Prof. Michael Lenhard, Universität 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 place their pollen on different positions on pollinators’ bodies, such 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 organs in 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 the left-right axis. We are studying the molecular and genetic basis of the differences between the two classes of individuals for several examples with organ separation along one of the three axes mentioned. I will present an update of 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, i.e. haploid competition. To do so, we use transmission‑ratio distortion mapping to uncover naturally segregating haplotypes that affect pollen competitiveness in wild populations.