Abstract
As the main economic crop cultivated in the Yellow River Delta, winter jujube contains various nutrients. However, soil salinization and fungal diseases have affected the yield and quality of winter jujube. In order to use plant growth-promoting rhizobacteria (PGPR) to reduce these damages, the antagonistic bacteria CZ-6 isolated from the rhizosphere of wheat in saline soil was selected for experiment. Gene sequencing analysis identified CZ-6 as Bacillus amyloliquefaciens. In order to understand the salt tolerant and disease-resistant effects of CZ-6 strain, determination of related indicators of salt tolerance, pathogen antagonistic tests, and anti-fungal mechanism analyses was carried out. A pot experiment was conducted to evaluate the effect of CZ-6 inoculation on the rhizosphere microbial community of winter jujube. The salt tolerance test showed that CZ-6 strain can survive in a medium with a NaCl concentration of 10% and produces indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Studies on the inhibition mechanism of pathogenic fungi show that CZ-6 can secrete cellulase, protease, and xylanase. Gas chromatography-mass spectrometry (GC-MS) analysis showed that CZ-6 can release volatile organic compounds (VOCs), including 2-heptanone and 2-nonanone. In addition, the strain can colonize the rhizosphere and migrate to the roots, stems, and leaves of winter jujube, which is essential for plant growth or defense against pathogens. Illumina MiSeq sequencing data indicated that, compared to the control, the abundance of salt-tolerant bacteria Tausonia in the CZ-6 strain treatment group was significantly increased, while the richness of Chaetomium and Gibberella pathogens was significantly reduced. Our research shows that CZ-6 has the potential as a biological control agent in saline soil. Plant damage and economic losses caused by pathogenic fungi and salt stress are expected to be alleviated by the addition of salt-tolerant antagonistic bacteria.
Highlights
Located in the northern part of the Shandong Province, the Yellow River Delta is a newly developed salinization system in China
The screening results show that CZ-6 has antagonistic effects against Colletotrichum gloeosporioides, Fusarium oxysporum, Bipolaris sorokiniana, and Botryosphaeria dothidea (Figure 1)
Homology analysis of the gyrB sequence revealed that the similarity coefficient between the CZ-6 strain and B. amyloliquefaciens was 99% (Figure 2)
Summary
Located in the northern part of the Shandong Province, the Yellow River Delta is a newly developed salinization system in China. The salinization of the soil in this area is prominent with a fragile ecological environment, which severely restricts agricultural activities in that region [1]. “Dongzao”) is the main economic crop cultivated in the Yellow River Delta [2]. Winter jujube was exposed to salt stress and fungal diseases at the same time. Soil salinization affects the occurrence and spread of pathogens, increasing the invasiveness of plant pathogenic fungi [3]. Common jujube fungal diseases include gray mold, stem rot, and anthracnose, which are usually caused by Botrytis cinerea, Botryosphaeria dothidea, and Colletotrichum gloeosporioides, respectively [4].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
