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increased from 0% (Bolinha) and 60% (Corona) after 2 hr of wetness to resistance against two compatible isolates. NIs CL03TTP,
12.5-25% (Bolinha) and 100% (Corona) after8 hr of wetness. Histological C104LAC, C1O1PKT, and C105TTP-4 showed 29-61% fewer lesions than
studies of fruit, in similar stages of development, demonstrated C039. NIs C104PKT and C102PKT differed little from C039. Thus,
morphological differences in the epidermal tissue between resistant certain NIs have residual resistance compared to the recurrent
(Bolinha, Kakamas) and S-genotypes (Corona, UCL)18-8-11). Generally, parent. Efforts are underway to pyramid resistance genes from
R-genotypes had a thicker cuticle, compact epidermal cells, and fewer the NIs showing residual resistance.
trichomes that originated from the first cell layer of the epidermis.
388 392
EVIDENCE FOR CYTOPLASMIC OR MATERNAL DETERMINANTS IN THE
VARIATION IN TOLERANCE TO BENOMYL AMONG COLLETOTRICHUM REACTION OF WHEAT CULTIVARS TO TAN SPOT. Shabeer, A., W. W.
GLOEOSPORIOIDES ISOLATES FROM MANGO. R.T. McMillan, Jr., Bockus, and B. L. Norman, Dept. of Plant Pathology, Kansas State
Michael M. Moss, L.R. Bowling,and L. Stempel, University of Univ., Manhattan, KS 66506.
Florida, IFAS, Trop. Res. & Educ. Center, Homestead, Florida
USA, 33031.
Two tan spot-resistant winter wheat cultivars, Red
and
Chief
Auburn
(RCH)
(ABRN), were crossed with susceptible TAMI05.
In 1987 and 1988 a mango grove located in Dade County Florida Parent and F1 seed of reciprocal crosses was produced in the
USA lost over 50% of the crop to mango anthracnose caused by C.
g1oeosporioides.
greenhouse.
The
Plants
grove
were
was
grown
sprayed
in a randomized
with 1 1/2
block
ibs of
design with
oeosporo ideskly Te gover asd sperayedto4
grehue-lnswr-rw
withk1 1/2er lbsfr
i admzdbokdsg
set 9 replications, 10 plants/entry/replication,
benomyl
inoculated
weekly in flower
with a
and every 3 to 4 weeks after fruit set conidial suspension (1 3 ,000/ml) of Drechslera tritici-repentis,
by the owner in 1987 and by a professional grove management and placed in a mist chamber. The top
company
3 leaves
in 1988,
of each
with
plant
no noticeable control of anthracnose in were rated on a 0-5 scale. Average leaf ratings using
both
ABRN
years.
as
In the summer of 1988, 100 infected fruits were the resistant parent were: ABRN - 0.79,
harvested
ABRN X
randomly
TAM105 (F 1 ) =
from the grove from which 84 single spore 1.80, TAM105 X ABRN (F1 ) 2.18, and TAM105 -
colonies
2.50. Av
were isolated. The isolates were screened at 0, 1, 10, ratings using RCH were: RCH - 0.91, RCH X TAM105 (F 1 ) =
and 100 ppm
2.10,
of benomyl. Out of 84 single spore colonies, nearly TAM105 X RCH (F 1 ) = 2.35, and TAM105 = 2.75.
40%
Ratings
were tolerant
of F
to 10-100 ppm of benomyl, while 1
60% were plants when the resistant parent was used
sensitive,
as a female
showing little or no radial growth. These results significantly (E = 0.05) less than when it was used as ale
may explain the lack of anthracnose control by benomyl in the indicating reciprocal effects.
grove.
389 393
INFECTION OF PEPPER MESOPHYLL PROTOPLASTS WITH PEPPER MILD INDEPENDENT SELECTION OF RESISTANCE TO USTILAGO SCITAMINEA AND
MOTTLE VIRUS USING ELECTROPORATION. J.L. Jacobs and C.T. SUGARCANE MOSAIC VIRUS (SCMV) IN SUGARCANE. M. P. Grisham, B.
Stephens. Michigan State University, East Lansing, MI 48824. L. Legendre, and J. W. Dunckelman, USDA, ARS, Sugarcane Research
Unit, Houma, Louisiana 70361.
Mesophyll protoplasts of pepper (Capsicum annuum) were inoculated
with pepper mild mottle virus (PMMV) by electroporation. Sugarcane
The protoplasts,
smut caused
derived
by Ustilago
from
scitaminea
cotyledons
and
of
sugarcane
seedlings grown mosaic (SCM) caused by SCMV are important
in
diseases
vitro, were
of Louisiana
obtained by treatment with an enzyme solution sugarcane. One-hundred
containing
sugarcane
1.0%
clones
(w/v)
from
Cellulysin,
each of four
0.5% (w/v) Driselase, 0.1% biparental crosses of parents
(w/v) Macerase,
with different
CPW
combinations
salts and 0.4
of
M sorbitol at pH 6.0. reactions
Infection
to U. scitaminea
was
and
achieved
SCMV
with
were evaluated
several direct
for
current pulses resistance t6the two pathogens
of 10
in
msec
separate
at a
field
field
tests.
strength
No
of 0.36 to 0.57 kV/cm and association was found between
a virus concentration
resistance or susceptibility
of 100 pg/ml in
to U.
a 0.7 M mannitol solu- scitaminea and to SCMV
tion.
within
The
or
proportion
among the progeny
of infected
of the
protoplasts
four
was quantified crosses. The
by
breeder
staining
can
with
therefore
viral coat
concurrently
protein-specific
select for
antibodies conju- resistance to U. scitaminea and SCMV, or
gated
independently
to fluorescein
select
isothiocyanate. The percentage of viable for resistance
protoplasts
to one without
after
increasing
electroporation
the probability
was determined
of
by Evan's selecting for
blue
susceptibility
exclusion.
to
Variables
the other.
that
Among
influence
the four
the optimum uptake crosses, the number of clones
of
that
whole
developed
virus
smut
particles
was greater
(PMMV)
in
into protoplasts of pepper one cross in which the female
are
parent
being investigated.
was susceptible to U.
scitaminea, but the number of clones with SCM did not diTf'er.
390 394
HERITABILITY OF RESISTANCE TO WINTER STRESS FACTORS IN DACTYLIS The Effect of Ethylene and Silver Thiosulfate on the Disease
GLOMERATA. Anne Marte Tronsmo, Norwegian Plant Protection Expression of Colletotrichum lagenarium on Cucumber Leaves.
Institute, P.O.Box 70, N-1432 AS-NLH, Norway. C. Biles, F. Abeles, and C. Wilson. USDA-ARS, Appalachian Fruit
Research Station, 45 Wiltshire Road, Kearneysville, WV.
In Norwegian climate winter survival is a critical stage in the
cultivation of perennial grasses. Winter injury is caused by CUcumber seedlings were sprayed with 1mM silver thiosulfate
snow molds and several abiotic factors. Improved winterhardiness (STS) or gassed with 100 ppm ethylene. After 24 hr, the first
is an important objective in nour grass breeding, and we try to true leaves were inoculated with Colletotrichum lagenarium.
obtain this by artificial testing. The progress depends on the Ethylene and water-treated control leaves exhibited high levels
variation and the heritability of the traits. Earlier investi- of lesion development, whereas, STS-treated plants had
gations have shown that there exists a great variation in snow significantly fewer lesions. Tests on culture media showed that
mold resistance and freezing resistance. The heritability was STS was not fungitoxic to C. lagenarium. STS is known to be an
studied in half sib families from polycross fields of Dactylis inhibitor of ethylene action. These data suggest that ethylene
gIomrsta.. The broad sense heritability (h 2 ) for the polycross may play a role in lesion development and tissue senescence in
progeny were 0.60 for freezing resistance, 0.49 for resistance cucumbers.
to Typhula ishikariensis, and 0.42 for resistance to Fusarium
nivale, which indicates good possibility for progress by selection
for these traits. 395
391
31AND
RESIDUAL BLAST RESISTANCE OF NEAR-ISOGENIC RICE LINES.
J.M. Bonman, T.I. Vergel de Bins, and D.J. Nackill, International
Rice Research Institute, P.O. Box 933, Manila,
Philippines.
THE REGULATION OF THE PEA DISEASE RESISTANCE RESPONSE GENE,
DRRG-49, VIA BOTH AP-l DNA ATTACHMENT SITES AND TOPOISONERASES
THEIR DNA CONSENSUS SITES. C. C. Chiang, A. Pettinger
and L. A. Hadwiger, Department of Plant Pathology, Washington
State University, Pullman, WA 99164.
Topoisomerase II consensus site clusters, which specify
A set of near-isogenic rice lines (NI) was developed through
backcrossing and recurrent selection for resistance to specific
isolates of Pyricularia oryzae. The recurrent parent, C039, is
widely susceptible to tropical races of the pathogen. Nls were
tested for complete resistance against a range of isolates, and
7 groups were identified based on reaction patterns. C039 and
Nls with different resistance genes were tested for partial
scaffold attachment, exist on regions 3' and 5' to the DRRG-
49 structural gene providing the potential for a chromosomal
loop. Also, AP-l sites are present that recognize specific
transcriptional proteins. In Fusarium solani challenged pea
endocarp, there is a sharp increase in topoisomerase I
activity and a release of chitosan heptamer. DRRC gene
regulation in terms of topography and torsional stresses of
chromosomal loops and by transcription factors, topoisomerases
1184 PHYTOPATHOLOGY