AUTHOR=Li Pu-Sheng , Kong Wei-Liang , Wu Xiao-Qin , Zhang Yu 

TITLE=Volatile Organic Compounds of the Plant Growth-Promoting Rhizobacteria JZ-GX1 Enhanced the Tolerance of Robinia pseudoacacia to Salt Stress

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.753332

DOI=10.3389/fpls.2021.753332

ISSN=1664-462X

ABSTRACT=Salt stress is one of the major abiotic stresses that affect plant growth and development. The use of plant growth-promoting rhizobacteria (PGPR) to mitigate salt stress damage in plants is an important way to promote crop growth under salt stress. Rahnella aquatilis JZ-GX1 is a PGPR strain, but it is not clear whether it can improve the salt tolerance of plants, and the role of volatile substances in plant salt tolerance is especially unknow. We investigated the effects of volatile organic compounds (VOCs) of JZ-GX1 on the growth performance, osmotic substances, ionic balance and antioxidant enzyme activities of acacia seedlings under 0 and 100 mM NaCl treatment and explored the VOCs associated with the JZ-GX1 strain. The results showed that compared to untreated seedlings, seedlings exposed to PGPR JZ-GX1 via direct contact with plant roots under salt stress exhibited increases in fresh weight, lateral root number and primary root length by approximately 255%, 100% and 71%, respectively. Robinia pseudoacacia seedlings exposed to VOCs of the JZ-GX1 strain showed increases in biomass, Soil and plant analyzer develotrnent（SPAD） and lateral root number by 132.1%, 101.6% and 166.7%, respectively, and decreases in malondialdehyde (MDA) content and increases in proline content and superoxide dismutase (SOD), peroxidase (POD) and glutathione reductase (GSH) activities were observed in acacia leaves. Importantly, the sodium-potassium ratios in roots, stems, and leaves of acacia exposed to VOCs of strain JZ-GX1 were significantly lower than those of the control, and this change in ion homeostasis was consistent with the upregulation of the (Na+, K+)/H+ reverse cotransporter RpNHX1 in plant roots. Through GC-MS and creatine chromatography, we also found that 2,3-butanediol in the volatile gas of strain JZ-GX1 was one of the important signaling substances for improving the salt tolerance of plants. The results showed that Rahnella aquatilis JZ-GX1 can promote the growth and yield of Robinia pseudoacacia under normal and salt stress conditions. The JZ-GX1 VOCs have good potential as protectants in improving the salt tolerance of plants, opening a window of opportunity for their application in salinized soils.