Salicylic acid (SA) is the phytohormone responsible for the regulation of growth and response to environmental stress in plants. In the present study, the application of 1 μM SA significantly enhanced the SA content in rice roots and improved their growth when affected by Al toxicity by concomitantly decreasing the Al content of the root apex. The addition of SA significantly inhibited the synthesis of pectin and hemicellulose, suppressed the activity of pectin methylesterase (PME), and decreased the cell wall Al content. The expression of OsSTAR1 (sensitive to Al rhizotoxicity) and OsSTAR2 was induced by SA to mask the Al-binding sites in the cell walls. The expression of OsALS1 (Al sensitive) was also stimulated by SA, which improved the transport of cytoplasmic Al into the vacuoles. In rice affected by Al toxicity, SA significantly increased the activity of catalase and peroxidase and reduced the H 2 O 2 content and malondialdehyde content. The expression of OsACS1 (ACC synthase) and OsACO1 (ACC oxidase) was inhibited by SA and thus inhibited ethylene emission. The addition of ethylene precursor 1-aminocylopropane-1-carboxylic acid (ACC) along with SA under Al toxicity conditions aggravated the inhibition of root elongation, accompanied by an increased Al content in the root apex and cell walls, increased pectin content, and rendered PME activity greater than with single Al treatment. However, the addition of aminoethoxyvinylglycine (AVG, inhibitor of the ACC synthase) along with SA under Al toxicity conditions showed the opposite effect, indicating that SA inhibited ethylene emission, thus reducing the Al deposition on cell walls.

中文翻译：

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水杨酸在铝毒条件下通过抑制乙烯释放减轻水稻根系伸长抑制的作用

水杨酸 (SA) 是一种植物激素，负责调节植物的生长和对环境胁迫的反应。在本研究中，当受到铝毒性影响时，1 μM SA 的施用显着提高了水稻根中的 SA 含量，并通过同时降低根尖的铝含量来促进其生长。SA的加入显着抑制果胶和半纤维素的合成，抑制果胶甲酯酶（PME）的活性，降低细胞壁Al含量。OsSTAR1（对铝根毒性敏感）和 OsSTAR2 的表达由 SA 诱导以掩盖细胞壁中的铝结合位点。OsALS1（铝敏感）的表达也受到 SA 的刺激，这改善了细胞质铝进入液泡的运输。在受铝中毒影响的水稻中，SA显着提高过氧化氢酶和过氧化物酶的活性，降低H 2 O 2 含量和丙二醛含量。OsACS1（ACC合酶）和OsACO1（ACC氧化酶）的表达被SA抑制，从而抑制乙烯的排放。在铝毒性条件下，乙烯前体 1-氨基环丙烷-1-羧酸 (ACC) 和 SA 的加入加剧了根伸长的抑制，伴随着根尖和细胞壁中铝含量的增加，果胶含量的增加，并导致PME 活性大于单一铝处理。然而，在铝毒性条件下，氨基乙氧基乙烯基甘氨酸（AVG，ACC 合酶抑制剂）与 SA 的添加显示出相反的效果，表明 SA 抑制了乙烯的排放，从而减少了铝在细胞壁上的沉积。