Bacillus spp. from rainforest soil promote plant growth under limited nitrogen conditions

Authors: HUANG, XING-FENG - Colorado State University; ZHOU, DONGMEI - Colorado State University; GUO, JIANHUA - Nanjing Agricultural University; Manter, Daniel; REARDON, KENNETH - Colorado State University; VIVANCO, JORGE - Colorado State University

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2014
Publication Date: 1/8/2015
Publication URL: http://DOI: 10.1111/jam.12720
Citation: Huang, X., Zhou, D., Guo, J., Manter, D.K., Reardon, K.F., Vivanco, J.M. 2015. Bacillus spp. from rainforest soil promote plant growth under limited nitrogen conditions. Journal of Applied Microbiology. 118:672-684. DOI: 10.1111/jam.12720.

Interpretive Summary: This study evaluated bacterial isolates for their ability to improve plant growth under nitrogen limiting conditions. Four bacterial isolates including one Bacillus subtilis, two B. atrophaeus, and one B. pumilus significantly increased the growth of corn (Zea mays L.) and tomato (Solanum lycopersicum) under greenhouse conditions. In particular, the bacterial inoculants promoted tomato growth under both high and low soil nitrogen conditions. Additional studies showed that volatile chemicals produced by the bacterial isolates could promote Arabidopsis growth, and induced the expression of genes related to IAA production. In addition to alleviating nutrient stress, these isolates were also found to induce systemic resistance (ISR) against Pseudomonas syringae pv tomato DC3000 in Arabidopsis. Bacterial inoculants, such as those identified here, that have wide adaptability to different crops, soils, and environmental conditions provide a viable option to reduce our reliance on agricultural amendments derived from fossil-based fuels. The bacterial strains isolated here from a non-agricultural site constitute new plant growth promoting bacterial strains that could be developed for agricultural uses.

Technical Abstract: Aims: The aim of this study was to evaluate effects of PGPR (Plant Growth Promoting Rhizobacteria) isolated from rainforest on different plants under limited nitrogen conditions. Methods and Results: Bacterial isolates from a Peruvian rainforest soil were screened for plant growth promoting effects on Arabidopsis (Col-0). Four selected isolates including one Bacillus subtilis, two B. atrophaeus, and one B. pumilus significantly promoted growth of Zea mays L. and Solanum lycopersicum under greenhouse conditions. Moreover, the PGPRs significantly promoted growth of S. lycopersicum in both low and nitrogen-amended soil conditions. These PGPR strains were further studied to obtain insights into possible mechanisms of plant growth promotion. Volatile chemicals from those isolates promoted Arabidopsis growth, and the expression of genes related to IAA production were induced in the Arabidopsis plants treated with PGPRs. Further, selected PGPR strains triggered induced systemic resistance (ISR) against Pseudomonas syringae pv tomato DC3000 in Arabidopsis. Conclusions: PGPR strains isolated from the rainforest soil promoted the plant growth of Arabidopsis, corn and tomato. Significance and Impact of the study: New PGPR that have wider adaptability to different crops, soils, and environmental conditions are needed to decrease our reliance on agricultural amendments derived from fossil-based fuels. The PGPRs isolated from a non-agricultural site constitute new plant growth promoting strains that could be developed for agricultural uses.