Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy.
Institute for Sustainable Plant Protection, National Research Council (IPSP-CNR), 10135 Torino, Italy.
Plant Sci. 2021 Feb;303:110729. doi: 10.1016/j.plantsci.2020.110729. Epub 2020 Oct 25.
MicroRNAs regulate plant development and responses to biotic and abiotic stresses but their impact on water use efficiency (WUE) is poorly known. Increasing WUE is a major task in crop improvement programs aimed to meet the challenges posed by the reduction in water availability associated with the ongoing climatic change. We have examined the physiological and molecular response to water stress of tomato (Solanum lycopersicum L.) plants downregulated for miR396 by target mimicry. In water stress conditions, miR396-downregulated plants displayed reduced transpiration and a less then proportional decrease in the photosynthetic rate that resulted in higher WUE. The increase in WUE was associated with faster foliar accumulation of abscisic acid (ABA), with the induction of several drought-protective genes and with the activation of the jasmonic acid (JA) and γ-aminobutyric acid (GABA) pathways. We propose a model in which the downregulation of miR396 leads to the activation of a complex molecular response to water stress. This response acts synergistically with a set of leaf morphological modifications to increase stomatal closure and preserve the efficiency of the photosynthetic activity, ultimately resulting in higher WUE.
MicroRNAs 调控植物的发育和对生物及非生物胁迫的响应，但它们对水分利用效率（WUE）的影响知之甚少。提高 WUE 是作物改良计划的主要任务之一，旨在应对与气候变化相关的水资源减少所带来的挑战。我们通过靶向模拟研究了番茄（Solanum lycopersicum L.）植株 miR396 下调对水分胁迫的生理和分子响应。在水分胁迫条件下，miR396 下调的植株表现出蒸腾作用降低和光合速率不成比例下降，从而导致 WUE 提高。WUE 的增加与 ABA 在叶片中更快的积累有关，与几种抗旱保护基因的诱导以及与茉莉酸（JA）和γ-氨基丁酸（GABA）途径的激活有关。我们提出了一个模型，即 miR396 的下调导致对水分胁迫的复杂分子响应的激活。这种响应与一组叶片形态学修饰协同作用，以增加气孔关闭并保持光合作用效率，最终导致更高的 WUE。
