Department of Botany, Panjab University, Chandigarh, 160014, India.
World Vegetable Center, South Asia, ICRISAT Campus, 502 324, Hyderabad, AP, India.
Sci Rep. 2019 May 24;9(1):7788. doi: 10.1038/s41598-019-44163-w.
Rising global temperatures are proving to be detrimental for the agriculture. Hence, strategies are needed to induce thermotolerance in food crops to sustain the food production. GABA (γ-aminobutyric acid), a non-protein amino acid, can partially protect plants from high-temperature stress. This study hypothesises that declining GABA concentrations in the cells of heat-stressed mungbean plants increases the heat-sensitivity of reproductive function. Mungbean plants were grown in a natural, outdoor environment (29.3/16.1 ± 1 °C as mean day/night temperature, 1350-1550 µmol m s light intensity, 60-65% as mean relative humidity) until the start of the reproductive stage. Subsequently, two temperature treatments were imposed in a controlled environment-control (35/23 °C) and heat stress (45/28 °C)-at about 800 µmol m s light intensity and 65-70% as mean relative humidity, until pod maturity. In heat-stressed (HS) plants, endogenous GABA concentrations in leaf and anther samples had declined by 49 and 60%, respectively, and to a much lesser degree in the plants, exogenously supplemented with 1 mM GABA. The reproductive function of GABA-treated heat-stressed plants improved significantly in terms of pollen germination, pollen viability, stigma receptivity and ovule viability, compared to untreated HS controls. In addition, GABA-treated heat-stressed plants had less damage to membranes, photosynthetic machinery (chlorophyll concentration, chlorophyll fluorescence, RuBisCO activity were functionally normal) and carbon assimilation (sucrose synthesis and its utilisation) than the untreated HS controls. Leaf water status improved significantly with GABA application, including enhanced accumulation of osmolytes such as proline and trehalose due to increase in the activities of their biosynthetic enzymes. GABA-treated heat-stressed plants produced more pods (28%) and seed weight (27%) plant than the untreated controls. This study is the first to report the involvement of GABA in protecting reproductive function in mungbean under heat stress, as a result of improved leaf turgor, carbon fixation and assimilation processes, through the augmentation of several enzymes related to these physiological processes.
全球气温上升对农业造成了不利影响。因此，需要采取策略诱导粮食作物耐热性，以维持粮食生产。γ-氨基丁酸（GABA）是一种非蛋白氨基酸，它可以部分保护植物免受高温胁迫。本研究假设受热胁迫的绿豆细胞中 GABA 浓度的降低会增加生殖功能对高温的敏感性。绿豆植株在自然户外环境中生长（平均日/夜温度为 29.3/16.1°C，光照强度为 1350-1550 μmol m s，平均相对湿度为 60-65%），直到生殖阶段开始。随后，在控制环境中对其进行两种温度处理-对照（35/23°C）和热应激（45/28°C）-光照强度约为 800 μmol m s，平均相对湿度为 65-70%，直到豆荚成熟。在热应激（HS）植株中，叶片和花粉囊样品中的内源性 GABA 浓度分别下降了 49%和 60%，而用 1mM GABA 外源处理的植株中 GABA 浓度下降程度要小得多。与未处理的 HS 对照相比，用 GABA 处理的热应激植株的花粉萌发、花粉活力、柱头可接受性和胚珠活力显著提高。此外，与未处理的 HS 对照相比，用 GABA 处理的热应激植株的细胞膜、光合作用（叶绿素浓度、叶绿素荧光、RuBisCO 活性功能正常）和碳同化（蔗糖合成及其利用）损伤较小。用 GABA 处理后，叶片水势显著改善，由于其生物合成酶活性的提高，脯氨酸和海藻糖等渗透物质的积累也得到增强。与未处理的对照相比，用 GABA 处理的热应激植株产生的豆荚（28%）和种子重量（27%）更多。本研究首次报道了 GABA 通过增强与这些生理过程相关的几种酶的活性，改善绿豆叶片膨压、碳固定和同化过程，从而在热胁迫下保护绿豆生殖功能的作用。
