Raz Amir, Dahan-Meir Tal, Melamed-Bessudo Cathy, Leshkowitz Dena, Levy Avraham A
Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel.
Department of Plant Science, MIGAL Galilee Research Institute, Kiryat Shmona, Israel.
Front Plant Sci. 2021 Feb 4;11:635139. doi: 10.3389/fpls.2020.635139. eCollection 2020.
Meiotic recombination is the main driver of genetic diversity in wheat breeding. The rate and location of crossover (CO) events are regulated by genetic and epigenetic factors. In wheat, most COs occur in subtelomeric regions but are rare in centromeric and pericentric areas. The aim of this work was to increase COs in both "hot" and "cold" chromosomal locations. We used Virus-Induced gene Silencing (VIGS) to downregulate the expression of recombination-suppressing genes and and of epigenetic maintenance genes and during meiosis. VIGS suppresses genes in a dominant, transient and non-transgenic manner, which is convenient in wheat, a hard-to-transform polyploid. F1 hybrids of a cross between two tetraploid lines whose genome was fully sequenced (wild emmer and durum wheat), were infected with a VIGS vector ∼ 2 weeks before meiosis. Recombination was measured in F2 seedlings derived from F1-infected plants and non-infected controls. We found significant up and down-regulation of CO rates along subtelomeric regions as a result of silencing either , or during meiosis. In addition, we found up to 93% increase in COs in XRCC2-VIGS treatment in the pericentric regions of some chromosomes. Silencing showed no effect on CO. Overall, we show that CO distribution was affected by VIGS treatments rather than the total number of COs which did not change. We conclude that transient silencing of specific genes during meiosis can be used as a simple, fast and non-transgenic strategy to improve breeding abilities in specific chromosomal regions.
减数分裂重组是小麦育种中遗传多样性的主要驱动力。交叉（CO）事件的速率和位置受遗传和表观遗传因素调控。在小麦中，大多数CO发生在亚端粒区域，但在着丝粒和着丝粒周围区域很少见。这项工作的目的是增加“热点”和“冷点”染色体位置的CO。我们使用病毒诱导基因沉默（VIGS）在减数分裂期间下调重组抑制基因和表观遗传维持基因的表达。VIGS以显性、瞬时和非转基因的方式抑制基因，这在小麦这种难以转化的多倍体中很方便。在减数分裂前约2周，用VIGS载体感染两个基因组已完全测序的四倍体系（野生二粒小麦和硬粒小麦）杂交产生的F1杂种。在来自F1感染植株和未感染对照的F2幼苗中测量重组情况。我们发现，由于在减数分裂期间沉默、或，亚端粒区域的CO速率出现了显著的上调和下调。此外，我们发现，在某些染色体的着丝粒周围区域，XRCC2-VIGS处理使CO增加了93%。沉默对CO没有影响。总体而言，我们表明CO分布受VIGS处理的影响，而CO的总数没有变化。我们得出结论，减数分裂期间特定基因的瞬时沉默可作为一种简单、快速且非转基因的策略，用于提高特定染色体区域的育种能力。
