PJB-2015-76
ACCUMULATION OF CHOLINE AND GLYCINEBETAINE AND DROUGHT STRESS TOLERANCE INDUCED IN MAIZE (ZEA MAYS) BY THREE PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) STRAINS
WEI GOU1, LI TIAN1, ZHI RUAN, PENG ZHENG1, FUCAI CHEN1, LING ZHANG, ZHIYAN CUI1, PUFAN ZHENG, ZHENG LI, MEI GAO1, WEI SHI1, LIXIN ZHANG1*, JIANCHAO LIU1 AND JINGJIANG HU1
Abstract
The role of plant growth promoting rhizobacteria (PGPR) in inducing the tolerance of crop plants to drought is vital in regulation of physiological reactions that eventually adapts to a stressed environment, however, how PGPR strain induces better drought resistance by accumulation of choline and glycinebetaine (GB) in maize under drought stress (DS) is still poorly understood. A pot experiment was carried out to evaluate the induced role in maize by the three PGPR strains i.e. Klebsiella variicola F2 (KJ465989), Raoultella planticola YL2 (KJ465991) and Pseudomonas fluorescens YX2 (KJ465990) in view of plant growth, water relations and accumulation of choline and GB in leaves. Seedlings of cultivar Zhengdan 958 were inoculated with strains F2, YL2 and YX2 under different DS degrees induced by different PEG-6000 concentrations of 0, 10%, 15% and 20%. The soil microbe strains F2, YL2 and YX2 substantially enhanced the accumulation of choline and GB, and in turn improved leaf relative water content (RWC) and dry mater weight (DMW) under varying DS regimes. The best responses induced by PGPR were obtained by strain YX2 regardless of DS degree and all three strains under moderate DS stimulated by 10-15% concentrations of PEG-6000. The PGPR strains were involved in the regulation of osmotic adjustment via accumulations of choline and subsequent GB, resulting in improvement of water relations and plant growth in maize plants under DS. The effects of PGPR strains on improvement of plant drought resistance might be dependent on microbial species and degree of DS.
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