view article - American Phytopathological Society

deposition or unfavorable conditions for spore germination and photosynthetic rates and lower stomatal conductances at ambient
infection. Low severity in limed plots may result fran reduc- C0 2 (340 ppm), and significantly reduced levels of active
tion of primary inoculumn from leaf litter or nutrient-related RUBISCO. Protein extrayion and subsequent total activation of
differences in susceptibility. Results suggest little disease extracted RUBISCO with `C indicated a significant reduction
impact on regeneration after seedlings achieve heights >30 cm. in the total amount of RUBISCO in infected leaves.
70 74
ALLOZYME DIFFERENTIATION AMONG INTERSTERILITY GROUPS OF
HETEROBASIDION ANNOSUM ISOLATES FROM EUROPE. W.J. Otrosina,
T.E. Chase, F.W. Cobb, Jr. and K. Korhonen. USDA Forest
Service, Pacific Southwest Forest and Range Experiment Station,
P.O. Box 245, Berkeley, CA 94701; Department of Plant
Pathology, University of California,
Institute,
Berkeley; Finnish
Helsinki,
Forestry
Finland.
EFFECTS OF PLANT GROWTH REGULATORS ON ACREMONIUM COENOPHIAWUM
GROWTH IN CULTURE. G. E. Huff, K. D. Gwinn, and C. E. Sams.
Departments of Entomology and Plant Pathology and Plant and Soil
Science, University of Tennessee, P.O. Box 1071, Knoxville TN
37901.
Growth of the fungal endophyte (Acremonium coenophialum Morgan-
Starch gel electrophoresis was conducted for isolates from
Finland, Germany, and Italy representing "P', "S", and "F"
intersterility groups. No clear differences in mobilities were
found between the "S" and "F" groups in any of the 12 loci
analyzed. In general, mobilities for the MDH-2 locus for all
European isolates were indentical to the North American "S"
group. The ADH, IDH, and GDH locus showed consistent
differences between the "P" and "S" or "F" groups. Other loci
exhibit shared alleles among the intersterility groups, which
is in contrast to the nearly total fixation present in most
loci betweeen the "S" and "P" groups in western North America.
Within the "S" and "P" groups, allele frequency differences are
apparent between isolates from both continents.
Jones and Gams) is stimulated
fescue
during
(Festuca
the transition
arundinacea
of
Schreb.)
tall
from the vegetative to
reproductive state. This study was initiated to determine if
plant growth regulators elicit a growth response by the
endophyte. Plant growth regulators, dicamba and gibberellic
acid, had no significant effect on the growth rate of the
endophyte in culture. Kinetin completely inhibited growth of
the endophyte at a concentration of 100 4M, and reduced
endophyte growth by 75-80% at 80 pTM. Other plant growth
regulators are currently being examined to determine in vitro
effects on endophyte growth.
75
A cultivar-specific elicitor of the hypersensitive response in soybean has been identified
which is associated with expression of the avirulence gene, avrD. Mark 71 M. Stayton*,
Stanley J. Tamaki**, and Noel Keen§ *Department of Molecular Biology, University
SEEDLING Wyoming,
of
RESPONSE OF TWO FOREST TREE SPECIES TO Field
Laramie,
Station,
WY
Richmond,
82071; "*Cleargene,
CA 94804-4698;
Inc.,
§Department
University of
of
California-Richmond
VARYING DOSES OF OZONE
Plant
USING
Pathology,
OPEN-TOP
University of
CHAMBERS IN California at Riverside, Riverside, CA
NORTHCENTRAL
92521-0122.
Davis, Dept. of Plant PENNSYLVANIA. Pathology, The M. Pennsylvania Simini, J.M. State Skelly, University, and D. D. A bacterially produced, low molecular weight compoand, has been idenitified which is a
University Park, PA 16802
cultivar SE compound specific
is elicitor
associated (SE) of
with
the hypersensitive
the
response
expression
in soybean. The
of
presence
the
of the
avirulence
Open-top chambers were
gene,
established
avrD,
at three sites in northern
originally
PA. Four 2- cloned
year-old
from Pseudomoassyringe
seedlings each of Prunus
pv. tomato
serotina
(Kobayashi
Ehrh. and
et.
Liriodendron
al. PNAS 86:157,
tulipifera
1989).
L. were
Expression
planted
of the
in 1987
avD
in
gene
each
in Ps.
of 16
pv. glycinea
plots in a
R4
randomized
alters the interaction
complete
of
block
the bacteria
with
design
the cultivars
at each
IHarosoy'
site. In
and Norchief
1988, the
from
seedlings
compatible
were
to
exposed
incompatible.
to ambient
The presence
air (no
of
chambers)
the avirulence
or to air
gene,
in filtered
however,
chambers
does not
which
alter the
contained
compatible
94%,
interaction
59% or 42%
with the cultivar
'Acme'. Furthermore,
of
E.
the
coli
ozone
cells overexpressing
(03) in ambient
the
air.
ayrD
The
gene
number
elicit the
of hours
hypersensitive
which 03 exceeded 60 response
ppb at the
on exactly
three
the
sites
same
was
set of cultivars
600, 646,
as does
and
Ps.
451
pv. glycinea
hrs, respectively.
R4-avrD. The SE
Ozone- compound
induced
can be
stippling
isolated from
occurred
cell-free
on
culture
the adaxial
supernatants
leaf surface
of E. coli,
of
P.s.
both
pv. tomaa
species
and
at all !!.s. pv. glycinea
sites. Differential
R4 which express
sensitivity
the avrD
was
gene.
found
In
among
partially
treatments
purified extracts,
and sites.
the
Injury
SE
was correlated compound causes a systemic
growth
positively necrosis
were
with only
correlated
ozone dose. in cultivars
negatively
Total height and basal diameter strains expressing the avrD gene. We have
which
purified,
are
by
incompatible
with 03 dose. reverse-phase
with
HPLC,
bacterial
active SE and have initiated an analysis of its chemical
a biologically
structure.
72
DISTRIBUTION AND INSECTICIDAL ACTIVITY OF ALKALOIDS IN FUNGAL
ENDOPHYTE-INFECTED GRASSES. , L.P Bush, N. Fannin, G.C.M. Latch,
D.D. Rowan, and B.A. Tapper. Plant Pathology, University of Kentucky, Lexington, Ky.
40546; DSIR Palmerston North, New Zealand.
A model for the gene-for-gene interaction between P.syringae and soybean.
Tamaki*,
Staley.,L
Mark M. Stayton**
California-Richmond
and Donald Kobayashi§
Field
*Cleargene,
Station,
Inc.,
Richmond,
University
CA
of
94804-4698; "*Department of
Molecular Biology, University of Wyoming, Laramie, WY 82071; §Department of Plant
Pathology, University of California at Riverside, Riverside, CA 92521-0122.
The distribution of N-formyl and N-acetyl lolines, peramine, lolitrem and ergovaline was
determined in Acremonium spp.-and Epichloe typ/i'na-infected cultivars and species
Lolium
of
and
Festuca,
other grass genera. thirty of 34 host-fungus combinations produced alkaloids,
peramine and ergovaline were the most common found alkaloids, while lolines and lolitrem
were the least common. Three alkaloids (lolines, peramine, and ergovaline)
A. coenophialum-infected
were recovered from
tall fescue and perennial ryegrass, while peramine, lolitrem, and
ergovaline infected F. were longifolia. present
Other
in A.
host-fungus
lolii infected perennial
combinations
ryegrass, tall fescue, and in
produces
E. typhina
only one or two of these
alkaloid types. Aphid bioassays, using infected grsss stems, indicated that loline alkaloids were
toxic to Rhiopalosiphusm padi (Rp) and Schu'zaphiis graminum (Sg); peramine was toxic only to
Sg and ergovaline was not toxic to either aphid. Lolitrem was not toxic to Rp, but it could not
be determined if the alkaloid was toxic to Sg as peraimine was always present in the same
infected grasses. The relationship of alkaloid synthesis in infected grasses and resistance to
In gene-for-gene systems the interaction between a dominant
corresponding
resistance
avirulence
gene in
gene
the host
in the
and
pathogen results in an incompatible interaction
characterized by the hypersensitive response (HR). We have isolated a low molecular
cultivar-specific
weight
elici'or (SE) from a phytopathogenic bacterium; suggesting that the
primary gene product of the avirulence gene is not directly involved in the recognitional
event. Rather, the avirulence protein is predicted to possess a catalytic
the synthesis
activity involved
of the
in
specific elicitor. The
receptor,
current
the resistance
models
gene product,
hypothesize
which interacts directly with
the
the
presence
specific elicitor
of a host
triggers the
and
cascade of events manifested as an HR. Alternatively, the target within the plant
for the specific elicitor may not be a dedicated receptor but may play other roles in plant
metabolism. The biological effect of the SE shows parallels those of host-specific toxins
produced by various IIelm~ialisnthsoriuim spp. and Alsnr spp. We will discuss the
similarities in biological activity between the specific elicitor and various host-specific
toxins and propose a working hypothesis which may account for both types of specificity.
herbivory will be diacussed.
73 OXALIC ACID, K 2 HP0 4 AND K 3 PO 4 AS INDUCERS OF SYSTEMIC
RESISTANCE AGAINST DISEASES CAUSED BY FUNGI, BACTERIA, AND
F-OIDSYNTmESIS AND STOM4ATAL RESPONSE IN A SUSCEPTIBLE ALFALFA VIRUSES IN CUCUMBER. Mucharromah and J. Kuc, Dept. of Plant
CLONE INFETE WITH VERFTICILI.JtI4 ALBO-ATRUM. B.W. Pennvpacker, Pathology, University of Kentucky, Lexington, Kentucky 40546
D.P. Knievel, K.T. Leath and E.J. Pell, Penn State Univ. and
USDA~-ARS, U.S. Regional Pasture Jab, Univ. Park, Pa. 16B02. Oxalic acid, K 2 HPO 4 and K 3 PO4, induce systemic resistance to
Phiotosynthesis was measured on a susceptible cucumber
alfalfa
anthracnose
clone caused by Colletotrichum
effectively as
lagenarium
induction with
as
infected with V_. albo-atrums
_C.
and
lagen_,
compared
arium.
to
Spraying
that of control
with
either oxalic acid, K2 HPO4 or
plants.
K3 PO4 on
Infected
the abaxial
plants surface
had symptoms of Verticillium wilt, but of leafI also induced
photosynthesis
systemic resistance
was determined
against
only on asymptcomatic leaves. The Cladosporium cucumerinum,
leaf being measured
tobacco necrosis
was placed
virus,
in a sampling ch1amber and Sphaerotheca fuliginea,
exposed Pseudomonas to ca. 750 lachrvmans,
ppm CO2. Sequential measurements were Mycosphaerella
taken
melonis,
at 15 sec.
cucumber
intervals mosaic
for
virus
20 min. and Erwinia
as 032 was depleted by tracheiphila.
photosynthesis. This evidence
A/Ci supports
response the
curve hypothesis
analysis that
was used, which plants have the potential
allowed for
in vivo
resistance
assessment to many
of the
pathogens,
amount of active RUBISCO in and that defense mechanisms can be induced by stress as well
the leaf. Leaves on infected plants had significantly lower as by infection.
1144 PHYTOPATHOLOGY
76