Interaction of phytohormone-producing rhizobia with sugarcane mini-setts and their effect on plant development

• Published in: Plant and soil Vol. 451; no. 1-2; pp. 221 - 238
• Main Authors: Ferreira, Natália S., Matos, Gustavo F., Meneses, Carlos H. S. G., Reis, Veronica M., Rouws, Janaina R. C., Schwab, Stefan, Baldani, José I., Rouws, Luc F. M.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.06.2020; Springer; Springer Nature B.V
• Subjects: Acetic acid; Analysis; Biomedical and Life Sciences; Colonization; Cytokinins; Ecology; Evaluation; Gibberellins; High-performance liquid chromatography; Hormones; Indoleacetic acid; Inoculation; Life Sciences; Liquid chromatography; Low concentrations; Microbiomes; Organic acids; Phylogeny; Phytohormones; Plant growth; Plant Physiology; Plant Sciences; RecA protein; Regular Article; RpoB protein; Sequence analysis; Soil Science & Conservation; Sugarcane; Transplantation; Zeatin; Brazil; GC-MS; Sprouting; Gibberellins; Plant growth promoting bacteria; Endophytic bacteria; HPLC; Confocal laser scanning microscopy
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-019-04388-0

Aims Rhizobia are common members of plant microbiomes. This study aimed to evaluate if rhizobia can colonize sugarcane mini-setts and if and how they affect sprouting and morphological traits of plant development. Methods Bradyrhizobium sacchari strain BR 10280 T and Rhizobium sp. strain BR 10268 were inoculated on sugarcane mini-setts and sprouting and plant development were evaluated. Bacterial production of hormones and their effect on plant growth were studied using HPLC and GC-MS / SIM and sugarcane sprouting assays. Colonization was investigated by colony counting and CLSM. Sequence analysis of recA , gyrB and rpoB genes was applied to refine the phylogenetic classification of strain BR 10268. Results BR 10268 had a positive effect on sugarcane mini-sett sprouting and shoot and root growth at 30 and 75 days after transplantation (DAT) and colonized sprouting mini-sett tissues. Few significant effects were observed for B. sacchari BR 10280 T . Cell-free BR 10268 supernatant was found to contain gibberellins (GAs) and low concentrations of indole-3-acetic acid (IAA) and trans-zeatin; treatment of mini-setts with GA 3 (0.15 or 1.5 μg mL −1 ) affected sprouting in a similar manner as BR 10268 inoculation. BR 10268 was found to be phylogenetically close to R. freirei . Conclusions Rhizobium sp. BR 10268 positively affects sprouting and growth of sugarcane, probably via production of plant hormonal substances, notably gibberellins, thus naturally occurring rhizobia may have potential as sugarcane inoculants.