Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, Olomouc 779 00, Czech Republic; Polish Academy of Sciences, Institute of Plant Genetics, Strzeszyńska 34, Poznań 60-479, Poland.
Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, Olomouc 779 00, Czech Republic.
J Adv Res. 2023 Nov;53:75-85. doi: 10.1016/j.jare.2023.01.002. Epub 2023 Jan 9.
Meiotic recombination is one of the most important processes of evolution and adaptation to environmental conditions. Even though there is substantial knowledge about proteins involved in the process, targeting specific DNA loci by the recombination machinery is not well understood.
This study aims to investigate a wheat recombination hotspot (H1) in comparison with a "regular" recombination site (Rec7) on the sequence and epigenetic level in conditions with functional and non-functional Ph1 locus.
The DNA sequence, methylation pattern, and recombination frequency were analyzed for the H1 and Rec7 in three mapping populations derived by crossing introgressive wheat line 8.1 with cv. Chinese Spring (with Ph1 and ph1 alleles) and cv. Tähti.
The H1 and Rec7 loci are 1.586 kb and 2.538 kb long, respectively. High-density mapping allowed to delimit the Rec7 and H1 to 19 and 574 bp and 593 and 571 bp CO sites, respectively. A new method (ddPing) allowed screening recombination frequency in almost 66 thousand gametes. The screening revealed a 5.94-fold higher recombination frequency at the H1 compared to the Rec7. The H1 was also found out of the Ph1 control, similarly as gamete distortion. The recombination was strongly affected by larger genomic rearrangements but not by the SNP proximity. Moreover, chromatin markers for open chromatin and DNA hypomethylation were found associated with crossover occurrence except for the CHH methylation.
Our results, for the first time, allowed study of wheat recombination directly on sequence, shed new light on chromatin landmarks associated with particular recombination sites, and deepened knowledge about role of the Ph1 locus in control of wheat recombination processes. The results are suggesting more than one recombination control pathway. Understanding this phenomenon may become a base for more efficient wheat genome manipulation, gene pool enrichment, breeding, and study processes of recombination itself.
减数分裂重组是进化和适应环境条件的最重要过程之一。尽管人们对参与该过程的蛋白质有了大量的了解，但重组机制对特定 DNA 基因座的靶向作用还不是很清楚。
本研究旨在比较功能和非功能 Ph1 基因座条件下，在序列和表观遗传水平上，研究小麦重组热点（H1）与“常规”重组位点（Rec7）。
通过与含有 Ph1 和 ph1 等位基因的 8.1 导入系与春小麦 cv.Chinese Spring 和 cv.Tähti 杂交衍生的三个作图群体，分析 H1 和 Rec7 的 DNA 序列、甲基化模式和重组频率。
H1 和 Rec7 位点分别长 1.586 kb 和 2.538 kb。高密度作图将 Rec7 和 H1 分别限定在 19 和 574 bp 和 593 和 571 bp CO 位点。一种新的方法（ddPing）允许在近 66000 个配子中筛选重组频率。筛选结果表明，H1 的重组频率比 Rec7 高 5.94 倍。H1 也被发现不在 Ph1 的控制之下，与配子变形类似。重组受到较大基因组重排的强烈影响，但不受 SNP 近邻的影响。此外，与同源重组发生相关的开放染色质和 DNA 低甲基化的染色质标记被发现除了 CHH 甲基化之外。
我们的结果首次允许直接在序列上研究小麦重组，为与特定重组位点相关的染色质标志提供了新的认识，并加深了对 Ph1 基因座在控制小麦重组过程中的作用的了解。结果表明存在不止一种重组控制途径。了解这一现象可能成为更有效地进行小麦基因组操作、基因库富集、育种以及研究重组本身过程的基础。
