Isolation and screening of IAA-producing bacteria from glutinous sorghum leaves and its plant growth-promoting function

Subjects: Biology >> Botany >> Applied botany submitted time 2023-12-26 Cooperative journals: 《广西植物》

WANG Xinye ZHANG Min TIAN Xiaolong YUAN Ping LI Hongxia LUO Zhenbiao YUE Qianqian ZHAO Liang

Abstract： Glinous sorghum is an important raw material for the production of baijiu. During its growth process, glinous sorghum requires a substantial amount of chemical fertilizers. As an environmentally friendly fertilizer, microbial agent has great prospects in future. The aim of this paper is to develop a growth promoting microbial agent for glutinous sorghum. In this study, the glutinous sorghum leaves were used as experimental materials to isolate and screen microbial strains with plant growth hormone IAA (indole acetic acid) production ability. Phylogenetic analysis was performed to determine the taxonomic status of these microbial strains based on the 16S rDNA conserved sequences. The effects of the strains on glutinous sorghum seed germination was analyzed by soaking the seeds with bacterial suspension. The effect of strain on the sorghum seedlings growth was analyzed by pot experiment. The results were as follows: (1) Four microbial strains capable of producing IAA were isolated and screened from glutinous sorghum leaves, designated as HY1-1, HY1-2, HY1-3, and HY1-4. Among them, HY1-1 exhibited the highest IAA production per unit concentration which was 2.56 mol·L-1. (2) Bayesian inference tree analysis based on the 16S rDNA sequences revealed that all four strains belonged to Bacillus subtilis. (3) HY1-1, HY1-2, HY1-3, and HY1-4 could promote the glutinous sorghum seed germination rates. Compared to the control groups, the germination rates of glutinous sorghum seeds soaked in bacterial suspension significantly increased by 40.04% to 165.52%. Among them, HY1-1 demonstrated the most prominent promotion effect, with a germination rate increase of 165.52%. (4) HY1-1 strain was selected for a pot experiment. After 30 days of inoculation on the roots of glutinous sorghum seedlings, the stem heights of the seedlings significantly increased by 29.17%, and total phosphorus content increased significantly by 5.12%. The rhizosphere substrate of glutinous sorghum exhibited a significant increase in available nitrogen content by 31.70% and available phosphorus content by 28.88%. B. subtilis HY1-1, an endophytic bacterium in glutinous sorghum leaves, can promote the growth of glutinous sorghum plants by secreting the plant growth hormone IAA and providing necessary nutrients. This study provides genetic resources for the further development of microbial agents targeting the growth promotion of glutinous sorghum.

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