book Sale! Each time I introduce peo-
ple to his sale, the disbelief on their
faces that people actually sleep in the
parking lot overnite to get the front
space in line is worth arriving 2 hours
early to avoid the worst of the rush.
Held each fall and spring in a ware-
house (that's right, a warehouse of
books), the sale charges between ten
cents and a few dollars for books in
every category imaginable. If you're
looking to build up your personal 1-
brary or looking for textbooks for
next semester for dirt cheap, this is the
place to look. This year's sle will be
Oct. 21-25, starting at 9am on the 21st.
Get there early- the line winds several
blocks down the street by the time the

doors open. I'll be waiting in line, see
you there!

Who's Who New
Graduate Students

Fabricio Avila Rodrigues is
a new PhD student from Aragriari,
Brazil. His main advisor is Dr. Law-
rence Datnoff, from the Everglades
Research and Education Center
(EREC) in Belle Glade. Fabricio ob-
tained his B.S. at Uberlandia Federal
University in Agronomy in 1996. This
past spring he received his M.S. degree
from Vicoza Federal University in
Plant Pathology. He studied the effects
of silicon on rice sheath blight control.
Fabricio spent the past sum-
mer at the EREC writing up the jour-
nal articles on his recent research,
which will be submitted in both Eng-
lish and Portuguese. His PhD project
will be studying the mechanisms of
resistance by Si in the control of blast
(3.A-,l'.,,,^''' grisea) on rice. Here in
Gainesville, his co-advisers are Dr.
Jones and Dr. Kucharek, and Fabricio
will be working in Dr. Jones lab. Also
advising Fabricio is Dr. Gaspar Korn-
dorfer, a professor in Brazil and a
strong advocate of silicon in agricul-
Fabricio enjoys playing soccer,
swimming, movies, travel, and reading.
He was my roommate at the EREC
this past summer, is a good friend, and
will no doubt be a great addition to
our PLP family.

Another new grad student
this semester is Botond "Bo" Balogh
from Ulles Hungary. His undergradu-
ate career is interesting in that it consists
of many parts. Bo first spent four
years studying h Hungary at Godoll6i
AgrArtudomAnyi Egyetem (Godolli
Agricultural University). While attend-
ing the university he spent 3 months
studying abroad at the famed Pushkin

Russian Language Institute in Moscow,
learning Russian. It was there that in
the midst of speaking Russian and
drinking vodka, he met his wife
Justyna. He then came to the US as a
trainee of the Communicating for Ag-
riculture Exchange Program (CAEP)
and worked in Amesbury, Massachu-
setts. He then continued working for
the CAEP at their sister facility in
Rockledge, Florida and did 2 semes-
ters at Brevard Community College.
Finally Bo came to UF for 2 more
semesters and graduated with a major
in plant science.
Bo was employed as work study
his last year of undergrad in Dr. Jeff
Jones lab. Bo was just offered a full
assistantship in August by Dr. Jones to
obtain his Masters degree. His thesis
project will be developing and testing
different formulations to enhance the
longevity of a bacteriophages life once
sprayed on the tomato plant. These
bacteriophages will be used as a bio-
logical control of Xanthomonas
campestris vesicatoria (I 1.r il! spot).
Bo shared with me an interesting
anecdote of his marriage. He actually
got married twice; first officially at the
marriage office in Hungary with his
folks, then to Poland where she was
from for a more traditional church
ceremony with her family. The cere-
mony was held at the catholic church
of the Polish army and at he same time
outside in the park of the church there
was a Catholic heavy metal rock and
roll concert. Even with the doors and
windows to the church closed, the
couple could barely hear each other's
vows. And to top it all off his wife
lost her ring one hour before the
ceremony in a meadow where they
had their pictures taken. His wife used
Bo's mothers' ring to take its place and
to this day they have never found it.
Bo enjoys reading humorous novels and
his favorite writer is P. Howard. He prac-
tices his language skills with his wife, who
teaches Russian and Polish at Santa Fe


Community College. Bo hopes to go on to
a PhD in plant p ii,..1 ._ -. and will see what
the future holds from there. (Matt Brecht)

Biotech Briefs

By Anita Snyder

In today's world there is so much
information available that it is impossi-
ble to keep up with everything. The
disciplines within science are abstruse
not only to the general public but also
for scientists who concentrate in dispa-
rate fields.
Within the Department of Plant
Pathology, a gap may form between
folks who study classical plant pathol-
ogy and those that concentrate on mo-
lecular plant -. lih..1.._ With this
much diversity, it is important to have
a common ground to begin a discus-
The aim of this column is to dis-
cuss molecular techniques and to give
readers an overview of how a molecu-
lar tool works, what it can tell you, and
how it may be used for purposes
other than basic science. My hope is to
be able to encourage discussion about
molecular concepts and to discuss mo-
lecular techniques that are being used
for applications such as disease diagno-
If anyone has a topic they would
like to see within this column, please
e-mail the PLP News.

Perhaps the most fundamental
concept in molecular biology is Francis
Crick's "Central Dogma". Crick first
published this hypothesis in 1958. At
this time, scientists were working to
define how biological organisms store
information, inherit traits, and direct
biological processes. Crick's Central
Dogma became a fundamental con-
cept that directed research in the bur-
geoning field of molecular biology.

Crick believed that the nucleic ac-
ids were the inherited material and the
source of the information in proteins.
He proposed that the biological in-
formation is stored in the form of
DNA and directs the organism
through its action as a protein. The
Central Dogma proposed that bio-
logical information flows in one direc-
DNA -> RNA -> Protein
Protein is the end point for this in-
formation. Proteins can be enzymes,
regulatory factors, or structural com-
ponents, but not stores of biological
Early "molecular biologists"


worked to understand
the components of the
Central Dogma. Re-
searchers began to focus
on DNA in order to
determine all protein se-
This led to the study of the

transcription and translation machiner-
ies and to the current work of se-
quencing the genomes of several cr-
The discoveries of systems that do
not linearly transfer information from
DNA -> RNA -> Protein challenge
the Central Dogma. These discoveries
include reverse transcription, mRNA
splicing, mRNA editing, epigenetic
inheritance and prions.
RNA viruses have shown us that
RNA can be the hereditary material
and can be reverse transcribed into
DNA. This exception is easily incor-
porated into the Central Dogma, as a
flow of information between nucleic
Therefore, the concise version
DNA -> RNA -> Protein is oversim-
plified. The Central Dogma includes
the following information pathways:
DNA can replicate to form DNA,
DNA can transcribe to form RNA,
RNA can duplicate, RNA can reverse
transcribe to DNA, and RNA can

translate to create protein. Currently,
the Central Dogma predicts against
information transfer from protein to
protein and from protein to nucleic
In eukaryotes, splicing and mRNA
editing alter the sequence of the
mRNA so that it no longer directly
matches the DNA. mRNA editing can
be extensive within certain genes; one
noteworthy mRNA contains nearly
650 edited bases. The resulting mature
proteins are not actually encoded
within the genome, demonstrating that
these mechanisms interfere with the
ability to predict protein sequence di-
rectly from DNA sequence.
Epigenetic information, in the
form of modifications t DNA such
as methylation patterns, can alter the
transcription of regions of DNA.
These modifications can arise within
the parent and be transmitted to the
progeny, yet are not specified by DNA
An additional challenge originates
at the protein level in the form of pri-
ons. Prions are infectious agents that


seem to consist only of protein, yet are
able to multiple in the host. Does this
mean that information from protein
can go to protein or nucleic acid, or is
the nucleic acid of prions so far unde-
Some of these exceptions at
the nucleic acid level have incorporated
into the Central Dogma to form a
model that has directed research and
teaching for over 40 years. Will the
Central Dogma tolerate exceptions
such as mRNA splicing, mRNA edit-
ing, epigenetic inheritance, and prions?
This Central Dogma has proven to be
complex and flexible as additional dis-
coveries expand the scope of molecu-
lar biology.

Thieffry, D. and Sarkar, S. 1998.
TIBs, 23: 312-316.
Hunter, N. 1999. Trends in Micro-
biology, 7: 265-266.

Anita Snyder is a M.S. student in the Plant
Molecular c& Cellular Biology Program and works
with Dr. Wen-Yuan Song in the Department of
PlantP .Gainesville.

The PLP Newsletter would like to
thank Angela Vincent for devoting
2+ years to our publication. We
appreciate your effort, staples and
dedication. Good luck!

If you would like to join our staff or con-
tribute an article, contact us!

PLP News
1453 Fifield Hall
P.O. Box 110680
Gainesville, FL 32611-0680

Or, you can e-mail

us at:

News Team Sept-Oct 2000
Ronald French (Ed.)
Misty Nielsen (Ed)
Matt Brecht
F.W. "Bill" Zettler
Camilla Yandoc
Eduardo Carlos
Anita Snyder

The opinions expressed in this newsletter are not
necessarily those of the PLPNews '

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