QUANTITATIVE TRAIT LOCI (QTLS) FOR POLLEN THERMOTOLERANCE DETECTED INMAIZE

Pollen thermotolerance is an important component of the adaptability o f crops to high temperature stress. The tolerance level of the differe nt genotypes in a population of 45 maize recombinant inbred lines was determined as the degree of injury caused by high temperature to polle n germinability (IPGG) and pollen tube growth (IPTG) in an in vitro as say. Both traits revealed quantitative variability and high heritabili ty. The traits were genetically dissected by the analysis of molecular markers using 184 mapped restriction fragment length polymorphisms (R FLPs). Significant genetic correlation between the markers and the tra it allowed us to identify a minimum number of five quantitative trait loci (QTLs) for IPGG and six QTLs for IPTG. Their chromosomal localiza tion indicated that the two characters are controlled by different set s of genes. In addition, IPGG and IPTG were shown to be basically inde pendent of the pollen germination ability and pollen tube growth rate under non-stress conditions. These results are discussed in relation t o their possible utilization in a breeding strategy for the improvemen t of thermotolerance in maize.