Zhang Lei, Dong Danhui, Wang Jinfang, Wang Zhirong, Zhang Jiaojiao, Bai Ru-Yue, Wang Xuewei, Rubio Wilhelmi Maria Del Mar, Blumwald Eduardo, Zhang Na, Guo Yang-Dong
College of Horticulture, China Agricultural University, Beijing, 100193, China.
Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
New Phytol. 2022 Oct;236(1):165-181. doi: 10.1111/nph.18336. Epub 2022 Jul 16.
In acidic soils, aluminum (Al) toxicity is the main factor inhibiting plant root development and reducing crops yield. STOP1 (SENSITIVE TO PROTON RHIZOTOXICITY 1) was a critical factor in detoxifying Al stress. Under Al stress, STOP1 expression was not induced, although STOP1 protein accumulated, even in the presence of RAE1 (STOP1 DEGRADATION E3-LIGASE). How the Al stress triggers and stabilises the accumulation of STOP1 is still unknown. Here, we characterised SlSTOP1-interacting zinc finger protein (SlSZP1) using a yeast-two-hybrid screening, and generated slstop1, slszp1 and slstop1/slszp1 knockout mutants using clustered regularly interspaced short palindromic repeats (CRISPR) in tomato. SlSZP1 is induced by Al stress but it is not regulated by SlSTOP1. The slstop1, slszp1 and slstop1/slszp1 knockout mutants exhibited hypersensitivity to Al stress. The expression of SlSTOP1-targeted genes, such as SlRAE1 and SlASR2 (ALUMINUM SENSITIVE), was inhibited in both slstop1 and slszp1 mutants, but not directly regulated by SlSZP1. Furthermore, the degradation of SlSTOP1 by SlRAE1 was prevented by SlSZP1. Al stress increased the accumulation of SlSTOP1 in wild-type (WT) but not in slszp1 mutants. The overexpression of either SlSTOP1 or SlSZP1 did not enhance plant Al resistance. Altogether, our results show that SlSZP1 is an important factor for protecting SlSTOP1 from SlRAE1-mediated degradation.
在酸性土壤中，铝（Al）毒性是抑制植物根系发育和降低作物产量的主要因素。STOP1（对质子根毒性敏感1）是解除铝胁迫的关键因素。在铝胁迫下，尽管STOP1蛋白积累，但即使存在RAE1（STOP1降解E3连接酶），STOP1的表达也不会被诱导。铝胁迫如何触发并稳定STOP1的积累仍然未知。在这里，我们通过酵母双杂交筛选鉴定了与SlSTOP1相互作用的锌指蛋白（SlSZP1），并利用番茄中的成簇规律间隔短回文重复序列（CRISPR）生成了slstop1、slszp1和slstop1/slszp1敲除突变体。SlSZP1受铝胁迫诱导，但不受SlSTOP1调控。slstop1、slszp1和slstop1/slszp1敲除突变体对铝胁迫表现出超敏感性。SlSTOP1靶向基因，如SlRAE1和SlASR2（铝敏感）的表达在slstop1和slszp1突变体中均受到抑制，但不受SlSZP1直接调控。此外，SlSZP1阻止了SlRAE1对SlSTOP1的降解。铝胁迫增加了野生型（WT）中SlSTOP1的积累，但在slszp1突变体中没有增加。SlSTOP1或SlSZP1的过表达均未增强植物对铝的抗性。总之，我们的结果表明，SlSZP1是保护SlSTOP1免受SlRAE1介导降解的重要因素。
