Detection of genetic factors controlling pollen–style interaction in maize

In order to detect loci specifically related to pollen–style interaction in maize, linkage analysis to RFLP markers was performed on a population of recombinant inbred lines, the pollen of which was used to pollinate female plants of two different genotypes: the F1 from which the recombinant inbred population was derived (‘self female’) and a genetically unrelated hybrid genotype (‘cross female’). Besides pollen grain germinability and pollen tube growth rate on the two females, pollen general competitive ability and pollen specific competitive ability for both traits were evaluated, following the procedure used to estimate general and specific combining ability, applied to the pollen-style genetic combination instead of to the hybrid genetic combination. A clear advantage of recombinant inbred line pollen, in terms of germination and early growth, was revealed on self female tissues whereas an inverse effect was detected for tube growth rate: tube growth, until fertilization, was faster on the female of unrelated genotype. Linkage analysis to molecular markers (RFLP) of germinability and of tube growth rate on the two stylar genotypes identified nine QTLs for the first trait on the self and eight on the cross female; four chromosome regions 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.