Kim Ga-Eun, Sung Jwakyung
Deptment of Crop Science, Chungbuk National University, Cheong-ju, Republic of Korea.
Front Plant Sci. 2023 Sep 7;14:1219610. doi: 10.3389/fpls.2023.1219610. eCollection 2023.
Drought is one of the most stressful environments limiting crop growth and yield throughout the world. Therefore, most efforts have been made to document drought-derived genetic and physiological responses and to find better ways to improve drought tolerance. The interaction among them is unclear and/or less investigated. Therefore, the current study is to find a clue of metabolic connectivity among them in rice root experiencing different levels of drought condition. We selected 19 genes directly involved in abscisic acid (ABA) metabolism (6), suberization (6), and aquaporins (AQPs) activity (7) and analyzed the relatively quantitative gene expression using qRT-PCR from rice roots. In addition, we also analyzed proline, chlorophyll, and fatty acids and observed cross-sectional root structure (aerenchyma) and suberin lamella deposition in the endodermis. All drought conditions resulted in an obvious development of aerenchyma and two- to fourfold greater accumulation of proline. The limited water supply (-1.0 and -1.5 MPa) significantly increased gene expression (ABA metabolism, suberization, and AQPs) and developed greater layer of suberin lamella in root endodermis. In addition, the ratio of the unsaturated to the saturated fatty acids was increased, which could be considered as an adjusted cell permeability. Interestingly, these metabolic adaptations were an exception with a severe drought condition (hygroscopic coefficient, -3.1 MPa). Accordingly, we concluded that the drought-tolerant mechanism in rice roots is sophisticatedly regulated until permanent wilting point (-1.5 MPa), and ABA metabolism, suberization, and AQPs activity might be independent and/or concurrent process as a survival strategy against drought.
干旱是限制全球作物生长和产量的最具胁迫性的环境因素之一。因此,人们已做出诸多努力来记录干旱引发的遗传和生理反应,并寻找提高耐旱性的更好方法。它们之间的相互作用尚不清楚且/或研究较少。因此,本研究旨在寻找处于不同干旱程度的水稻根系中它们之间代谢连通性的线索。我们选择了19个直接参与脱落酸(ABA)代谢(6个)、栓质化(6个)和水通道蛋白(AQP)活性(7个)的基因,并使用qRT-PCR分析了水稻根系中这些基因的相对定量表达。此外,我们还分析了脯氨酸、叶绿素和脂肪酸,并观察了根的横截面结构(通气组织)以及内皮层中栓质层的沉积情况。所有干旱条件均导致通气组织明显发育,脯氨酸积累增加两到四倍。有限供水(-1.0和-1.5 MPa)显著增加了基因表达(ABA代谢、栓质化和AQP),并使根内皮层的栓质层更厚。此外,不饱和脂肪酸与饱和脂肪酸的比例增加,这可被视为细胞通透性的一种调节。有趣的是,这些代谢适应在严重干旱条件(吸湿系数,-3.1 MPa)下是个例外。因此,我们得出结论,水稻根系的耐旱机制在达到永久萎蔫点(-1.5 MPa)之前受到复杂调控,ABA代谢、栓质化和AQP活性可能是作为抗旱生存策略的独立和/或并行过程。