Preliminary Study on the Enhancement of Crop Drought Adaptation by Rhizosphere Microorganisms in Shangri-La Grape Region

PurposeTo evaluate the ability of rhizosphere microbes from Cabernet sauvignon grown in Shangri-La grape region to help plants resist drought stress, and to provide a theoretical basis for utilizing microorganisms to mitigate the deleterious impact of environmental stress on plants.

MethodsThe effects of extracts and filtrates (microorganisms removed) from C. sauvignon rhizosphere soil in four different regions of Shangri-La on tomato biomass were compared, scavenging reactive oxygen in tomato leaves under drought stress were determined. After isolation (LB plates), identification (16S rDNA) and screening of strains which showed strong antagonistic activity against Fusarium oxysporum in the rhizosphere soil of C. sauvignon in Bengzilan area, the effect of antagonistic bacterial suspensions on the growth of tomato seedlings under drought stress was further determined.

ResultsCompared with the filtrates, the soil extracts from four regions increased the biomass, the activity of catalase (CAT) and peroxidase (POD), and the content of proline (Pro), decreased the content of malondialdehyde (MDA) in tomato plants under drought stress. In addition, a total of 90 bacterial strains were isolated from the rhizosphere soil of C. sauvignon in Benzilan area, 12 of which showed strong antagonistic activity against F. oxysporum. Under drought, the whole plant, stem and leaf fresh weight of tomato seedlings increased after treated by most of the antagonistic bacterial suspensions, especially three strains from Bacillus (TR_56S44), Rhodococcus (T_123-S42) and Sphingomonas (4TZ16) showed significant effects respectively (P<0.05).

ConclusionRhizosphere soil extracts of C. sauvignon from four regions of Shangri-La could enhance tomato resistance to drought stress by increasing CAT and POD activities and Pro contents to remove intracellularly accumulated MDA. Among them, the antagonistic bacteria strains isolated and screened from the C. sauvignon rhizosphere soil in Benzilan promoted the growth of tomato seedlings and increased the fresh weight of plant stems, leaves and roots, which relieved the drought stress on plant growth.