New Sources of Resistance to Multiple Pathotypes of Sclerospora graminicola in the Pearl Millet Mini Core Germplasm Collection

Abstract

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