短小橘杆菌(Brevibacterium antarcticum) WN5代谢产物对烟苗的促生效应

Metabolites of Brevibacterium antarcticum strain WN5 promote the growth of tobacco seedlings

摘要:

【背景】短小橘杆菌(Brevibacterium antarcticum)菌株WN5筛选自贵州植烟土壤，具有氨转化能力，但其对烟草促生应用效果研究的报道较少。【目的】研究菌株WN5代谢产物对烟苗的促生作用。【方法】在烟苗十字期施用菌株WN5培养液，通过对烟苗外观农艺性状、根系形态结构及活性、氮素养分和抗逆性生理指标等数据的分析，探讨其促生效应。【结果】在菌株培养液中测定出了4种激素及激素合成前体：1-氨基环丙烷-1-羧酸、反式玉米素、吲哚-3-乙酸和水杨酸，将其施用在烟苗生长基质中，可促进地上部分生长，烟苗株高、茎围和鲜重分别增加42.74%、12.91%和5.00%，最大叶面积和叶片数也有增加趋势，但未达显著差异水平；烟苗叶绿素含量较对照增加32.86%；菌液处理根系的总面积、表面积、平均直径、平均长度、体积和根系活力分别显著增加35.42%、20.54%、18.22%、24.07%、36.56%和29.01%；对根系的促进作用大于地上部，根冠比显著提高41.67%。菌株WN5处理还提升了烟苗吸收养分的能力和抗逆能力，硝酸还原酶(nitrate reductase, NR)活性提升32.97%，过氧化氢酶(catalase, CAT)活性、超氧化物歧化酶(superoxide dismutase, SOD)活性和可溶性蛋白(soluble protein, SP)增加了36.31%、16.23%和18.50%。【结论】菌株WN5通过产生植物激素显著促进烟苗地上部与根系的生长，提高根系活力，增强对氮素的吸收能力和烟苗的抗氧化应激能力，具有广泛的应用潜力。

关键词:烟苗;代谢产物;促生菌;促生效果

Abstract:

[Background] The Brevibacterium antarcticum strain WN5, isolated from tobacco- cultivating soil in Guizhou, possesses ammonia transformation capabilities. However, there are few reports on its efficacy in promoting tobacco growth. [Objective] To investigate the growth-promoting effect of WN5 metabolites on tobacco seedlings. [Methods] We applied the WN5 culture to the tobacco seedlings with two leaves and then determined the agronomic traits, morphological traits and vigor of roots, nitrogen nutrients, and stress resistance of the tobacco seedlings. [Results] Four plant hormones and hormone precursors: 1-aminocyclopropane-1-carboxylic acid, trans zeatin, indole-3-acetic acid, and salicylic acid, were detected in the strain culture. The strain culture was then applied to the matrix of tobacco seedlings, which promoted the shoot growth, increasing the plant height, stem circumference, and fresh weight of the seedlings by 42.74%, 12.91%, and 5.00%, respectively. However, the maximum leaf area and leaf number increased without statistically significance, The chlorophyll content in tobacco seedlings increased by 32.86% compared to the control. Additionally, the strain culture enhanced root growth and vigor, increasing the total area, surface area, average diameter, average length, volume, and vigor of roots by 35.42%, 20.54%, 18.22%, 24.07%, 36.56%, and 29.01%, respectively. The growth-promoting effect of the strain culture was more significant on the roots than on the shoots, as the root-to-shoot ratio was increased by 41.67%. Moreover, the treatment with WN5 enhanced the nutrient absorption and stress resistance of tobacco seedlings. Specifically, the treatment increased the levels of nitrate reductase, catalase, superoxide dismutase, and soluble protein by 32.97%, 36.31%, 16.23%, and 18.50%, respectively. [Conclusion] B.antarcticum WN5 can promote the shoot and root growth, improve the root vigor, enhance the nitrogen absorption, and reduce the oxidative stress of tobacco seedlings by producing plant hormones. This finding suggests that WN5 has great potential for widespread application.

Key words:tobacco seedlings;metabolites;growth-promoting strain;growth-promoting effect