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bioRxiv · 10.1101/2020.05.22.111070

Evidence for dosage compensation in Coccinia grandis, a plant with a highly heteromorphic XY system

Fruchard, C.·Badouin, H.·Latrasse, D.·Devani, R. S.·Muyle, A.·Rhone, B.·Renner, S. S.·Banerjee, A. K.·Bendahmane, A.·Marais, G. A.
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Abstract

Some ~15.000 angiosperms are dioecious, but mechanisms of sex determination in plants remain poorly understood. In particular, how Y chromosomes evolve and degenerate, and whether dosage compensation evolves as a response, are matters of debate. Here we focus on Coccinia grandis, a dioecious cucurbit with the highest level of X/Y heteromorphy recorded so far. We identified sex-linked genes using RNA sequences from a cross and a model-based method termed SEX-DETector. Parents and F1 individuals were genotyped and the transmission patterns of SNPs then analysed. In the >1300 sex-linked genes studied, X-Y divergence was 0.13 - 0.17, and substantial Y degeneration is implied by an average Y/X expression ratio of 0.63 and an inferred gene loss on the Y of ~40%. We also found reduced Y gene expression being compensated by elevated expression of corresponding genes on the X and an excess of sex-biased genes on the sex chromosomes. Molecular evolution of sex-linked genes in C. grandis is thus comparable to that in Silene latifolia, another dioecious plant with a strongly heteromorphic XY system, and cucurbits are the fourth plant family in which dosage compensation is described, suggesting it might be common in plants.

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Fruchard, C., Badouin, H., Latrasse, D., Devani, R. S., Muyle, A., Rhone, B., Renner, S. S., Banerjee, A. K., Bendahmane, A., Marais, G. A.. 2020-05-23. Evidence for dosage compensation in Coccinia grandis, a plant with a highly heteromorphic XY system. https://doi.org/10.1101/2020.05.22.111070

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