Ngo Ngwe Florence, Siljak-Yakovlev Sonja
Biodiversity Division, Institute of Agricultural Research for Development, Yaoundé 2123, Cameroon.
Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique Evolution, 91190 Gif-sur-Yvette, France.
Plants (Basel). 2023 Jan 4;12(2):228. doi: 10.3390/plants12020228.
Yams ( spp.) are a pantropical genus located worldwide that constitute an important source of nutrients and pharmaceutical substances. Some crop species are widely grown in West Africa. One species that is mainly cultivated in Cameroon is This is a dioecious root crop whose sex-determining system was unknown until now. To address the possible presence of sex chromosomes in we performed a karyotype characterization of male and female individuals using classical and molecular cytogenetic approaches. It was determined that 2 = 40 was the most common number of chromosomes in all of the investigated samples. One chromosome pair was longer than the others in the chromosome set and was a heteromorph in male and homomorph in female individuals. This pair corresponded to sex chromosomes, and we also confirmed this with molecular cytogenetic experiments. The results of chromomycin banding revealed the presence of strong positive signals on this chromosome pair. The signals, corresponding to GC-rich DNA regions, were similar in size on the chromosomes of the female individuals, whereas they were different in size in the male individuals. This size difference in the GC-rich heterochromatin regions was also apparent in the interphase nuclei as one small and one large fluorescent spot. The results of the in situ hybridization experiment showed that these chromomycin positive signals on the sex chromosomes also corresponded to the 35S rDNA cluster. The mean 2C DNA value (genome size) obtained for was 0.71 pg (±0.012), which represents a small genome size. We found no difference in the genome size between the male and female individuals. The results of this study contribute to increasing our knowledge of sex determination in (standard sex-determining XX/XY system) and may have some agronomic applications.
薯蓣属植物是一个分布于全球泛热带地区的属，是重要的营养物质和药物来源。一些作物品种在西非广泛种植。喀麦隆主要种植的一个品种是[品种名称未给出]。这是一种雌雄异株的块根作物，其性别决定系统至今尚不清楚。为了探究[品种名称未给出]中可能存在的性染色体，我们使用经典和分子细胞遗传学方法对雌雄个体进行了核型分析。结果确定，在所研究的所有样本中，2n = 40是最常见的染色体数目。在染色体组中，有一对染色体比其他染色体长，在雄性个体中是异形的，在雌性个体中是同形的。这一对染色体对应于性染色体，我们还通过分子细胞遗传学实验证实了这一点。放线菌素带型分析结果显示，在这对染色体上存在强烈的阳性信号。这些信号对应于富含GC的DNA区域，在雌性个体的染色体上大小相似，而在雄性个体中大小不同。在间期核中，富含GC的异染色质区域的这种大小差异也表现为一个小的和一个大的荧光点。原位杂交实验结果表明，性染色体上的这些放线菌素阳性信号也对应于35S rDNA簇。[品种名称未给出]的平均2C DNA值（基因组大小）为0.71 pg（±0.012），这代表着较小的基因组大小。我们发现雌雄个体之间的基因组大小没有差异。本研究结果有助于增加我们对[品种名称未给出]性别决定（标准的XX/XY性别决定系统）的了解，并且可能具有一些农艺学应用。
