Laboratoire de Biométrie et Biologie Évolutive UMR 5558, Université Lyon 1, CNRS, F-69622 Villeurbanne, France.
Laboratory of Applied Genomics and Crop Breeding, All-Russia Research Institute of Agricultural Biotechnology, Moscow 127550, Russia.
Genome Res. 2020 Feb;30(2):164-172. doi: 10.1101/gr.251207.119. Epub 2020 Feb 7.
-derived tetrahydrocannabinol (THC) production is increasing very fast worldwide. is a dioecious plant with XY Chromosomes, and only females (XX) are useful for THC production. Identifying the sex chromosome sequence would improve early sexing and better management of this crop; however, the genome projects have failed to do so. Moreover, as dioecy in the Cannabaceae family is ancestral, sex chromosomes are potentially old and thus very interesting to study, as little is known about old plant sex chromosomes. Here, we RNA-sequenced a family (two parents and 10 male and female offspring, 576 million reads) and performed a segregation analysis for all genes using the probabilistic method SEX-DETector. We identified >500 sex-linked genes. Mapping of these sex-linked genes to a genome assembly identified the largest chromosome pair being the sex chromosomes. We found that the X-specific region (not recombining between X and Y) is large compared to other plant systems. Further analysis of the sex-linked genes revealed that has a strongly degenerated Y Chromosome and may represent the oldest plant sex chromosome system documented so far. Our study revealed that old plant sex chromosomes can have large, highly divergent nonrecombining regions, yet still be roughly homomorphic.
大麻素的衍生四氢大麻酚（THC）在全球范围内的产量增长非常迅速。大麻是一种具有 XY 染色体的雌雄异株植物，只有雌性（XX）植物可用于 THC 生产。鉴定性染色体序列将有助于早期性别鉴定和更好地管理这种作物；然而，大麻基因组项目未能做到这一点。此外，由于大麻科植物的雌雄异株是原始的，因此性染色体可能非常古老，研究起来非常有趣，因为人们对古老的植物性染色体知之甚少。在这里，我们对大麻属（两个亲本和 10 个雄性和雌性后代，5.76 亿个读数）进行了 RNA 测序，并使用概率方法 SEX-DETector 对所有基因进行了分离分析。我们鉴定出了>500 个与性别相关的基因。将这些与性别相关的基因映射到一个大麻属基因组组装上，确定了最大的一对染色体是性染色体。我们发现，与其他植物系统相比，X 染色体的特有区域（X 和 Y 之间不重组）很大。对与性别相关的基因的进一步分析表明，大麻属具有强烈退化的 Y 染色体，可能代表迄今为止记录到的最古老的植物性染色体系统。我们的研究表明，古老的植物性染色体可能具有较大的、高度分化的非重组区域，但仍然大致同源。
