MITOCHONDRIAL DNA-RFLP ANALYSIS DISTINGUISHES NEW CMS SOURCES IN PEARL-MILLET (PENNISETUM-GLAUCUM (L.) R BR.)

Restriction fragment length polymorphism (RFLP) of mitochondrial (mt) DNA provides a rapid and effective method to assess heterogeneity amon g male sterile cytoplasms. Six isonuclear A-lines (81 A(1), with Tift 23A(1), cytoplasm, ICMA 88001 (= 81A(v)) with Violaceum cytoplasm, 81A (=81A(4)) with monodii = violaceum cytoplasm, Pb 310A(2) and Pb 311A( 2) with A(2) cytoplasm from L 66A, and Pb 406A(3) with A(3) cytoplasm from L 67A), nine cytoplasmic male-sterility sources from Large-Seeded Genepool (LSGP 6, LSGP 14, LSGP 17, LSGP 22, LSGP 28, LSGP 36, LSGP 4 3, LSGP 55 and LSGP 66) and two each from Early Genepool (EGP 33 and E GP 15) and Population Varieties (PV 1 and PV 2) were characterized for variation in their mitochondrial genomes following Southern blot hybr idizations using homologous (pearl millet 13.6 kb, 10.9 kb, 9.7 kb and 4.7 kb clones) and heterologous (maize atp6 and coxl clones) mitochon drial DNA (mtDNA) probes. Following cluster analysis based on similari ty indices for the RFLP banding patterns observed, we identified seven cytoplasmic groups within LSGP. Two (LSGP 43 and LSGP 66) of these we re quite distinct from each other as well as from other cytoplasms. Th is clearly indicates that besides serving as a source of diversity for agronomic and adaptation traits, broad-based gene pools can also prov ide diverse sources of cytoplasmic male sterility. These new CMS sourc es were also compared with standard CMS systems and cytoplasm-specific restriction fragments were identified.