A NEW CYTOPLASMIC-NUCLEAR MALE-STERILITY SYSTEM IN PEARL-MILLET

Among the cytoplasmic-nnclear male sterility (CMS) systems reported in pearl millet, Pennisetum glaucum (L.) R. Br., the A(m) = A(4) system produces the highest frequency of male-sterile hybrids. A CMS source i dentified in a large-seeded gene pool (LSGP) was compared with the A(4 ) system. Seven diverse restorer lines of the A, system produced hybri ds with 8lA(4) that were all fertile (pollen-shedding score 4 and 68-8 9% selfed seedset). In contrast, all the hybrids of these inbreds made with the isonuclear line with the LSGP cytoplasm were sterile (pollen -shedding score 1 and 0-3% selfed seedset). Topcross hybrids of four d iverse composites made with 8lA(4) had 10-35% plants that had good fer tility (> 50% selfed seedset). In comparison, no plant of any topcross hybrid with the isonnclear line having LSGP cytoplasm exceeded 20% se lfed seedset, and it was rare for a plant to exceed even 10% selfed se edset. These differential fertility restoration patterns of hybrids in dicate that the LSGP cytoplasm represents a CMS system that is differe nt from the A(4) and, by implication, from all those reported to date. This new CMS system is designated A(5).