S1 families as a source of beneficial alleles for breeding drought tolerant maize genotypes

As water resources for agronomic use become more limiting development of drought tolerant genotypes become increasingly more important. In maize, under drought stress conditions, an increase in the length of anthesis- silking interval and a decrease of grain yield is observed. Different strategies have been proposed to overcome negative effects of drought on maize. Breeders at Maize Research Institute (MRI) have created and used adapted drought tolerant population - DTP-A (DTP79xDTP12xDwarf), that was shown to be a good source of drought tolerance for locally adapted germplasm. In this research s1 families from DTP-A x B84 were scored for anthesis-silking interval and genotyped with SSR markers using BSA approach, with the aim to create a new gene pool for breeding drought tolerant hybrids. SSR analysis was performed in order to identify putative genomic segments and allele pattern differences responsible for expression of ASI, thus providing an insight into the genetic structure of s1 families. Four SSR loci, different in allelic structure between short and long ASI families, were identified. The main characteristic of these differences was the presence or absence of DTP79/DTP12 alleles. It seems that combination of several different genes and alleles influence ASI expression, with DTP79 alleles being beneficial and DTP12 alleles detrimental. Two chromosome regions identified in this work were congruent with qASI regions reported in Maize Genetics and Genomics Database. Clustering revealed that all sASI families grouped with DTP79, but one of the long ASI grouped with these genotypes too. This could indicate that, although total participation of DTP79 genome was similar in all the analyzed families, only a small portion of its genome influence anthesis-silking interval.