Pollen Degradation and Inheritance of Male Sterility in Three Mutants in Tomato, Lycopersicon esculentum Mill, cv. First

Abstract

Three types of male sterile mutants were induced by irradiation of dry tomato seeds of cv. First with gamma rays. The mutants are characterized by : a) pollen degradation process, b) morphorogical differences in the floral organs and c) anther colour. Their genetic systems were also investigated. One group of male sterile mutants developed normal pistil and stamen with yellow anther, and thus this type was indistinguishable from the non-irradiated (control) plants even at flowering stage. Pollen degradation of this type (T-1) became evident at micro-sporogenesis. The second one was morphologically distinguishable by an exserted style because of a degenerating anther which became yellow-brown acropetally. Pollen degradation of this type (T-2) became evident around meiosis stage. The third one developed normal pistil and stamen with yellow anther, similar to those in T-1. However, the pistil became longer than the stamen a few days before anthesis, and top of staminal-corn split at anthesis so that the stigma was disclosed. Pollen degradation of this type (T-3) became evident from tetrad to early microspore stages. For each type, when heterozygous plants, Msms, was selfed, fertile and sterile progenies in the M2 and M3 generations segregated at a ratio of 3 : 1. The fertile and sterile progenies from a testcross between sterile, msms, and heterozygous plants, Msms, segregated at a ratio of 1 : 1. These results indicate that the three types of male sterility are controlled by a single recessive gene.