GENETIC MALE-STERILITY IN WHEAT (TRITICUM-AESTIVUM-L) - REPRODUCTIVE CHARACTERISTICS AND POSSIBLE USE IN HYBRID WHEAT BREEDING

UC9109-9 is a genetic male-sterile wheat (T. aestivum) that was isolated at Davis [California, USA] from the cross of 2 fertile wheat varieties, D6301 and Ramona 50. The male-sterile plants were typical of genetic and cytoplasmic male-steriles, except that in a low proportion of the florets, the anthers were transformed to pistil-like structures. The pistilloid anthers were not fertile. UC9109-9 can be maintained by self-pollination, which occurs in about 5% of the florets. All progeny from selfed seeds were male-sterile. Aneuploidy was observed in populations derived from UC9109-9, but it was unrelated to male sterility. All F1 plants were fertile when UC9109-9 was used as a female parent in crosses with 8 fertile varieties. A low yield (about 30% of normal) of hybrid seeds was obtained in small-scale hybrid seed production trials, but improvements in seed production can be expected from manipulating growing conditions in the seed production field, or presumably by genetic improvement of the outcrossing mechanism in wheat.