摘要:土壤盐渍化已经成为全球重要的生态环境问题之一, 农业生态系统中土壤盐分增加会影响作物生长发育、导致减产。近年来, 随着微生物组学研究的深入, 微生物提升植物抗逆性功能认识的加深, 生物肥料开始应用于盐碱地植物修复中。为探究根际促生菌在高盐环境中对小麦生长及代谢的影响, 本文选取一株分离自盐地碱蓬根际土中、具有耐盐和分泌植物生长素功能的克锡勒氏细菌(Kushneria indalinina JP-JH), 选取耐盐小麦品种‘小偃60’, 在无盐(0 mmol·L?1)、低盐(200 mmol·L?1)和高盐(400 mmol·L?1)的水培条件下接种耐盐促生菌JP-JH, 分析其对小麦苗期生长及根系分泌有机酸的影响。培养40 d后, 在无盐、低盐、高盐条件下, 接种JP-JH组小麦幼苗鲜重显著高于未接种对照组(P<0.05); 在无盐、低盐时, 接菌组的小麦幼苗干重显著高于对照组(P<0.05); 且在高盐胁迫时, 接菌组株高显著高于对照处理(P<0.05)。在无盐条件下, 接菌未对小麦幼苗根系分泌的6种有机酸产生显著影响; 在盐胁迫(低盐以及高盐)条件下, 接菌显著提高了根系分泌草酸和酒石酸含量(P<0.05)。上述结果表明耐盐促生菌能够在苗期促进小麦的生长发育, 且对根系分泌的部分有机酸产生了显著影响, 草酸和酒石酸可能在微生物-植物互作中具有重要作用。本研究揭示了细菌K. indalinina JP-JH对小麦的耐盐促生效应以及对根系分泌有机酸的影响, 为开发具有提升小麦耐盐促生功能的生物肥料提供理论依据和菌种资源。
关键词:耐盐促生菌/
克锡勒氏菌/
小麦/
根系分泌物/
有机酸
Abstract:Globally, soil salinization is a major land degradation process, taking more than 1 million hectares of farmland out of production per year, threatening food security. In salt-affected soils, crop growth, development, and yield dramatically decrease due to salt toxicity in plants, reduced soil fertility and water availability to plants, and altered hydraulic properties of the soil. The rhizospheric microbiome is closely related to crop stress tolerance. Plants recruit specific groups of microbes in the rhizosphere, which provide nutrients and plant hormones that promote plant growth and stress tolerance. Kushneria indalinina JP-JH is a salt-tolerant and auxin-secreting bacteria strain isolated from the rhizosphere of Suaeda salsa. In this study, the effects of K. indalinina JP-JH on the growth and salt tolerance of wheat seedlings were investigated. The experiment was conducted using the wheat variety ‘Xiaoyan 60’ in a hydroponic system with Hoagland nutrient solution. The seedlings were inoculated with K. indalinina JP-JH under no salt (0 mmol?L?1), low salt (200 mmol?L?1), and high salt (400 mmol?L?1) conditions. Seeds without bacterial inoculation were prepared under the same conditions and used as control treatments. Plant growth parameters and organic acids contents in the root exudates were analyzed after 40 days of incubation. The results showed that the fresh weight of wheat seedlings in the treatments with K. indalinina JP-JH inoculation was significantly higher than that of the uninoculated group at all three salt concentrations. K. indalinina JP-JH inoculation significantly increased the plant dry weight of the whole plant under both salt-free and low salt-stressed conditions but had no significant effect on dry weight under high salt-stressed conditions. Meanwhile, K. indalinina JP-JH inoculation significantly increased plant height under high salt-stressed conditions but had no significant effect under salt-free and low salt-stressed conditions. Dry weight and plant height were negatively related to the salt concentration in the inoculated and uninoculated treatments. The concentrations of six organic acids (oxalic acid, tartaric acid, malic acid, citric acid, fumaric acid, and succinic acid) secreted from roots were determined for treatments with different salt concentrations, with or without bacterial inoculation. K. indalinina JP-JH inoculation significantly increased the contents of oxalic acid and tartaric acid in the root exudates under salt-stressed conditions (both low and high salt concentrations) but had no significant effect on organic acids secretion under salt-free conditions. This suggests that oxalic acid and tartaric acid may play important roles in regulating plant-microbe interactions and improving the salt tolerance of wheat variety ‘Xiaoyan 60’. Taken together, our results indicate that K. indalinina JP-JH promotes plant growth and development and improves the salt tolerance of wheat at seedling stage, which may be related to alterations in the root exudation potential and plant-microbe interactions. This study produced new experimental data on the mechanisms of microorganisms that promote plant growth and salt tolerance and provided biological resources for developing biofertilizers to enhance wheat growth under salt stress conditions.
Key words:Salt-tolerant and growth-promoting bacteria/
Kushneria indalinina/
Wheat/
Root exudates/
Organic acid
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