Promoting Effects and Mechanism of Bacillus velezensis WB on Watermelon (Citrullus lanatus) Plants
CHEN Zhong-Nan1,2,3, WANG Zhi-Gang1,2,3, XU Wei-Hui1,2,3,*
1 College of Life Science and Agroforestry, Qiqihar University, Qiqihar 161006, China; 2 Heilongjiang Provincial Technology Innovation Center of Agromicrobial Preparation Industrialization, Qiqihar 161006, China; 3 Heilongjiang Provincial Collaborative Innovation Center of Agrobiological Preparation Industrialization, Qiqihar 161006, China
Abstract Watermelon (Citrullus lanatus) is one of the most popular fruits. With people's continuous pursuit of quality of life, improving products quality has become a key factor in high sales of crops. Plant growth promoting rhizobacteria are a group of beneficial bacteria that promote plant uptake of nutrients from the soil and improve plant health. To investigate the growth promoting effect of Bacillus velezensis WB on watermelon plants. Strain WB and watermelon seeds were selected as materials, the growth promoting ability of strain WB was analyzed using functional culture medium, the growth promoting effect of strain WB was validated using seed germination experiments and pot experiments, and the growth promoting mechanism of strain WB was explored using RNA sequencing (RNA-seq). The results showed that B. velezensis WB had the ability to produce auxin (IAA) and cellulase, as well as the ability to solubilize phosphorus, potassium, and to fixate nitrogen. The results of seed germination and pot experiments indicated that strain WB had a promoting effect on the growth of watermelon plants. In addition, strain WB upregulated the expression of genes related to plant growth promoting signaling pathways, including sesquiterpenoid and triterpenoid biosynthesis,phenylpropanoid biosynthesis, and plant hormone signal transduction pathway. Transcription factors were expressed in promoting growth, such as myoptosis (MYB), NAC (NAM, ATAF and CUC), and Dof (DNA binding with one finger). In conclusion, this study found that B. velezensis WB could promote the growth of watermelon and elucidated its growth promoting mechanisms, and providing theoretical basis for its application in future.
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