Sapkota Sirjan, Conner Joann A, Hanna Wayne W, Simon Bindu, Fengler Kevin, Deschamps Stéphane, Cigan Mark, Ozias-Akins Peggy
Department of Horticulture, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America.
Department of Crop and Soil Sciences, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America.
PLoS One. 2016 Mar 31;11(3):e0152411. doi: 10.1371/journal.pone.0152411. eCollection 2016.
Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae). The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus) and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass) is the apospory-specific genomic region (ASGR). Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH) and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.
无融合生殖，即通过种子进行克隆繁殖，是在禾本科（Poaceae）多个物种中发现的一种特性。控制鳞状狼尾草（Pennisetum squamulatum，同义词Cenchrus squamulatus）和毛臂形草（Cenchrus ciliaris，同义词Pennisetum ciliare，水牛草）无融合生殖的基因座是无孢子生殖特异性基因组区域（ASGR）。此前，基于荧光原位杂交（FISH）显示，ASGR在鳞状狼尾草和毛臂形草之间高度保守，但标记顺序相反，并且在其他无融合生殖的臂形草属/狼尾草属物种中，ASGR在ASGR携带染色体上的核型和位置都有所不同。通过电子转录本定位以及利用FISH对部分转录本的物理位置进行验证，我们发现鳞状狼尾草的ASGR携带染色体在ASGR之外与谷子和高粱的2号染色体是共线的。对鳞状狼尾草中先前未定位的ASGR携带染色体标记进行电子排序，有助于鉴定出一条回交系，该回交系的鳞状狼尾草ASGR携带染色体因γ射线辐照花粉而发生了结构变化。
