Nuclear male sterility systems in seed production of hybrid varieties

Hybrid seed is produced by the abnormal methods involving cytoplasmic male sterility, chemical sterilization, and nuclear male sterility. The last is the most common cause of male sterility; however, it has been less commonly used because special techniques are needed to produce a homogeneous male sterile block for hybrid seed production. This review will examine recent knowledge of nuclear male sterility, describe its manipulation in hybrid seed production, and attempt to define, its future role.