State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Beijing Academy of Forestry and Pomology Sciences, Beijing Engineering Research Center for Deciduous Fruit Trees, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Ministry of Agriculture and Rural Affairs, Beijing, 100093, People's Republic of China.
BMC Plant Biol. 2021 Jan 19;21(1):52. doi: 10.1186/s12870-021-02831-y.
Soil salinity is a critical threat to global agriculture. In plants, the accumulation of xanthine activates xanthine dehydrogenase (XDH), which catalyses the oxidation/conversion of xanthine to uric acid to remove excess reactive oxygen species (ROS). The nucleobase-ascorbate transporter (NAT) family is also known as the nucleobase-cation symporter (NCS) or AzgA-like family. NAT is known to transport xanthine and uric acid in plants. The expression of MdNAT is influenced by salinity stress in apple.
In this study, we discovered that exogenous application of xanthine and uric acid enhanced the resistance of apple plants to salinity stress. In addition, MdNAT7 overexpression transgenic apple plants showed enhanced xanthine and uric acid concentrations and improved tolerance to salinity stress compared with nontransgenic plants, while opposite phenotypes were observed for MdNAT7 RNAi plants. These differences were probably due to the enhancement or impairment of ROS scavenging and ion homeostasis abilities.
Our results demonstrate that xanthine and uric acid have potential uses in salt stress alleviation, and MdNAT7 can be utilized as a candidate gene to engineer resistance to salt stress in plants.
土壤盐度是全球农业的一个关键威胁。在植物中，黄嘌呤的积累会激活黄嘌呤脱氢酶（XDH），XDH 催化黄嘌呤氧化/转化为尿酸，以去除过量的活性氧（ROS）。核苷碱基-抗坏血酸转运蛋白（NAT）家族也被称为核苷碱基-阳离子协同转运蛋白（NCS）或 AzgA 样家族。NAT 已知在植物中转运黄嘌呤和尿酸。苹果中 MdNAT 的表达受盐胁迫影响。
在本研究中，我们发现外源施用黄嘌呤和尿酸可增强苹果植株对盐胁迫的抗性。此外，与非转基因植株相比，MdNAT7 过表达转基因苹果植株表现出更高的黄嘌呤和尿酸浓度，以及对盐胁迫的耐受性增强，而 MdNAT7 RNAi 植株则表现出相反的表型。这些差异可能是由于 ROS 清除和离子稳态能力的增强或受损所致。
我们的结果表明，黄嘌呤和尿酸在缓解盐胁迫方面具有潜在的应用价值，MdNAT7 可以作为候选基因用于工程植物的耐盐性。
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