Seed soaking with Bacillus sp. strain HX-2 alleviates negative effects of drought stress on maize seedlings

Heqin Li1, Yanming Zhao1, and Xuwen Jiang1*
Drought, one of the most detrimental environmental factors for agricultural production all over the world, severely represses plant survival and productivity of crops. Microbial technology plays a prominent part in improving drought resistance of crops. Here, endophytic bacterium Bacillus megaterium strain HX-2 was isolated from healthy leaves of Agastache rugosa (Fisch. & C.A. Mey.) Kuntze; its drought tolerance level and growth promoting characteristics were carried out in vivo, and the effects of the bacterium on morphological, physiological and biochemical variables of maize (Zea mays L.) seedling under drought stress were investigated in a pot experiment. As a result, B. megaterium strain HX-2 had 15% tolerance to polyethylene glycol 6000, produced indoleacetic acid and dissolved phosphate. After inoculation with strain HX-2, plant height, root length, plant biomass, root:shoot ratio, root activity, leaf relative water content, proline content, plant P content, and enzyme activities including superoxide dismutase, catalase, peroxidase and ascorbate peroxidase increased considerably by 7.69%-42.9%, whereas electrolyte leakage and malondialdehyde content declined significantly by 28.17%-42.38% relative to drought stress. These changes suggested that strain HX-2 was able to alleviate negative effects of drought stress on plants by producing indoleacetic acid and dissolving phosphate to improve the antioxidant system of plants. This study will provide theoretical reference for cultivation of maize under drought stress.
Keywords: Antioxidant system, Bacillus megaterium, drought stress, indoleacetic acid production, phosphate solubilization property, Zea mays.
1Qingdao Agricultural University, College of Agronomy, No. 700 Changcheng Road, Chengyang District, Qingdao, Shandong 266109, China. *Corresponding author (mjxw888@163.com).