Yan Dong, Gao Yu, Zhang Yumin, Li Dan, Dirk Lynnette M A, Downie A Bruce, Zhao Tianyong
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China.
J Exp Bot. 2024 Sep 27;75(18):5955-5970. doi: 10.1093/jxb/erae284.
Raffinose mitigates plant heat, drought, and cold stresses; however, whether raffinose contributes to plant waterlogging tolerance is unknown. The maize raffinose synthase mutant zmrafs-1 had seedlings that lack raffinose, generated fewer and shorter adventitious roots, and were more sensitive to waterlogging stress, while overexpression of the raffinose synthase gene, ZmRAFS, increased raffinose content, stimulated adventitious root formation, and enhanced waterlogging tolerance of maize seedlings. Transcriptome analysis of null segregant seedlings compared with zmrafs-1, particularly when waterlogged, revealed that the expression of genes related to galactose metabolism and the auxin biosynthetic pathway were up-regulated by raffinose. Additionally, indole-3-acetic acid content was significantly decreased in zmrafs-1 seedlings and increased in ZmRAFS-overexpressing seedlings. Inhibition of the hydrolysis of raffinose by 1-deoxygalactonojirimycin decreased the waterlogging tolerance of maize seedlings, the expression of genes encoding proteins related to auxin transport-related genes, and the indole-3-acetic acid level in the seedlings, indicating that the hydrolysis of raffinose is necessary for maize waterlogging tolerance. These data demonstrate that raffinose catabolism stimulates adventitious root formation via the auxin signaling pathway to enhance maize waterlogging tolerance.
棉子糖可减轻植物的热、干旱和冷胁迫；然而，棉子糖是否有助于植物耐涝尚不清楚。玉米棉子糖合酶突变体zmrafs-1的幼苗缺乏棉子糖，不定根生成数量少且短，对涝胁迫更敏感，而棉子糖合酶基因ZmRAFS的过表达增加了棉子糖含量，刺激不定根形成，并增强了玉米幼苗的耐涝性。与zmrafs-1相比，对纯合缺失分离幼苗进行转录组分析，特别是在涝胁迫条件下，结果显示棉子糖上调了与半乳糖代谢和生长素生物合成途径相关基因的表达。此外，zmrafs-1幼苗中吲哚-3-乙酸含量显著降低，而ZmRAFS过表达幼苗中吲哚-3-乙酸含量增加。1-脱氧半乳糖野尻霉素抑制棉子糖水解降低了玉米幼苗的耐涝性、与生长素转运相关基因编码蛋白的基因表达以及幼苗中的吲哚-3-乙酸水平，表明棉子糖水解对玉米耐涝性是必需的。这些数据表明，棉子糖分解代谢通过生长素信号通路刺激不定根形成，从而增强玉米的耐涝性。
