Division of Plant Physiology, ICAR-Indian Agricultural Research Institute, New Delhi, India.
Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India.
Plant Physiol Biochem. 2021 Aug;165:161-172. doi: 10.1016/j.plaphy.2021.05.013. Epub 2021 May 21.
Understanding the reproductive stage salinity stress tolerance is a key target for breeding stress tolerant rice genotypes. Nitrate and ammonium are equally important nitrogen forms utilized by rice. We evaluated nitrate and ammonium assimilation during reproductive stage in control and salinity (10dSm using NaCl) stressed rice plants. Osmotic stress tolerant rice genotype Shabhagidhan (SD) and high yielding yet osmotic and salinity stress sensitive genotype Pusa sugandh-5 (PS5) were evaluated. Salinity stress was given to plants during panicle emergence and flag leaves was collected after 1d, 3d 5d, 7d, 9d,12d and 15d after anthesis. Reproductive stage salinity stress resulted in decrease of membrane stability, relative water content and osmotic potential of rice plants. Reproductive stage salinity stress decreased the expression of nitrate reductase (OsNIA), nitrite reductase (OsNiR), Glutamine synthetase (OsGLN1.1, OsGLN1.2, OsGLN2) and glutamate synthase/GOGAT (OsFd-GOGAT, OsNADH-GOGAT) in flag leaves. In response to stress, SD showed better stress tolerance than PS5 in terms of higher yield stability. Variety SD showed higher leaf nitrate and ammonium content and maintained comparatively higher nitrate and ammonia metabolism enzyme activity than PS5. Salinity stress upregulated the activity of glutamate dehydrogenase enzyme and indirectly contributed to the higher proline content and maintenance of favourable osmotic potential in SD. Expression of GS2 which has role in photo respiratory ammonia assimilation was upregulated by salinity stress in PS5 in comparison to SD. Rice genotype showing better induction of nitrogen assimilatory genes will be more tolerant to reproductive stage salinity stress.
了解生殖阶段盐胁迫耐受性是培育耐盐水稻基因型的关键目标。硝酸盐和铵盐是水稻同样重要的氮源形式。我们评估了对照和盐胁迫（10dSm 使用 NaCl）下水稻生殖阶段的硝酸盐和铵盐同化。评估了耐渗透胁迫的水稻基因型 Shabhagidhan（SD）和高产量但渗透和盐胁迫敏感的基因型 Pusa sugandh-5（PS5）。在穗出期对植物施加盐胁迫，并在开花后 1d、3d、5d、7d、9d、12d 和 15d 收集旗叶。生殖期盐胁迫导致水稻植株膜稳定性、相对含水量和渗透势降低。生殖期盐胁迫降低了旗叶中硝酸还原酶（OsNIA）、亚硝酸盐还原酶（OsNiR）、谷氨酰胺合成酶（OsGLN1.1、OsGLN1.2、OsGLN2）和谷氨酸合酶/谷氨酸转氨酶（OsFd-GOGAT、OsNADH-GOGAT）的表达。在应激条件下，SD 在产量稳定性方面比 PS5 表现出更好的应激耐受性。品种 SD 表现出较高的叶片硝酸盐和铵盐含量，并维持相对较高的硝酸盐和氨代谢酶活性，优于 PS5。盐胁迫上调了谷氨酸脱氢酶的活性，间接导致 SD 中脯氨酸含量较高，维持了有利的渗透势。与 SD 相比，PS5 中参与光呼吸氨同化的 GS2 基因的表达在盐胁迫下上调。表现出更好的氮同化基因诱导的水稻基因型将更能耐受生殖期盐胁迫。
