A new cytoplasmic‐nuclear male sterility system in pearl millet

Abstract

AbstractAmong the cytoplasmic‐nuclear male sterility (CMS) systems reported in pearl millet, Pennisetum glaucum (L.) R. Br., the Am= A4 system produces the highest frequency of male‐sterile hybrids. A CMS source identified in a large‐seeded gene pool (LSGP) was compared with the A4 system. Seven diverse restorer lines of the A4 system produced hybrids with 81A4 that were all fertile (pollen‐shedding score 4 and 68–89% 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 diverse composites made with 81A4 had 10–35% plants that had good fertility (> 50% selfed seedset). In comparison, no plant of any topcross hybrid with the isonuclear line having LSGP cytoplasm exceeded 20% selfed seedset, and it was rare for a plant to exceed even 10% selfed seedset. These differential fertility restoration patterns of hybrids indicate that the LSGP cytoplasm represents a CMS system that is different from the A4 and, by implication, from all those reported to date. This new CMS system is designated A5.