Kim Sun Ha, Shim Kyu-Chan, Lee Hyun-Sook, Jeon Yun-A, Adeva Cheryl, Luong Ngoc Ha, Ahn Sang-Nag
Department of Agronomy, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, South Korea.
Crop Breeding Division, National Institute of Crop Science, Wanju-Gun, South Korea.
Front Plant Sci. 2022 Sep 20;13:985559. doi: 10.3389/fpls.2022.985559. eCollection 2022.
In rice, low-temperature germinability (LTG) is essential for stable stand establishment using the direct seeding method in temperate and high-altitude areas. Previously, we reported that the quantitative trait locus is associated with LTG. is also associated with tolerance to several abiotic stresses, such as salt and osmotic conditions. In this study, map-based cloning and sequence analysis indicated that is allelic to (), which encodes cytochrome P450 D2 (LOC_Os01g10040) involved in brassinosteroid (BR) biosynthesis. Sequence comparison of the two parental lines, Hwaseong and (IRGC 105491), revealed five single nucleotide polymorphisms (SNPs) in the coding region. Three of these SNPs led to missense mutations in , whereas the other two SNPs were synonymous. We evaluated two T-DNA insertion mutants, , overexpression (-OE) and knockdown (-KD) mutants of , with the Dongjin genetic background. -KD plants showed a decrease in LTG and grain size. In contrast, -OE plants showed an increase in grain size and LTG. We also examined the expression levels of several BR signaling and biosynthetic genes using the T-DNA insertion mutants. Gene expression analysis and BR application experiments demonstrated that BR enhanced the seed germination rate under low-temperature conditions. These results suggest that is associated with the regulation of LTG and improving grain size. Thus, may be a suitable target for rice breeding programs to improve rice yield and LTG.
在水稻中，低温发芽能力（LTG）对于在温带和高海拔地区采用直播法稳定立苗至关重要。此前，我们报道过数量性状基因座与LTG相关。它还与对几种非生物胁迫的耐受性相关，如盐和渗透条件。在本研究中，基于图谱的克隆和序列分析表明，它与编码参与油菜素内酯（BR）生物合成的细胞色素P450 D2（LOC_Os01g10040）的（）等位。两个亲本系华城和（IRGC 105491）的序列比较揭示了编码区的五个单核苷酸多态性（SNP）。其中三个SNP导致中的错义突变，而另外两个SNP是同义的。我们评估了具有东津遗传背景的两个T-DNA插入突变体、的过表达（-OE）和敲低（-KD）突变体。-KD植株的LTG和粒重降低。相反，-OE植株的粒重和LTG增加。我们还使用T-DNA插入突变体检测了几个BR信号传导和生物合成基因的表达水平。基因表达分析和BR施用实验表明，BR提高了低温条件下的种子发芽率。这些结果表明，与LTG的调控和粒重的改善有关。因此，可能是水稻育种计划中提高水稻产量和LTG的合适靶点。
