School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.
Key Laboratory of Urban Agriculture, Ministry of Agriculture, Shanghai, 201101, China.
Plant J. 2022 Nov;112(3):756-771. doi: 10.1111/tpj.15977. Epub 2022 Sep 23.
Aluminum (Al) toxicity severely restricts plant growth in acidic soils (pH < 5.0). In this study, an R2R3-MYB transcription factor (TF) gene, MsMYB741, was cloned from alfalfa. Its function and gene regulatory pathways were studied via overexpression and RNA interference of MsMYB741 in alfalfa seedlings. Results showed that root elongation increased as a result of MsMYB741 overexpression (MsMYB741-OE) and decreased with MsMYB741 RNA interference (MsMYB741-RNAi) in alfalfa seedlings compared with the wild-type under Al stress. These were attributed to the reduced Al content in MsMYB741-OE lines, and increased Al content in MsMYB741-RNAi lines. MsMYB741 positively activated the expression of phenylalanine ammonia-lyase 1 (MsPAL1) and chalcone isomerase (MsCHI) by binding to MYB and ABRE elements in their promoters, respectively, which directly affected flavonoid accumulation in roots and secretion from root tips in plants under Al stress, eventually affecting Al accumulation in alfalfa. Additionally, MsABF2 TF directly activated the expression of MsMYB741 by binding to the ABRE element in its promoter. Taken together, our results indicate that MsMYB741 transcriptionally activates MsPAL1 and MsCHI expression to increase flavonoid accumulation in roots and secretion from root tips, leading to increased resistance of alfalfa to Al stress.
铝（Al）毒性严重限制了酸性土壤（pH<5.0）中植物的生长。在这项研究中，从紫花苜蓿中克隆了一个 R2R3-MYB 转录因子（TF）基因 MsMYB741。通过在紫花苜蓿幼苗中过表达和 RNA 干扰 MsMYB741 研究了其功能和基因调控途径。结果表明，与野生型相比，在 Al 胁迫下，MsMYB741 过表达（MsMYB741-OE）的苜蓿幼苗伸长，而 MsMYB741 RNA 干扰（MsMYB741-RNAi）的根伸长减少。这归因于 MsMYB741-OE 系中 Al 含量减少，而 MsMYB741-RNAi 系中 Al 含量增加。MsMYB741 通过结合其启动子中的 MYB 和 ABRE 元件分别正向激活苯丙氨酸解氨酶 1（MsPAL1）和查尔酮异构酶（MsCHI）的表达，直接影响 Al 胁迫下植物根系中的类黄酮积累和根尖分泌，最终影响紫花苜蓿中的 Al 积累。此外，MsABF2 TF 通过结合其启动子中的 ABRE 元件直接激活 MsMYB741 的表达。综上所述，我们的研究结果表明，MsMYB741 转录激活 MsPAL1 和 MsCHI 的表达，增加根系中的类黄酮积累和根尖分泌，从而提高苜蓿对 Al 胁迫的抗性。
