Characterization of genic functional male sterility in brinjal and its expression in different genetic backgrounds

The present investigation reports four years of study on the expressivity of functional male sterility gene in the original mutant line UGS-1MS and in different genetic backgrounds. In polyhouse condition, anthers of most of the plants of UGS-1MS (88%) did not dehisce. In the open field conditions under two autumn-winter and one spring-summer seasons over two years only 63.5% plants on an average exhibited non-dehiscent anther character. However, percentage of open fruit set due to natural selfing was significantly lower in the plants showing either complete or partial anther dehisdence because anther dehiscence in these plants have occurred either very late or in few anthers only. Environmental variation for the trait indicates the role of environmentally sensitive modifier genes. Male fertility in all the six F₁ hybrids due either to complete or partial anther dehiscence suggested that functional sterility due to anther non-dehiscence was under the control of recessive genes. Wide range of heterosis for fruit yield ranging from 43.4 to 168.3 percent was manifested in the hybrids. Expressivity of the male sterile gene varied with the genotypes because different genotypes acquired gene causing the male sterility in a different way. For this reason, no male sterile genotype could be recovered in the F₂ populations of two hybrids, UGA-1MS x BCB-75 and UGA-1MS x BCB-45 and only one male sterile plant was observed in the F₂ population of UGA-1MS x BCB-14. Segregation pattern in 3 F₂ populations of UGA-1MS x BCB-15, UGA -IMS x BCB-1 and UGA-1MS x BCB-20, supported the good fit for 1:63 (male sterile: male fertile) segregation. It may be proposed that male sterility of UGA-IMS was controlled by one major recessive gene in combination with at least two modifier genes in recessive condition which may be symbolized as fms/fms ++. One line each in the UGA-1MS x BCB-15 line (designated as Bidhan UGA-1 MS-15) and UGA-1MS x BCB-20 line (designated as Bidhan UGA-1MS-20) could be identified which possessed comparatively high flowering propensity and expressed about 80% anther non-dehiscence character in field condition in F₄ generation holding enough promise for utilization in hybrid seed production.