Amino acid transporters play important roles in plant growth and stress tolerance; however, whether the abscisic acid signaling pathway regulates their transcription in rice (Oryza sativa) under salt stress remains unclear. In this study, we report that the transcription factor OsMYB2 (MYB transcription factor 2) of the abscisic acid signaling pathway mediates the expression of the gene encoding the amino acid transporter OsANT1 (aromatic and neutral amino acid transporter 1), which positively regulates growth and salt tolerance in rice. OsANT1 was mainly expressed in the leaf blade and panicle under normal conditions and transports leucine, phenylalanine, tyrosine and proline, positively regulating tillering and yield in rice. Nevertheless, salt stress induced the accumulation of abscisic acid and strongly increased the expression level of OsANT1 in the root, resulting in enhanced salt tolerance of rice seedlings, as evidenced by higher proline concentration and antioxidant-like enzyme activities and lower malondialdehyde and hydrogen peroxide concentrations. Moreover, we showed that OsMYB2 interacts with the promoter of OsANT1 and promotes its expression. Overexpression of OsMYB2 also improved tillering, yield, and salt tolerance in rice. In conclusion, our results suggest that the transcription factor OsMYB2 triggers OsANT1 expression and regulates growth and salt tolerance in rice, providing insights into the role of the abscisic acid signaling pathway in the regulatory mechanism of amino acid transporters in response to salt stress.

中文翻译：

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转录因子 OsMYB2 触发氨基酸转运蛋白 OsANT1 表达以调节水稻生长和耐盐性


氨基酸转运蛋白在植物生长和抗逆性中起重要作用;然而，脱落酸信号通路是否调节它们在盐胁迫下水稻 （Oryza sativa） 中的转录仍不清楚。在这项研究中，我们报道了脱落酸信号通路的转录因子 OsMYB2 （MYB 转录因子 2） 介导编码氨基酸转运蛋白 OsANT1 （芳香族和中性氨基酸转运蛋白 1） 的基因的表达，该基因正向调节水稻的生长和耐盐性。OsANT1 在正常条件下主要在叶片和穗中表达，转运亮氨酸、苯丙氨酸、酪氨酸和脯氨酸，正向调节水稻分蘖和产量。然而，盐胁迫诱导了脱落酸的积累，并强烈增加了根系中 OsANT1 的表达水平，导致水稻幼苗的耐盐性增强，这表现为较高的脯氨酸浓度和类抗氧化酶活性以及较低的丙二醛和过氧化氢浓度。此外，我们发现 OsMYB2 与 OsANT1 的启动子相互作用并促进其表达。过表达 OsMYB2 还改善了水稻的分蘖、产量和耐盐性。总之，我们的结果表明，转录因子 OsMYB2 触发水稻 OsANT1 表达并调节生长和耐盐性，为脱落酸信号通路在氨基酸转运蛋白响应盐胁迫的调节机制中的作用提供了见解。