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This project aimed at investigating the mechanisms of sex-determination in flowering plants as well as the evolutionary mechanisms that lead to the differentiation of the X and Y chromosomes. Because they have evolved sex chromosomes multiple times independently and more or less recently, plants provide a much more complete view of sex chromosome evolution than animal systems. Modification of sexuality is also one of the most important goals for breeding of plant crops.This project focuses on the mechanisms of sex determination in Caucasian persimmon (Diospyros lotus), a diploid tree with sex genetics consistent with heterogametic males (XY). We have assembled male-specific sequence contigs by cataloging short nucleotide sequence patterns unique to males from whole genome sequencing. Expression analysis using mRNA and smRNA-Seq and molecular evolution analyses allowed for the identification of potential candidate genes.We identified an inverted repeat male-specific gene, OGI, which displays high conservation among dioecious species in the Diospyros genus and demonstrated that OGI encodes a small RNA targeting the female-specific MeGI transcription factor. Our results cast light on the organization of a plant Y chromosome and provide a working model for sex determination in Diospyros species. |