Plant Physiol:中科院遗传所程祝宽研究组发表植物减数分裂同源重
2016年3月9日，国际植物学顶级期刊《plant Physiology》杂志在线发表中国科学院遗传与发育生物学研究所程祝宽研究组在植物减数分裂同源重组研究的新研究文章。
减数分裂是维持物种遗传稳定性的同时，丰富个体遗传多样性的基础。在减数分裂过程中，同源染色体之间发生了一系列复杂的事件，包括同源染色体配对、联会、重组及分离等，其中重组是减数分裂的核心事件，而配对和联会是为重组的完成提供保障的。已有研究表明同源重组过程具有高度的保守性，但调控该过程蛋白的功能并非十分保守。
程祝宽研究组鉴定到两个保守的水稻DMC1基因：OsDMC1A和OsDMC1B。研究发现这两个基因功能冗余，任一单基因突变不影响水稻植株生长与发育。只有当它们同时突变后，才会导致减数分裂过程中大量单价体的形成。进一步研究表明，水稻DMC1功能缺失并不影响减数分裂同源重组早期蛋白的定位，但会使重组晚期蛋白OsHEI10在染色体上定位的大量减少。有趣的是，水稻DMC1基因突变并不影响减数分裂早期同源染色体的同源搜寻和配对，但会导致联会复合体的组装异常，这与酵母、小鼠、拟南芥等模式生物中的研究结果完全不同。相关研究结果为深入理解减数分裂同源重组调控的分子机制奠定了坚实基础。
水稻DMC1基因突变导致减数分裂细胞同源染色体联会异常
A.细线期花粉母细胞。B.偶线期花粉母细胞。C.粗线期花粉母细胞。在蛋白质免疫荧光共定位分析中，PAIR3的蓝色定位信号指示dmc1突变体中减数分裂前期的染色体。PAIR2的红色定位信号指示突变体中联会复合体轴向相关蛋白的组装状态。ZEP1的绿色定位信号指示突变体中联会复合体中央元件的组装状态。以箭头标记染色体上联会复合体部分形成的区域。标尺，5微米。
原文链接：
OsDMC1 is not required for homologous pairing in rICE meiosis
原文摘要：
Meiotic homologous recombination is pivotal to sexual reproduction. DMC1, a conserved recombinase, is involved in directing single end invasion (SEI) between interhomologs during meiotic recombination. In this study, we identified OsDMC1A and OsDMC1B, two closely related proteins in rice with high sequence similarity to DMC1 proteins from other species. Analysis of Osdmc1a and Osdmc1b Tos17 insertion mutants indicated that these genes are functionally redundant. Immunolocalization analysis revealed OsDMC1 foci occurred at leptotene, which disappeared from late pachytene chromosomes in wild-type meiocytes. According to cytological analyses, homologous pairing is accomplished in the Osdmc1a Osdmc1b double mutant, but synapsis is seriously disrupted. The reduced number of bivalents and abnormal OsHEI10 foci in Osdmc1a Osdmc1b establishes an essential role for OsDMC1 in crossover formation. In the absence of OsDMC1, early recombination events probably occur normally, leading to normal localization of γH2AX, PAIR3, OsMRE11, OsCOM1 and OsRAD51C. Moreover, OsDMC1 was not detected in pairing-defective mutants, such as pair2, pair3, Oscom1 and Osrad51c, while it was loaded onto meiotic chromosomes in zep1, Osmer3, Oszip4 and Oshei10. Taken together, these results suggest that during meiosis, OsDMC1 is dispensable for homologous pairing in rice, which is quite different from the DMC1 homologs identified so far in other organisms.
作者：程祝宽
