DETECTION OF GENETIC-FACTORS CONTROLLING POLLEN-STYLE INTERACTION IN MAIZE

In order to detect loci specifically related to pollen-style interacti on in maize, linkage analysis to RFLP markers was performed on a popul ation of recombinant inbred lines, the pollen of which was used to pol linate female plants of two different genotypes: the F-1 from which th e recombinant inbred population was derived ('self female') and a gene tically unrelated hybrid genotype ('cross female'). Besides pollen gra in germinability and pollen tube growth rate on the two females, polle n general competitive ability and pollen specific competitive ability for both traits were evaluated, following the procedure used to estima te general and specific combining ability, applied to the pollen-style genetic combination instead of to the hybrid genetic combination. A c lear advantage of recombinant inbred line pollen, in terms of germinat ion and early growth, was revealed on self female tissues whereas an i nverse effect was detected for tube growth rate: tube growth, until fe rtilization, was faster on the female of unrelated genotype. Linkage a nalysis to molecular markers (RFLP) of germinability and of tube growt h rate on the two stylar genotypes identified nine QTLs for the first trait on the self and eight on the cross female; four chromosome regio ns for tube growth rate were detected on the self and 11 on the cross style. Most of the general competitive ability effects were localized in the regions where QTLs for germinability or pollen tube growth were detected, in particular on the cross female; on the contrary, most of the loci for pollen specific competitive ability effects proved to be localized in different chromosome regions.