Cytogenetic comparison of heteromorphic and homomorphic sex chromosomes in Coccinia (Cucurbitaceae) points to sex chromosome turnover
Cytogenetic comparison of heteromorphic and homomorphic sex chromosomes in Coccinia (Cucurbitaceae) points to sex chromosome turnover
复制标题
DOI：
10.1007/s10577-017-9555-y
复制
发表时间：
2017-03
影响因子：
2.6
通讯作者：
Aretuza Sousa;J. Fuchs;S. Renner
中科院分区：
文献类型：
--
作者：
Aretuza Sousa;J. Fuchs;S. Renner
由于高通量测序数据和系统发育和分子细胞遗传学方法，我们对植物性染色体进化的理解正在迅速增加，这些方法使得推断从同型性染色体到异型性染色体的进化方向和步骤成为可能。在这里，我们集中在四种瓢虫属，一个属的25雌雄异株的物种，包括大瓢虫，物种与最大的已知植物Y染色体。根据该属的系统发育，我们选择了3个与C. grandisto测试了八个重复元件的分布，包括两个卫星，以及几个质体和线粒体探针，我们以前发现它们在C.大基因组此外，我们还测定了C值，并对两个物种进行了着丝粒特异性抗体的免疫染色实验（与C。grandis）。尽管没有显微镜下的染色体异型性，这三个物种的雄性细胞中的单对染色体积累了一些非常相同的重复序列，这些重复序列富集在C。grandisY染色体，指向旧的（以前的）性染色体或初期（新出现的）性染色体，即性染色体更替。一个144-bp的着丝粒卫星重复序列（CgCent），是allC的特征。除Y染色体外，大染色体在其他物种的所有着丝粒区域都非常丰富，表明Y染色体的着丝粒序列最近才发生分歧。
Our understanding of the evolution of plant sex chromosomes is increasing rapidly due to high-throughput sequencing data and phylogenetic and molecular-cytogenetic approaches that make it possible to infer the evolutionary direction and steps leading from homomorphic to heteromorphic sex chromosomes. Here, we focus on four species ofCoccinia, a genus of 25 dioecious species, includingCoccinia grandis, the species with the largest known plant Y chromosome. Based on a phylogeny for the genus, we selected three species close toC. grandisto test the distribution of eight repetitive elements including two satellites, and several plastid and mitochondrial probes, that we had previously found to have distinct accumulation patterns in theC. grandisgenome. Additionally, we determinedC-values and performed immunostaining experiments with (peri-)centromere-specific antibodies on two species (for comparison withC. grandis). In spite of no microscopic chromosomal heteromorphism, single pairs of chromosomes in male cells of all three species accumulate some of the very same repeats that are enriched on theC. grandisY chromosome, pointing to either old (previous) sex chromosomes or incipient (newly arising) ones, that is, to sex chromosome turnover. A 144-bp centromeric satellite repeat (CgCent) that characterizes allC. grandischromosomes except the Y is highly abundant in all centromeric regions of the other species, indicating that the centromeric sequence of the Y chromosome diverged very recently.