Changes in gene during sex chromosome evolution in the dioecious plant Silene latifolia

We developed a high-throughput method to identify genes with sex-linked inheritance patterns in the pant Silene latifolia (white campion), and identified several hundred new genes on the sex chromosome. We found that many X-linked genes have retained counterparts on the Y, and that Y-linked alleles have low expression compared with X-linked ones, and have accumulated many more deleterious changes. We also, for the first time in a plant, estimated the proportion of genes with sex-linked patterns that indicate that the Y chromosome copies have been lost (the commonest situation in mammals); in our plant, loss of Y-linked genes appears to be rare. Although this young Y chromosome retains many genes, we showed that these already have slightly reduced gene expression and are accumulating changes likely to impair functions.

The study also developed genetic markers within identified genes on all 12 S. latifolia chromosomes and a genetic map of all the chromosomes. A comparative map was made in S. vulgaris, greatly expanding the number of sex-linked S. latifolia genes mapped in this relative, and illuminating the evolution of the S. latifolia sex chromosomes.

A research student also published discoveries of several new sex-linked genes, and another research student published population genetic results on DNA sequence diversity in natural populations, in addition to 2 papers studying evidence for local adaptation involving the sex chromosomes, and for selection in the plant’s genome. We also published analyses of codon usage bias in Silene latifolia, providing the first evidence that selection on the codons used affects the sequences of highly expressed genes in this plant. With the post-doc, I published a review of sex chromosome evolution.

Developed high-throughput method to identify genes with sex-linked inheritance
Identified several hundred new genes on a plant sex chromosome
Found that many X-linked genes have retained counterparts on the Y
Y-linked alleles have low expression compared with X-linked ones, and have accumulated many more deleterious changes.
Provided the first estimate of the proportion of genes in a dioecious plant with the Y chromosome copies lost