Prof. Michael Lenhard, University of Potsdam

Flowering plants have evolved many adaptations to promote outbreeding. In one group of such adaptations, individuals in a population fall into two classes that deposit their pollen at different positions on pollinators’ bodies, so that the pollen can be efficiently picked up by the stigmas of the other class and vice versa. This is based on the reciprocal spatial separation of male and female reproductive organs in the flowers of the two classes. Such separation of the reproductive organs can occur along the proximo-distal axis of the flower, or in dorso-ventrally asymmetrical flowers, also along the dorso-ventral or left-right axis. We are studying the molecular and genetic basis of the differences between the two classes of individuals using several examples where organ separation occurs along one of the three axes mentioned. I will present an update on our recent progress, highlighting commonalities in the underlying genomic architecture and insights into the molecular control mechanisms.

In a second part, I will relate these findings to ongoing work in the outcrossing Brassicaceae species Capsella grandiflora, where we study natural variation in what happens after pollen is deposited on the stigma—that is, haploid competition. To do so, we use transmission-ratio distortion mapping to identify naturally segregating haplotypes that influence pollen competitiveness in wild populations.