Zhan Zhennan, Zhang Yanxia, Geng Kangqi, Xue Xiaobin, Deloire Alain, Li Dongmei, Wang Zhenping
School of Life Sciences, Ningxia University, Yinchuan 750021, China.
Ningxia Wine and Desertifcation Control Vocational and Technical College, Yinchuan 750199, China.
Foods. 2023 Nov 21;12(23):4191. doi: 10.3390/foods12234191.
Malic acid is the predominant organic acid in grape berries, and its content is affected by abiotic factors such as temperature (fruit zone microclimate) and water (vine water status). The objectives of this study were to explore the potential mechanisms behind the effects of vine water status on the biosynthesis and degradation of berry malic acid and the potential downstream effects on berry metabolism. This study was conducted over two growing seasons in 2021 and 2022, comprising three watering regimes: no water stress (CK), light water stress (LWS), and moderate water stress (MWS). Compared to CK, a significantly higher level of malic acid was found in berries from the MWS treatment when the berry was still hard and green (E-L 33) in both years. However, water stress reduced the malic acid content at the ripe berry harvest (E-L 38) stage. The activities of NAD-malate dehydrogenase (NAD-MDH) and pyruvate kinase (PK) were enhanced by water stress. Except for the E-L 33 stage, the activity of phosphoenolpyruvate carboxylase (PEPC) was reduced by water stress. The highest phosphoenolpyruvate carboxykinase (PEPCK) activity was observed at the berry veraison (E-L 35) stage and coincided with the onset of a decrease in the malate content. Meanwhile, the expression of was consistent with its enzyme activity. This study showed that water stress changed the content of some free amino acids (GABA, proline, leucine, aspartate, and glutamate), two of which (glutamate and GABA) are primary metabolites of the GABA pathway.
苹果酸是葡萄浆果中的主要有机酸，其含量受温度（果实区域微气候）和水分（葡萄藤水分状况）等非生物因素影响。本研究的目的是探究葡萄藤水分状况对浆果苹果酸生物合成和降解的影响背后的潜在机制，以及对浆果代谢的潜在下游影响。本研究在2021年和2022年的两个生长季节进行，包括三种浇水方式：无水分胁迫（CK）、轻度水分胁迫（LWS）和中度水分胁迫（MWS）。与CK相比，在两年中当浆果仍坚硬且呈绿色（E-L 33）时，MWS处理的浆果中苹果酸水平显著更高。然而，水分胁迫在成熟浆果收获（E-L 38）阶段降低了苹果酸含量。水分胁迫增强了NAD-苹果酸脱氢酶（NAD-MDH）和丙酮酸激酶（PK）的活性。除了E-L 33阶段外，水分胁迫降低了磷酸烯醇式丙酮酸羧化酶（PEPC）的活性。在浆果转色（E-L 35）阶段观察到最高的磷酸烯醇式丙酮酸羧激酶（PEPCK）活性，且与苹果酸含量开始下降同时出现。同时，[此处原文缺失具体基因或蛋白名称]的表达与其酶活性一致。本研究表明，水分胁迫改变了一些游离氨基酸（γ-氨基丁酸、脯氨酸、亮氨酸、天冬氨酸和谷氨酸）的含量，其中两种（谷氨酸和γ-氨基丁酸）是γ-氨基丁酸途径的主要代谢产物。
