Laboratory of Plant Physiology, Department Biology, Golestan University, Gorgan, Iran.
Laboratory of Plant Physiology, Department Biology, Golestan University, Gorgan, Iran.
Plant Sci. 2023 Oct;335:111823. doi: 10.1016/j.plantsci.2023.111823. Epub 2023 Aug 10.
Biological nitrogen-fixation is important in increasing crop efficiency. Azospirillum is a nitrogen-fixing microorganism that naturally coexists with grasses roots. The present study was undertaken to clarify the role of rice root cell walls in the acceptance of two Azospirillum species, alone or in combination with indole-3-acetic acid (IAA) and gibberellic acid (GA) treatments. Rice seedlings were grown in Yoshida solution for 21 days and then inoculated with A. brasilense and A. irakens in the presence of 0, 0.57, and 1.14 mM of IAA or 0, 0.29, and 0.58 mM GA or a combination of 1.14 mM of IAA and 0.58 mM of GA. The results showed that the amount of hydrogen peroxide, lipid peroxidation, total nitrogen and activity of ferulic acid peroxidase, NADPH oxidase, nitrate reductase, pectin methyl esterase, cellulase, mannanase, xylanase and pectinase were significantly increased in inoculated samples treated with or without phytohormones. The highest activity of these enzymes was observed in A. brasilense- inoculated rice roots in auxin+gibberellin treatment. In the latter, the activity of phenylalanine ammonia lyase and wall ferulic acid peroxidase enzymes, the content of cell wall polysaccharide, lignin, and total phenolic compounds were the least, compared to controls and also with those samples which were inoculated with A. irakens. The results indicate an active role of the wall and its enzymes in allowing bacteria to enter the roots. Understanding this mechanism can improve the methods of inoculating bacteria into plants and increase crop efficiency, which will result in reduced use of chemical fertilizers and their destructive environmental effects.
生物固氮在提高作物效率方面很重要。固氮微生物 Azospirillum 与草类根系自然共存。本研究旨在阐明水稻根细胞壁在接受两种固氮微生物（单独或与吲哚-3-乙酸（IAA）和赤霉素（GA）处理相结合）时的作用。将水稻幼苗在 Yoshida 溶液中培养 21 天，然后用 A. brasilense 和 A. irakens 接种，同时添加 0、0.57 和 1.14 mM 的 IAA 或 0、0.29 和 0.58 mM 的 GA 或 1.14 mM 的 IAA 和 0.58 mM 的 GA 的组合。结果表明，在接种样品中，添加或不添加植物激素处理后，过氧化氢、脂质过氧化、总氮以及阿魏酸过氧化物酶、NADPH 氧化酶、硝酸还原酶、果胶甲酯酶、纤维素酶、甘露聚糖酶、木聚糖酶和果胶酶的活性均显著增加。这些酶的活性在添加生长素+赤霉素的 A. brasilense 接种水稻根中最高。在后一种情况下，与对照相比，苯丙氨酸解氨酶和细胞壁阿魏酸过氧化物酶的活性以及细胞壁多糖、木质素和总酚类化合物的含量均最低，与接种 A. irakens 的样品也最低。结果表明，细胞壁及其酶在允许细菌进入根部方面发挥了积极作用。了解这种机制可以改进将细菌接种到植物中的方法，提高作物效率，从而减少化肥的使用及其对环境的破坏性影响。
