State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou 510642, China.
J Integr Plant Biol. 2017 Sep;59(9):669-679. doi: 10.1111/jipb.12564. Epub 2017 Aug 23.
Hybrids between the indica and japonica subspecies of rice (Oryza sativa) are usually sterile, which hinders utilization of heterosis in the inter-subspecific hybrid breeding. The complex locus Sa comprises two adjacently located genes, SaF and SaM, which interact to cause abortion of pollen grains carrying the japonica allele in japonica-indica hybrids. Here we showed that silencing of SaF or SaM by RNA interference restored male fertility in indica-japonica hybrids with heterozygous Sa. We further used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-based genome editing to knockout the SaF and SaM alleles, respectively, of an indica rice line to create hybrid-compatible lines. The resultant artificial neutral alleles did not affect pollen viability and other agricultural traits, but did break down the reproductive barrier in the hybrids. We found that some rice lines have natural neutral allele Sa-n, which was compatible with the typical japonica or indica Sa alleles in hybrids. Our results demonstrate that SaF and SaM are required for hybrid male sterility, but are not essential for pollen development. This study provides effective approaches for the generation of hybrid-compatible lines by knocking out the Sa locus or using the natural Sa-n allele to overcome hybrid male sterility in rice breeding. © 2017 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.
籼稻和粳稻亚种间杂种通常是不育的，这阻碍了亚种间杂种优势在杂交育种中的利用。复杂的 Sa 基因座由两个紧密相邻的基因 SaF 和 SaM 组成，它们相互作用导致携带粳稻等位基因的花粉粒败育。在这里，我们通过 RNA 干扰沉默 SaF 或 SaM ，恢复了具有杂合 Sa 的籼粳亚种间杂种的雄性育性。我们进一步使用基于成簇规律间隔短回文重复序列（CRISPR）/Cas9 的基因组编辑，分别敲除了一个籼稻品系的 SaF 和 SaM 等位基因，以创建杂种亲和系。由此产生的人工中性等位基因不影响花粉活力和其他农艺性状，但打破了杂种的生殖障碍。我们发现一些水稻品系具有天然的中性等位基因 Sa-n，它与杂种中的典型粳稻或籼稻 Sa 等位基因兼容。我们的研究结果表明，SaF 和 SaM 是杂种雄性不育所必需的，但对花粉发育不是必需的。本研究通过敲除 Sa 基因座或利用天然 Sa-n 等位基因克服水稻杂种雄性不育，为产生杂种亲和系提供了有效的方法。
