Six blast‐resistant pearl millet genotypes, ICMB 93333, ICMB 97222, ICMR 06444, ICMR 06222, ICMR 11003 and IP 21187‐P1, were crossed with two susceptible genotypes, ICMB 95444 and ICMB 89111 to generate F1s, F2s and backcrosses, BC1P1 (susceptible parent × F1) and BC1P2 (resistant parent × F1) for inheritance study. The resistant genotypes were crossed among themselves in half diallel to generate F1s and F2s for test of allelism. The F1, F2 and backcross generations, and their parents were screened in a glasshouse against Magnaporthe grisea isolates Pg 45 and Pg 53. The reaction of the F1s, segregation pattern of F2s and BC1P1 derived from crosses involving two susceptible parents and six resistant parents revealed the presence of single dominant gene governing resistance in the resistant genotypes. No segregation for blast reaction was observed in the F2s derived from the crosses of resistant × resistant parents. The resistance reaction of these F2s indicated that single dominant gene conferring resistance in the six genotypes is allelic, that is same gene imparts blast resistance in these genotypes to M. grisea isolates.
Downy mildew (DM), caused by Sclerospora graminicola (Sacc.) Schröt., is a highly destructive and widespread disease in most pearl millet [Pennisetum glaucum (L.) R. Br.] growing areas of Asia and Africa. Breeding for DM resistance continues to be an integral part of genetic improvement of pearl millet at ICRISAT, Patancheru, India. For the identification of new and diverse sources of DM resistance, a pearl millet mini core collection comprising 238 accessions was screened against eight pathotypes (Sg 384, Sg 409, Sg 445, Sg 457, Sg 510, Sg 519, Sg 526, and Sg 542) of S. graminicola collected from different geographical locations in India. Significant differences for DM reaction were observed among pathotypes, mini core accessions, and their interactions. Of the 238 accessions, 68 accessions were resistant (≤10% DM incidence) to pathotype Sg 510 followed by 40 accessions resistant to Sg 457. Resistance to pathotypes Sg 519, Sg 526, Sg 384, Sg 445, and Sg 542 was observed in 15, 27, 29, 30, and 34 mini core accessions, respectively. Resistance to two or more pathotypes was observed in 62 accessions. Several of these accessions also exhibited desirable agronomic traits. The multiple‐pathotype‐resistant germplasm accessions having desirable agronomic characteristics and collected from different agro‐ecologies would be useful in breeding programs to develop pearl millet hybrids resistant to difficult‐to‐manage highly‐virulent pathotypes of S. graminicola.
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