Selective fertilization in maize, Zea mays L. III. Independence of gametophyte factors on superiority of pollen grains from F1 plants.

Abstract

In the previous reports, it was shown that the superiority of pollen grains from F1 plants in selective fertilization of maize existed. Clarification, however, was needed for possible linkage of any gametophyte factor(s) to the marker gene and for the factor responsible for maintaining the superiority of F1's pollen grains. At first, the present study dealt with conducting two kinds of back-crossing, all possible selfing of four F1s, and all possible crossing among F1s. The existence of gametophyte factor(s) relating to the marker gene could not be found out in back-crossing used F1s as pollen parents. In selfing in part, crossing, and another type of back-crossing, however, aberrant segregation ratios of the marker gene were found out in particular pollination combinations. Secondly, pronounced superiority of F1's pollen grains was well confirmed in the mixed-pollination experiments (YAMADA 1982). It was, moreover, shown that the superiority of pollen grains from Fl plants in selective fertilization is due to the grains per se which are produced by the sporophyte of F1 in heterozygosity.