Colonization and Maize Growth Promotion Induced by Phosphate Solubilizing Bacterial Isolates

Abstract

Phosphorus (P) limits the production of maize, one of the major food crops in China. Phosphate-solubilizing bacteria (PSB) have the capacity to solubilize phosphate complexes into plant absorbable and utilizable forms by the process of acidification, chelation, and exchange reactions. In this study, six bacteria, including one Paenibacillus sp. B1 strain, four Pseudomonas sp. strains (B10, B14, SX1, and SX2) and one Sphingobium sp. SX14 strain, were those isolated from the maize rhizosphere and identified based on their 16S rRNA sequences. All strains could solubilize inorganic P (Ca3(PO4)2, FePO4 and AlPO4), and only B1 and B10 organic P (lecithin). All strains, except of SX1, produced IAA, and SX14 and B1 showed the highest level. B1 incited the highest increase in root length and the second increase in shoot and total dry weight, shoot length, and total P and nitrogen (N), along with increased root length. In addition, by confocal laser scanning microscopy (CLSM), we found that green fluorescent protein (GFP)-labeled B1 mainly colonized root surfaces and in epidermal and cortical tissue. Importantly, B1 can survive through forming spores under adverse conditions and prolong quality guarantee period of bio-fertilizer. Therefore, it can act as a good substitute for bio-fertilizer to promote agricultural sustainability.

Phosphate solubilizing bacteria stimulate wheat rhizosphere and endosphere biological nitrogen fixation by improving phosphorus content

“…The ability of PGPR strains B1 and BJ-18 to form close associations with plant roots, as established with observation of GFP-tagged constructs (Li et al, 2017(Li et al, , 2019a, could explain the synergy reported herein. Endophytes interact closely with plant hosts and readily exert beneficial traits (Santoyo et al, 2016).…”

“…Paenibacillus sp. B1 (accession number: KY111475), isolated from the maize rhizosphere, is a novel species with P solubilizing ability and produce IAA (Li et al, 2017). P. beijingensis BJ-18 and Paenibacillus sp.…”

“…Obervations of GFP-labbled Paenibacillus sp. B1 shows that this P-solubilizing strain effectively colonizes maize root surface and in epidermal and cortical tissues (Li et al, 2017).…”

Paenibacillusstrains with nitrogen fixation and multiple beneficial properties for promoting plant growth

“…The tested strains were evaluated for their potential to promote plant growth on wheat cultivar Jimai 22 (Shandong Runfeng Seed Industry Co., Ltd., Shandong Sheng, China), cucumber Zhongnong 8 (Beijing Shengfeng Garden Agricultural Technology Co., Ltd., Beijing, China) and tomato Jiafen 15 (Tianjin Xingke Seed Co., Ltd., Tianjin, China) seedlings in the greenhouse of China Agricultural University, Beijing, China. The lengths and dry weights of three plants inoculated with strains were determined by the procedure described by Li et al (2017).…”

“…Given these advantages, PGPR are widely used in sustainable agriculture to promote plant growth and control fungal pathogens (Verma et al, 2018). Some of Paenibacillus species can influence plant growth by one or more of mechanisms mentioned above (Li et al, 2017; Weselowski et al, 2016; Xie et al, 2016). Nowadays, with the rapid growth of population, most regions have increased the cereals production by the overuse of fertilizers, which not only accounts for a larger percentage of farmers’ expenses but also increase risks of negative effect on environment (Curatti & Rubio, 2014; Ivleva et al, 2016; Tayefeh et al, 2018).…”