Sorghum Diseases in India

Abstract:
Studies on the biology of long smut of sorghum
caused by Tolyposporium ehrenbergii
J.G.M. Njuguna, Plant Pathologist, Kenya National
Agricultural Research Center, Muguga,
PO Box 30148, Nairobi, Kenya; L.K. Mughogho,
ICRISAT Center, Patancheru, Andhra Pradesh
502 324, India; V. Guiragossian, JP 31 SAF-
GRAD, PO Box 30786, Nairobi, Kenya; and R.O.
Odhiambo, National Agricultural Research
Center, Muguga, PO Box 30148, Nairobi, Kenya.
Heads of sorghum plants growing in the greenhouse
were inoculated with either chlamydospores
or sporidia. A comparison of sporidia
with chlamydospores as inoculum showed
sporidia to be more efficient in causing infection.
Plants inoculated with sporidia just before the
heads emerged from the boot became infected,
as did plants inoculated when heads were partially
emerged. Infection did not occur on plants
with fully emerged heads. Of the nine sorghum
genotypes screened for resistance against long
smut in the greenhouse experiments, ICSV 212
and QL 3 showed the least long smut sori.
Abstract:
Inheritance of resistance to systemic infection
by downy mildew in sorghum
M.F. Beninati, ICRISAT Mali Program, BP 34,
Bamako (via Paris), Mali.
Parents, F1, F2, and BCF generations from 60 resistant
x susceptible or resistant x resistant
crosses, involving 12 resistant parents, were
screened (uncontrolled dosages) for resistance
to systemic infection of downy mildew in 1986
and 1987. Field screening data from crosses of
resistant parents IS 2266, IS 7215, and IS
18757(QL 3) with susceptible parents IS 643 and
IS 18433 are reported. IS 2266 appears to possess
a single dominant gene for resistance, while F2
and BCF1 data for crosses with IS 7215 suggest
that resistance is controlled by the interaction
between one dominant and one recessive locus.
Resistance in IS 18757 appears to be controlled
by at least two loci, and F1 data indicate incomplete
dominance. Further studies may be neces-
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sary to verify these findings and to determine
the number of different loci involved in resistance
in the lines under study.
Abstract:
Sorghum yellow banding virus (SYBV), a new
polyhedral virus on Sorghum spp
L. M. Giorda, and R. W. Toler, Department of
Plant Pathology and Microbiology, Texas A&M
University/College Station, TX 77843, USA, and
G.N. Odvody, Associate Professor Plant Pathology,
Texas A&M University, Agricultural Experiment
Station, Rt. 2 Box 589, Corpus Christi, TX
78410, USA.
Symptoms of virus activity include yellow
streaks that coalesce into bands, followed by
chlorosis, stunting, and eventual death of the
plant. The host range of SYBV includes Setaria
italica, Sorghum bicolor, S. sudanense, S. halepense,
Zea mays, and sorghum x sudangrass hybrids.
The sorghum cultivar, QL 3 India, immune to
strains of sugarcane mosaic virus and maize
dwarf mosaic virus, was susceptible to SYBV.
QL 3 developed chlorotic streaking, bands, and
severe necrosis. The size of virus particles from
purified preparations ranged from 25 to 32 µm
(mode: 27 µm). Antisera prepared against purified
virus reached a titer of 1/2048 using the
Ouchterlony gel double immunodiffusion test.
Infected sap from sorghum and maize were
tested against panicum mosaic virus (PMV),
PMV-SAD (the St. Augustine strain of PMV),
brome mosaic virus, cucumber mosaic virus,
maize chlorotic mottle virus, and maize chlorotic
dwarf virus antisera with negative results. Purified
particles of SYBV formed a single band on
sucrose gradient and in cesium chloride continuous-density
gradient. Viral fractions had a
260/280 ratio of 1.53. Virions of SYBV were
buoyant with a density of 1.386 g cm* 3 , compared
to 1.316 of tobacco mosaic virus. A single
protein band with molecular weight of 29 kd
was identified, using SDS-PAGE analysis. The
RNA from purified SYBV, under nondenaturing
conditions, migrate as five bands in 21.3% agarnose
gel with 10 mM sodium phosphate buffer
pH 7.0 and 0.02% SDS. The major band was approximately
1.8 kb and the others ranged between
038 and 1.3 kb when compared to RNA