Ali Muhammad Moaaz, Anwar Raheel, Rehman Rana Naveed Ur, Ejaz Shaghef, Ali Sajid, Yousef Ahmed F, Ercisli Sezai, Hu Xiaobo, Hou Youming, Chen Faxing
State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.
Institute of Subtropical Fruits, Fujian Agriculture and Forestry University, Fuzhou, China.
Front Plant Sci. 2022 Oct 20;13:1039360. doi: 10.3389/fpls.2022.1039360. eCollection 2022.
Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. Some loquat cultivars have high acid content which seriously affect the quality of fruit and reduce the value of commodity. Consequently, studying the physiological mechanism of sugar-acid metabolism in loquat can clarify the mechanism of their formation, accumulation and degradation in the fruit. Minerals application has been reported as a promising way to improve sugar-acid balance of the fruits. In this study, loquat trees were foliar sprayed with 0.1, 0.2 and 0.3% borax, and changes in soluble sugars and organic acids were recorded. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of enzymes responsible for the metabolism of sugars and acids were quantified and expressions of related genes were determined using quantitative real-time PCR. The results revealed that 0.2% borax was a promising treatment among other B applications for the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, , , , , , , , , and may play an important role in soluble sugars metabolism in fruit pulp of loquat. Similarly, , , , , , , and may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.
可溶性糖和有机酸是成熟果实中含量最丰富的成分，它们在果实风味和口感的形成中起着关键作用。一些枇杷品种酸含量高，严重影响果实品质，降低商品价值。因此，研究枇杷糖酸代谢的生理机制可以阐明其在果实中的形成、积累和降解机制。据报道，施用矿质元素是改善果实糖酸平衡的一种有效方法。在本研究中，对枇杷树进行了0.1%、0.2%和0.3%硼砂的叶面喷施，并记录了可溶性糖和有机酸的变化。分别采用高效液相色谱示差折光检测器（HPLC-RID）和超高效液相色谱-质谱联用仪（UPLC-MS）测定可溶性糖和有机酸的含量。对负责糖和酸代谢的酶活性进行了定量分析，并采用实时荧光定量PCR技术测定了相关基因的表达。结果表明，在其他硼处理中，0.2%硼砂处理可提高枇杷果实的可溶性糖含量，降低酸含量。相关性分析表明，蔗糖磷酸合成酶（SPS）、蔗糖合成酶（SS）、果糖激酶（FK）和己糖激酶（HK）可能参与了枇杷果肉中果糖和葡萄糖代谢的调控。而苹果酸含量与NADP-苹果酸酶（NADP-ME）活性呈负相关，与NAD-苹果酸脱氢酶（NAD-MDH）活性呈正相关。同时，[此处原文缺失部分基因名称]可能在枇杷果肉可溶性糖代谢中起重要作用。同样，[此处原文缺失部分基因名称]可能对枇杷果实苹果酸的生物合成有重要贡献。本研究为今后阐明枇杷可溶性糖和苹果酸生物合成调控的关键机制提供了新的见解。
