Gan Quan, Song Fengshun, Zhang Chuanzhong, Han Zhongmin, Teng Bin, Lin Cuixiang, Gu Dongfang, Wang Jiajia, Pei Huan, Wu Ji, Fang Jun, Ni Dahu
Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, China.
Key Laboratory of Rice Genetics and Breeding in Anhui Province, Hefei, China.
Plant Cell Environ. 2023 May;46(5):1610-1628. doi: 10.1111/pce.14550. Epub 2023 Feb 5.
Increasing rice yield has always been one of the primary objectives of rice breeding. However, panicle degeneration often occurs in rice-growing regions and severely curbs rice yield. In this study, we obtained a new apical panicle degeneration mutant, which induces a marked degeneration rate and diminishes the final grain yield. Cellular and physiological analyses revealed that the apical panicle undergoes programmed cell death, accompanied by excessive accumulations of peroxides. Following, the panicle degeneration gene OsCAX1a was identified in the mutant, which was involved in Ca transport. Hydroponics assays and Ca quantification confirmed that Ca transport and distribution to apical tissues were restricted and over-accumulated in the mutant sheath. Ca transport between cytoplasm and vacuole was affected, and the reduced Ca content in the vacuole and cell wall of the apical panicle and the decreased Ca absorption appeared in the mutant. RNA-Seq data indicated that the abnormal CBL (calcineurin b-like proteins) pathway mediated by deficient Ca might occur in the mutant, resulting in the burst of ROS and programmed cell death in panicles. Our results explained the key role of OsCAX1a in Ca transport and distribution and laid a foundation to further explore the genetic and molecular mechanisms of panicle degeneration in rice.
提高水稻产量一直是水稻育种的主要目标之一。然而，水稻种植区经常发生穗退化现象，严重限制了水稻产量。在本研究中，我们获得了一个新的穗尖退化突变体，其诱导了显著的退化率并降低了最终籽粒产量。细胞和生理分析表明，穗尖经历了程序性细胞死亡，同时伴随着过氧化物的过度积累。随后，在该突变体中鉴定出穗退化基因OsCAX1a，其参与钙转运。水培试验和钙定量分析证实，突变体中钙向穗尖组织的转运和分布受到限制，且在叶鞘中过度积累。细胞质与液泡之间的钙转运受到影响，突变体穗尖液泡和细胞壁中的钙含量降低，钙吸收减少。RNA测序数据表明，突变体中可能发生了由缺钙介导的异常CBL（类钙调神经磷酸酶B蛋白）途径，导致穗中活性氧爆发和程序性细胞死亡。我们的结果解释了OsCAX1a在钙转运和分布中的关键作用，为进一步探索水稻穗退化的遗传和分子机制奠定了基础。
