State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an 710048, China.
College of Horticulture, Northwest A & F University, Xianyang 712100, China.
Int J Mol Sci. 2022 Nov 26;23(23):14817. doi: 10.3390/ijms232314817.
Auxin regulates plant growth and development, as well as helps plants to survive abiotic stresses, but the effects of auxin on the growth of alkaline-stressed rice and the underlying molecular and physiological mechanisms remain unknown. Through exogenous application of IAA/TIBA, this study explored the physiological and molecular mechanisms of alkaline stress tolerance enhancement using two rice genotypes. Alkaline stress was observed to damage the plant growth, while exogenous application of IAA mitigates the alkaline-stress-induce inhibition of plant growth. After application of exogenous IAA to alkaline-stressed rice, dry shoot biomass, foliar chlorophyll content, photosynthetic rate in the two rice genotypes increased by 12.6-15.6%, 11.7-40.3%, 51.4-106.6%, respectively. The adventitious root number, root surface area, total root length and dry root biomass in the two rice genotypes increased by 29.3-33.3%, 26.4-27.2%, 42.5-35.5% and 12.8-33.1%, respectively. The accumulation of HO, MAD were significantly decreased with the application of IAA. The activities of CAT, POD, and SOD in rice plants were significantly increased by exogenous application of IAA. The expression levels of genes controlling IAA biosynthesis and transport were significantly increased, while there were no significant effects on the gene expression that controlled IAA catabolism. These results showed that exogenous application of IAA could mitigate the alkaline-stress-induced inhibition of plant growth by regulating the reactive oxygen species scavenging system, root development and expression of gene involved in IAA biosynthesis, transport and catabolism. These results provide a new direction and empirical basis for improving crop alkaline tolerance with exogenous application of IAA.
生长素调节植物的生长和发育，帮助植物应对非生物胁迫，但生长素对碱性胁迫下水稻生长的影响及其潜在的分子和生理机制尚不清楚。本研究通过外源施加 IAA/TIBA，利用两个水稻品种探讨了增强碱性胁迫耐受性的生理和分子机制。结果表明，碱性胁迫会损害植物的生长，而外源施加 IAA 可减轻碱性胁迫对植物生长的抑制作用。外源施加 IAA 后，两个水稻品种的地上部干生物量、叶片叶绿素含量、光合速率分别增加了 12.6-15.6%、11.7-40.3%、51.4-106.6%。两个水稻品种的不定根数、根表面积、总根长和根干重分别增加了 29.3-33.3%、26.4-27.2%、42.5-35.5%和 12.8-33.1%。外源施加 IAA 可显著降低 HO 和 MAD 的积累。CAT、POD 和 SOD 的活性在水稻植株中外源施加 IAA 后显著增加。控制 IAA 生物合成和转运的基因表达水平显著增加，而控制 IAA 分解代谢的基因表达水平没有显著变化。这些结果表明，外源施加 IAA 可以通过调节活性氧清除系统、根系发育和参与 IAA 生物合成、转运和分解代谢的基因表达来减轻碱性胁迫对植物生长的抑制作用。这些结果为利用外源施加 IAA 提高作物的耐碱性提供了新的方向和经验依据。
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