ICRISAT Archival Report 2006 - The seedlings of success in the ...

Milestone 5A.2.1.7: Comparisons of lines with single-QTL introgressions and QTL pyramided in two genetic
backgrounds for shoot fly resistance completed (HCS/BVSR/CTH/SPD, 2010)
To be reported subsequently
Output target 5A.3: Variation in sorghum grain mold pathogens and mycotoxin contamination risk assessed,
insect–host genotype-natural enemy interactions studied, and mechanisms of resistance to insect pests
identified (2010)
Activity 5A.3.1: Understanding host-pathogen-environment interaction in grain mold complex.
Milestone 5A.3.1.1: Major grain mold pathogens in sorghum growing states in India identified and their distribution
in relation to weather factors determined (RPT/RS, 2007)
Weather variables and grain mold pathogens: We conducted a Sorghum Grain Mold Resistance Stability Nursery
(SGMRSN) under the ICAR (AICSIP)-ICRISAT partnership project at five AICSIP centers Coimbatore, Dharwad,
Parbhani, Palem and Patancheru. The SGMRSN 2006 consisted of 50 entries (14 from NRCS and 36 from
ICRISAT). In addition to grain mold severity, data on weather variables (temperature, relative humidity and rainfall)
were also collected from these centers. Molded grain samples from these locations will be assayed for the presence
of various mold fungi and their frequency determined. From these and earlier data sets of the past four years, the
relationship between weather variables and frequency of mold pathogens at different locations will be determined.
RP Thakur and Rajan Sharma
Milestone 5A.3.1.2: Mycotoxin-producing isolates of Fusarium species associated with grain mold identified and
characterized and genetic resistance in relation to other major pathogens determined (2009)
Genetic resistance to sorghum grain mold: Identification of advanced sorghum breeding lines and germplasm
accessions with improved level of grain mold resistance has been a major focus towards developing grain moldresistant
hybrids. During 2006, a number of sorghum lines were screened in the glasshouse against individual
pathogens and in the grain mold nursery at ICRISAT, Patancheru, against general mold fungi.
Grain mold resistance in hybrid parental lines: Twenty sorghum genotypes [12 B-lines, 6 R-lines and 2
susceptible checks (CSH 9 and SPV 104)] were screened against three prominent pathogenic fungi, Fusarium
verticillioides (high fumonisins-producing strain), Curvularia lunata and Alternaria alternata under glasshouse
conditions. The experiment was conducted in a randomized complete block design (RCBD) with 20 genotypes × 3
fungi × 3 replications with 10 plants per replication. Panicles were inoculated at >80% flowering stage with conidial
suspensions of individual fungi and exposed to wetness for 48 h after inoculation. As the visual mold infection was
not clearly evident, we measured grain mold colonization at hard dough (HD), physiological maturity (PM) and on
threshed grain (TG) using the blotter method and 50 grains per replication at each grain development stage. In
general grain colonization by different fungi at HD was low and varied from 0 to 38%. However, grain colonization
at PM and of TG was quite variable for sorghum genotypes × pathogen combinations.
Grain colonization by F. verticillioides varied from 1 to 40% on test genotypes compared to 8−32% on susceptible
controls. Similarly, grain colonization by C. lunata varied from 11 to 92% on test genotypes compared to 51−95%
on susceptible controls, while that by A. alternata varied from 0 to 85% on test genotypes compared to 1−6% on
susceptible controls. Sorghum genotypes with resistance to single and multiple pathogens were identified. Four
genotypes (ICSB 352-5, ICSB 402-3, ICSB 370-2 and ICSR 89013-2) were resistant to F. verticillioides (0−9%
colonization); three genotypes (ICSB 402-3, ICSB 402-1-2 and SGMR 40-1-2-3) to C. lunata (7−17% colonization)
and five genotypes (ICSB 402-3, ICSB 402-1-2, IS 41397-3, SPV 462-3, SP 72519-1-3) to A. alternata (0−5%
colonization). Of these, only one genotype (ICSB 402-3) was resistant to all three pathogens; four (ICSB 370-1-5,
ICSV 96094-2, ICSR 89013-2 and ICSB 379-2) to both F. verticillioides and A. alternata and two (ICSB 402-1-2
and SGMR 40-1-2-3) to both C. lunata and A. alternata. This information would be useful for breeding grain mold
resistant hybrids and for studies on genetics and mechanism of resistance.
131