National Research Council (CNR), Institute of Agricultural Biology and Biotechnology (IBBA), Rome Unit, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
National Research Council (CNR), Institute of Agricultural Biology and Biotechnology (IBBA), Via Alfonso Corti 12, 20133 Milan, Italy.
Int J Mol Sci. 2023 Aug 11;24(16):12668. doi: 10.3390/ijms241612668.
Class 2 KNOX homeobox transcription factors (KNOX2) play a role in promoting cell differentiation in several plant developmental processes. In , they antagonize the meristematic KNOX1 function during leaf development through the modulation of phytohormones. In , three KNOX2 genes belonging to the subclass ( or ) redundantly works upstream of a cytokinin-signaling module to control the symbiotic root nodule formation. Their possible role in the response to abiotic stress is as-of-yet unknown. We produced transgenic lines, in which the expression of four genes was knocked down by RNA interference. When tested for response to water withdrawal in the soil, RNAi lines displayed a lower tolerance to drought conditions compared to the control lines, measured as increased leaf water loss, accelerated leaf wilting time, and faster chlorophyll loss. Reanalysis of a transcriptomic drought stress experiment via cluster analysis and gene co-expression networks pointed to a possible role of MtKNOX3-like transcription factors in repressing a proline dehydrogenase gene (), specifically at 4 days after water withdrawal. Proline measurement and gene expression analysis of transgenic RNAi plants compared to the controls confirmed the role of genes in inhibiting proline degradation through the regulation of the gene.
类 2 KNOX 同源盒转录因子 (KNOX2) 在几个植物发育过程中促进细胞分化中发挥作用。在 ，它们通过植物激素的调节拮抗叶发育过程中的分生组织 KNOX1 功能。在 ，属于 子类（或）的 3 个 KNOX2 基因在细胞分裂素信号模块的上游冗余工作，以控制共生根瘤的形成。它们在应对非生物胁迫中的可能作用尚不清楚。我们产生了转基因 株系，其中四个 基因的表达通过 RNA 干扰被敲低。在测试土壤中水分胁迫的反应时，与对照株系相比，RNAi 株系对干旱条件的耐受性较低，表现为增加的叶片水分损失、加速叶片萎蔫时间和更快的叶绿素损失。通过聚类分析和基因共表达网络对 干旱胁迫转录组实验的重新分析表明，MtKNOX3 类转录因子可能在抑制脯氨酸脱氢酶基因 () 方面发挥作用，特别是在水分胁迫后 4 天。与对照相比，转基因 RNAi 植物的脯氨酸测量和基因表达分析证实了 基因通过调节 基因抑制脯氨酸降解的作用。
