Haplotype frequencies at the miR156 and miR172 transcript regions show a significant response to divergent recurrent selection for vegetative phase change in maize

Abstract

Sweet corn (Zea mays L). plants that transition from juvenility to the adult phase earlier during development are generally more resistant to common rust (Puccinia sorghi), a disease that causes substantial yield loss in sweet corn. This developmental transition is called vegetative phase change (VPC). VPC is regulated in part by miR156 and miR172. We found that natural variation at the miR156 and miR172 transcript regions are important in determining variation in the timing of VPC. We sequenced the miR156 and miR172 transcript regions in populations originating from the same source population and divergently selected for eight generations for early and late VPC. For both the miR156 and miR172 transcript regions we detected four distinct haplotypes. Overall and individual haplotype frequencies showed significant responses to selection for both early and late VPC. These data contribute to the identification of important loci involved in VPC. Understanding the genetic basis for VPC will facilitate maize breeding aimed at combining early VPC with other desirable traits.