DETECTION OF QTLS CONTROLLING POLLEN GERMINATION AND GROWTH IN MAIZE

Pollen competitive ability, which represents the reproductive success of a pollen grain, is the result of various pre- and post-shedding com ponents. The genes controlling two of these, pollen germination and tu be elongation, measured in artificial conditions, were identified and their chromosomal localization established by RFLP analysis in a popul ation of recombinant inbred lines. Six regions were detected for polle n grain germination and seven for tube growth, which explained 45 per cent and 70 per cent, respectively, of the phenotypical variability of the traits. The results, interpreted together with those relating to in vivo germinability and tube growth rate, obtained in a previous exp eriment, suggested the existence of a system of timing of different se ts of genes controlling the gametophytic developmental stages.