Tapping Pennisetum violaceum, a Wild Relative of Pearl Millet (Pennisetum glaucum), for Resistance to Blast (caused by Magnaporthe grisea) and Rust (caused by Puccinia substriata var. indica)

Abstract

Blast (Magnaporthe grisea) and rust (Puccinia substriata var. indica) are the two important foliar diseases of pearl millet (Pennisetum glaucum (L.) R. Br.) that can be best managed through host plant resistance. For identification of diverse sources of blast and rust resistance, 305 accessions of Pennisetum violaceum, a wild relative of pearl millet, were screened under greenhouse conditions against five pathotype-isolates of M. grisea and a local isolate of P. substriata var. indica collected from ICRISAT farm, Patancheru, India. Based on the mean blast score (1 to 9 scale), 17 accessions (IP 21525, 21531, 21536, 21540, 21594, 21610, 21640, 21706, 21711, 21716, 21719, 21720, 21721, 21724, 21987, 21988, and 22160) were found resistant (score ≤3.0) to all five pathotypes, and 24 accessions were resistant to four pathotypes of M. grisea. As there was variability for rust resistance within some accessions, individual rust-resistant (<5% severity) plants from 17 accessions were selected, grown in pots and advanced to next generation by selfing, and rescreened for three to four generations following pedigree selection to develop rust-resistant genetic stocks. Single plant selections from nine accessions (IP 21629, 21645, 21658, 21660, 21662, 21711, 21974, 21975, and 22038) were found highly resistant to rust (0% rust severity) after four generations of pedigree selection and subsequent screening. Some of the blast-resistant accessions and rust-resistant genetic stocks are being utilized in a prebreeding program at ICRISAT for introgressing resistance genes from the wild into the parental lines of cultivated and potential pearl millet hybrids and varieties.