Abiotic Stress and Agro-Biotechnology Laboratory, Institute of Life Sciences, Nalco Square, Bhubaneswar 751023, Odisha, India.
Abiotic Stress and Agro-Biotechnology Laboratory, Institute of Life Sciences, Nalco Square, Bhubaneswar 751023, Odisha, India; and Corresponding author. Email:
Funct Plant Biol. 2020 Dec;48(1):72-87. doi: 10.1071/FP20089.
Soil salinisation is a major abiotic stress in agriculture, and is especially a concern for rice production because among cereal crops, rice is the most salt-sensitive. However, the production of rice must be increased substantially by the year 2050 to meet the demand of the ever growing population. Hence, understanding the biochemical events determining salt tolerance in rice is highly desirable so that the trait can be introduced in cultivars of interest through biotechnological intervention. In this context, an initial study on NaCl response in four Indica rice varieties showed a lower uptake of Na+ in the salt-tolerant Nona Bokra and Pokkali than in the salt-sensitive IR64 and IR29, indicating Na+ exclusion as a primary requirement of salt tolerance in the species. This was also supported by the following features in the salt-tolerant, but not in the -sensitive varieties: (1) highly significant NaCl-induced increase in the activity of PM-H+ATPase, (2) a high constitutive level and NaCl-induced threonine phosphorylation of PM-H+ATPase, necessary to promote its activity, (3) a high constitutive expression of 14-3-3 protein that makes PM-H+ATPase active by binding with the phosphorylated threonine at the C-terminal end, (4) a high constitutive and NaCl-induced expression of SOS1 in roots, and (5) significant NaCl-induced expression of OsCIPK 24, a SOS2 that phosphorylates SOS1. The vacuolar sequestration of Na+ in seedlings was not reflected from the expression pattern of NHX1/NHX1 in response to NaCl. NaCl-induced downregulation of expression of HKTs in roots of Nona Bokra, but upregulation in Pokkali also indicates that their role in salt tolerance in rice could be cultivar specific. The study indicates that consideration of increasing exclusion of Na+ by enhancing the efficiency of SOS1/PM-H+ATPase Na+ exclusion module could be an important aspect in attempting to increase salt tolerance in the rice varieties or cultivars of interest.
土壤盐渍化是农业中的一种主要非生物胁迫，尤其对水稻生产构成了关注，因为在谷类作物中，水稻对盐最为敏感。然而，到 2050 年，必须大幅增加水稻产量，以满足不断增长的人口需求。因此，深入了解决定水稻耐盐性的生化事件非常重要，以便通过生物技术干预将该特性引入有兴趣的品种中。在这种情况下，对四个籼稻品种在 NaCl 响应方面的初步研究表明，耐盐品种 Nona Bokra 和 Pokkali 对 Na+的吸收低于盐敏感品种 IR64 和 IR29，表明 Na+排除是该物种耐盐性的主要要求。这也得到了以下特征的支持：在耐盐品种中，但不在敏感品种中：（1）PM-H+ATPase 的活性在 NaCl 诱导下显著增加；（2）PM-H+ATPase 的高组成型水平和 NaCl 诱导的苏氨酸磷酸化，这对于促进其活性是必要的；（3）14-3-3 蛋白的高组成型表达，通过与 C 端磷酸化的苏氨酸结合使 PM-H+ATPase 具有活性；（4）根中 SOS1 的高组成型和 NaCl 诱导表达；（5）OsCIPK 24 的高组成型和 NaCl 诱导表达，这是一种磷酸化 SOS1 的 SOS2。幼苗中 Na+的液泡隔离并未反映 NHX1/NHX1 对 NaCl 的表达模式。在 Nona Bokra 的根中，NaCl 诱导的 HKTs 表达下调，但在 Pokkali 中上调，这表明它们在水稻耐盐性中的作用可能因品种而异。该研究表明，考虑通过提高 SOS1/PM-H+ATPase Na+排除模块的效率来增加 Na+的排除，可能是提高感兴趣的水稻品种或品种耐盐性的一个重要方面。
