Effect of gamete selection in improving of heat tolerance as demonstrated by shift in allele frequency in maize (Zea maize L.)

Abstract

Pollen genotype selection for genes expressed in both the haploid and diploid phases of the plant life cycle can lead to correlated responses detectable in the sporophyte. Here, Impact of pollen selection for heat tolerance was assessed in segregating population of maize. Two subsets of F1 were made among which one was self-fertilized with heat treated pollen grains while other set by normal pollen where no such selection was made that resulted in two F2 populations TF2 and CF2, respectively. The TF2 population recorded significantly higher mean values for pollen per anther (4646.78 ± 176.70) than that for control F2 population (3321.89 ± 164.91). In addition, the test F2 population recorded significantly higher seed yield per plant (2.02 ± 0.72 g) than that of test F2 population (1.38 ± 0.08 g) under heat stress. These two populations were also evaluated under normal condition to verify whether the TF2 population showed heat tolerance improvement has any impact on yield attributes. The result showed non-negative impact of pollen selection on performance of TF2 under normal condition. Thus, pollen selection could be used to selectively improve the trait of interest. The segregation analysis of SSR markers followed the expected Mendelian distribution in CF2 population whereas a significant deviation in allelic frequency was observed in TF2 population. These results clearly evidence that the gametophytic selection for heat tolerance in F1 generation had positive effect towards increasing the resistant alleles in F2 population of maize.