Plant Physiology Laboratory, CSIR(#) - National Botanical Research Institute, Lucknow, 226001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India; CSIR-National Botanical Research Institute, Lucknow, 226001, India.
Plant Physiol Biochem. 2023 Aug;201:107905. doi: 10.1016/j.plaphy.2023.107905. Epub 2023 Jul 26.
Four contrasting varieties of guar, RGC-1002 and RGC-1038, drought tolerant, while, Sarada and RGC-936, drought sensitive, were monitored in watered and drought. The water status, phenolics, plant anatomy and transcript level of genes related to anatomical traits were assessed. The study aimed to decipher the anatomical adaptations of guar plants in response to water stress. The physiological determinants, relative water content (RWC), water potential (ψ), and leaf membrane damage, declined under drought in all four varieties although, the decrement was lesser in the tolerant varieties. Furthermore, the tolerant cultivars subjected to water stress recorded higher accumulation of total phenolic content, anthocyanin and lignin, which efficiently scavenge the reactive oxygen species. The results suggest that the cultivars RGC-1002 and RGC-1038 are better able to resist drought-induced oxidative stress than Sarada and RGC-936. Moreover, leaf, petiole, stem and root anatomical traits viz. size of epidermal cell, parenchyma, width of cortex layer, and diameter of xylem vessels were narrowed in all the varieties although, the decrement was lesser in the tolerant varieties under drought. The expression analysis of genes revealed that drought-tolerant varieties showed enhanced mechanical support for water conduction by up-regulation of genes, Phenylalanine ammonia-lyase1 (PAL1), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), cinnamoyl-CoA reductase (CCR), caffeoyl-CoA O-methyltransferase (CCOMT), and cinnamyl-alcohol dehydrogenase (CAD6) in water stress conditions. The alterations in physio-anatomical, biochemical and gene expression traits in tolerant guar varieties enabled them to maintain steady nutrient transport while reducing the risk of embolisms and increasing water-flow resistance for better survival in water stressed conditions.
四种不同的瓜尔豆，RGC-1002 和 RGC-1038 具有耐旱性，而 Sarada 和 RGC-936 则对干旱敏感，在浇水和干旱条件下进行了监测。评估了水状态、酚类化合物、植物解剖结构以及与解剖结构特征相关的基因的转录水平。该研究旨在揭示瓜尔豆植物对水分胁迫的解剖适应机制。生理决定因素，包括相对含水量（RWC）、水势（ψ）和叶片膜损伤，在所有四种品种中都因干旱而下降，尽管在耐旱品种中下降幅度较小。此外，在受到水分胁迫时，耐旱品种记录到总酚含量、花青素和木质素的积累增加，这些物质可以有效地清除活性氧物质。结果表明，与 Sarada 和 RGC-936 相比，RGC-1002 和 RGC-1038 品种更能抵抗干旱诱导的氧化应激。此外，叶片、叶柄、茎和根的解剖结构特征，如表皮细胞、薄壁组织、皮层层宽度和木质部导管直径，在所有品种中都变窄，尽管在耐旱品种中下降幅度较小。基因表达分析表明，耐旱品种通过上调苯丙氨酸解氨酶 1（PAL1）、肉桂酸-4-羟化酶（C4H）、4-香豆酸辅酶 A 连接酶（4CL）、肉桂酰辅酶 A 还原酶（CCR）、咖啡酰辅酶 A O-甲基转移酶（CCOMT）和肉桂醇脱氢酶（CAD6）等基因，增强了对水分传导的机械支撑，从而在水分胁迫条件下表现出更好的适应性。在耐旱瓜尔豆品种中，这些生理-解剖、生化和基因表达特征的改变使它们能够在稳定养分运输的同时，降低栓塞风险并增加水流阻力，从而在水分胁迫条件下更好地生存。
