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<p>Salinization threatens global crop productivity by compromising the growth, development, and ultimate yield of rice (<i>Oryza sativa</i> L.). In this study, we cloned and systematically investigated the function and physiological mechanism of <i>OsABA45</i> (<i>LOC_Os12g29400</i>), a gene encoding a GRAM domain-containing protein, in mediating rice responses to salt stress. Subcellular localization confirmed <i>OsABA45</i> as a cytoplasmic protein. Functional characterization of salinity tolerance at the seedling stage revealed that the survival rate of wild-type Nipponbare was 54.37%. By contrast, the <i>OsABA45</i> knockout lines exhibited a significantly enhanced survival rate of 74.94%, indicating markedly improved salt tolerance. Conversely, the overexpression lines showed a reduced survival rate of 35.78%, reflecting compromised tolerance. Furthermore, the survival rate of wild-type Caidao was 42.90%, whereas the complementation lines reached 80.06%. These results collectively demonstrate that <i>OsABA45</i> functions as a negative regulator of salt tolerance in rice. Interestingly, during seed germination and post-germination stages, <i>OsABA45</i> knockout and complementation lines displayed increased sensitivity to abscisic acid (ABA), while overexpression lines exhibited decreased sensitivity. Meanwhile, exogenous ABA application restored salt stress tolerance in the overexpression lines. Further analysis demonstrated that <i>OsABA45</i> knockout lines significantly upregulated the expression of key ABA biosynthesis genes, promoted endogenous ABA accumulation, and consequently enhanced salt tolerance, evidence <i>OsABA45</i> mediates salt stress responses by regulating the ABA biosynthesis pathway. Notably, <i>OsABA45</i> knockout and complemented lines also showed improved tolerance to ionic toxicity, osmotic stress, and oxidative stress, while overexpression lines exhibited reduced tolerance to these stresses. These results indicate that <i>OsABA45</i> plays vital roles in ABA signal responses and salt tolerance in rice. This study provides novel molecular targets and breeding strategies for improving salt tolerance.</p>

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OsABA45 Negatively Regulates Salt Stress Responses by Modulating Abscisic Acid Biosynthesis in Rice

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年2月8日

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  • Shanbin Xu,
  • Yuhang Zhao,
  • Jie Zheng,
  • Feishi Luan,
  • Shuangshuang Li,
  • Yuxuan Duan,
  • Tong Zhang,
  • Changlin Liu,
  • Meng Wu,
  • Jingguo Wang,
  • Hualong Liu,
  • Luomiao Yang,
  • Yan Jia,
  • Hongliang Zheng,
  • Wei Xin,
  • Detang Zou

摘要

Salinization threatens global crop productivity by compromising the growth, development, and ultimate yield of rice (Oryza sativa L.). In this study, we cloned and systematically investigated the function and physiological mechanism of OsABA45 (LOC_Os12g29400), a gene encoding a GRAM domain-containing protein, in mediating rice responses to salt stress. Subcellular localization confirmed OsABA45 as a cytoplasmic protein. Functional characterization of salinity tolerance at the seedling stage revealed that the survival rate of wild-type Nipponbare was 54.37%. By contrast, the OsABA45 knockout lines exhibited a significantly enhanced survival rate of 74.94%, indicating markedly improved salt tolerance. Conversely, the overexpression lines showed a reduced survival rate of 35.78%, reflecting compromised tolerance. Furthermore, the survival rate of wild-type Caidao was 42.90%, whereas the complementation lines reached 80.06%. These results collectively demonstrate that OsABA45 functions as a negative regulator of salt tolerance in rice. Interestingly, during seed germination and post-germination stages, OsABA45 knockout and complementation lines displayed increased sensitivity to abscisic acid (ABA), while overexpression lines exhibited decreased sensitivity. Meanwhile, exogenous ABA application restored salt stress tolerance in the overexpression lines. Further analysis demonstrated that OsABA45 knockout lines significantly upregulated the expression of key ABA biosynthesis genes, promoted endogenous ABA accumulation, and consequently enhanced salt tolerance, evidence OsABA45 mediates salt stress responses by regulating the ABA biosynthesis pathway. Notably, OsABA45 knockout and complemented lines also showed improved tolerance to ionic toxicity, osmotic stress, and oxidative stress, while overexpression lines exhibited reduced tolerance to these stresses. These results indicate that OsABA45 plays vital roles in ABA signal responses and salt tolerance in rice. This study provides novel molecular targets and breeding strategies for improving salt tolerance.