Isolation and molecular characterization of plant growth-promoting Bacillus spp. and their impact on sugarcane (Saccharum spp. hybrids) growth and tolerance towards drought stress

• Published in: Acta physiologiae plantarum Vol. 40; no. 11; pp. 1 - 15
• Main Authors: Chandra, Priyanka, Tripathi, Pramila, Chandra, Amaresh
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2018; Springer Nature B.V
• Subjects: Agriculture; Antioxidants; Bacillus megaterium; Bacillus subtilis; Biomedical and Life Sciences; Crop growth; Drought; Enzymatic activity; Enzyme activity; Enzymes; Exposure; Free radicals; Fructose; Gene expression; Gene sequencing; Hybrids; In vivo methods and tests; Invertase; Isoforms; Life Sciences; Nutrient content; Original Article; Plant Anatomy/Development; Plant Biochemistry; Plant Genetics and Genomics; Plant growth; Plant Pathology; Plant Physiology; Proline; Rhizosphere; rRNA 16S; Saccharum; Sucrose; Sugar; Sugarcane; Superoxide dismutase; Vigor; Weight; Plant growth-promoting rhizobacteria; Sugarcane; RT-PCR; Antioxidant enzyme system; qRT-PCR
• ISSN: 0137-5881; 1861-1664
• DOI: 10.1007/s11738-018-2770-0

Plant growth-promoting rhizobacteria (PGPR) have demonstrated its importance in agriculture globally including beneficial dynamics change in plant rhizosphere leading better tolerance towards abiotic stresses. Hundred and one bacterial cultures from sugarcane rhizosphere zone of > 50 years of sugarcane growing fields were isolated using standard protocols and were further subjected to in vitro screening to visualize their impact on plant growth. Of these, two cultures based on biochemical test and 16S rRNA gene sequences were classified as Bacillus subtilis (BSSC11) and Bacillus megaterium (BMSE7). Sugarcane settlings exposed to these strains exhibited more nutrient content, improved growth in terms of early sprouting, increased vigor (high shoot and root weight) and better antioxidant enzyme system ability including quantitative overexpression of superoxide dismutase (SOD) isoforms over controls. Treated cane seed (setts) with B. megaterium culture exhibited high expression of invertase genes which facilitated early and improved growth of settlings through increased inversion of sucrose to glucose and fructose. When these settlings were exposed to drought, a significant decrease in SOD enzyme activity and increase in proline content was observed especially in B. megaterium -exposed samples indicating less generation of free radicals in inoculated than those of non-inoculated samples where SOD activity increased significantly. This is apparently a first study of PGPRs isolated from continuous growing sugarcane fields on the growth and vigor of sugarcane settlings in vivo and further hypothesized that a multiple chain of events is involved in imparting better crop growth of PGPR-exposed settlings both under normal and stress conditions.