Semigamy in Coix aquatica

In this abnormal form of fertilization the sperm nucleus penetrates the egg but does not fuse with the egg nucleus. The independent divisions of male and female nuclei will form paternal and maternal chimeral tissues in embryos, seedlings and plants. In Coix aquatica Roxb. (2n=10), in crosses involving stocks marked genetically (purple vs. green seedling base and purple vs. pearly white style) and cytologically (2n=10, 11, 12, etc.), the occasional observation of forking of the seedling stem with the constituents of forking, in some rare cases, differing genetically and cytologically, and resembling the male and female parents led to the identification of the occurrence of the phenomenon of semigamy. The male and female tissues so formed in most cases were 2n-2n, and in a few cases were presumed to be 2n-n since one of the constituents of forking grew slowly and produced fewer and weaker tillers all of which died before flowering. From the occurrence of apospory, apomixis and the functional nature of gametes with n=5 to 10 chromosomes, even on the male side, it might be expected that semigamy is of even wider occurrence in this species but escapes detection unless genetic markers are involved.

Panuganti N. Rao and D. S. Narayana


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