干旱沙地白刺根际Bacillus halotolerans DGL6对“青麦7号”的促生及防病效果

Bacillus halotolerans DGL6 from the rhizosphere of Nitraria tangutorum in arid sandy land promotes growth and controls diseases of Triticum aestivum ‘Qingmai 7’

摘要:

【背景】青海高原特殊生境孕育着特殊适生性的微生物资源。【目的】探究适生于高原生境的芽孢杆菌对高寒牧草的促生防病效应。【方法】以分离自青海海西州大格勒干旱沙地白刺(Nitraria tangutorum)根围的Bacillus halotolerans DGL6为研究材料，测定其对“青麦7号”的促生防病效应。分别以浸种、灌根的方法测定其对“青麦7号”种子萌发及幼苗生长的效应，并测定12 d内幼苗生理指标的变化；测定菌株DGL6抑制“青麦7号”幼苗离体叶片感染病原真菌活性；以平板对峙法测定其对病原真菌的抑制率；以透明圈法检测其产抑菌相关水解酶活性。【结果】菌株DGL6对“青麦7号”种子萌发及幼苗生长具有显著的促生效果，种子萌发的芽长、根长及鲜重分别提高27.26%、23.03%和45.42%，12 d内幼苗的株高、根长、鲜重分别显著提高33.42%、107.85%和95.24%，叶绿素、可溶性糖及可溶性蛋白含量显著增加，丙二醛含量下降；喷施DGL6菌悬液可明显抑制小麦赤霉菌在“青麦7号”离体叶片上的生长；菌株DGL6对小麦赤霉菌(Fusarium graminearum)表现出显著拮抗活性(抑菌圈平均直径为18 mm)；菌株DGL6在4种水解酶检测培养基上均形成明显透明圈，表明其具有分泌纤维素酶、果胶酶、蛋白酶和b-1,3-葡聚糖酶的能力。【结论】本研究为促进高原作物“青麦7号”的生长、提高其抗病性提供了优异菌株及理论依据。

Abstract:

[Background] The extreme eco-environment of Qinghai Plateau harbors unique microbial resources. [Objective] To explore the growth-promoting and disease-controlling effects of Bacillus adaptive to the alpine environment on the herbage. [Methods] The growth-promoting and disease-controlling effects of Bacillus halotolerans DGL6 isolated from the rhizosphere of Nitraria tangutorum in Haixi prefecture of Qinghai province on the germination and seedling growth of Triticum aestivum ‘Qingmai 7’ were determined by seed soaking and root irrigation methods, respectively. The changes in physiological indexes of the seedlings within 12 days were measured. The inhibitory activity of strain DGL6 on fungal infection was measured with the detached leaves of ‘Qingmai 7’ seedlings. The inhibition rate and hydrolase activity of strain DGL6 against pathogenic fungi were determined by plate confrontation method and inhibition zone method, respectively. [Results] Strain DGL6 had significant effect on the seed germination and seedling growth of ‘Qingmai 7’. It increased the sprout length, root length, and fresh weight of ‘Qingmai 7’ by 27.26%, 23.03%, and 45.42%, respectively. Furthermore, it increased the plant height, root length, and fresh weight of seedlings within 12 days by 33.42%, 107.85%, and 95.24%, respectively. The strain significantly increased the content of chlorophyll, soluble sugar, and soluble protein and decreased the content of malondialdehyde. Spraying DGL6 suspension significantly inhibited the growth of Fusarium graminearum on the detached leaves of ‘Qingmai 7’. DGL6 showed significant antagonistic activity to F. graminearum, with the mean inhibition zone diameter of 18 mm. DGL6 formed distinct inhibition zones in the media for detection of four hydrolases, demonstrating the ability to secrete cellulase, pectinase, protease, and b-1,3-glucanase. [Conclusion] This study provided an elite strain and a theoretical basis for promoting the growth and improving the disease resistance of the plateau crop ‘Qingmai 7’.