Poor Competitiveness of Bradyrhizobium in Pigeon Pea Root Colonization in Indian Soils

A - Papers appearing in refereed journals

Chalasani, D., Basu, A., Pullabhotla, S. V., Jorrin, B., Neal, A. L., Poole, P. S., Podile, A. R. and Tkacz, A. 2021. Poor Competitiveness of Bradyrhizobium in Pigeon Pea Root Colonization in Indian Soils. mBio. 12 (4), pp. e00423-21. https://doi.org/10.1128/mBio.00423-21

AuthorsChalasani, D., Basu, A., Pullabhotla, S. V., Jorrin, B., Neal, A. L., Poole, P. S., Podile, A. R. and Tkacz, A.
Abstract

Pigeon pea, a legume crop native to India, is the primary source of protein for more than a billion people in developing countries. The plant can form symbioses with N2-fixing bacteria; however, reports of poor crop nodulation in agricultural soils abound. We report here a study of the bacterial community associated with pigeon pea, with a special focus on the symbiont population in different soils and vegetative and non-vegetative plant growth. Location with respect to the plant roots was determined to be the main factor controlling the bacterial community, followed by developmental stage and soil type. Plant genotype plays only a minor role. Pigeon pea roots have a reduced microbial diversity compared to the surrounding soil and select for Proteobacteria, especially for Rhizobium spp., during vegetative growth. While Bradyrhizobium, a native symbiont of pigeon pea, can be found associating with roots, its presence is dependent on plant variety and soil conditions. A combination of 16S rRNA gene amplicon survey, strain isolation, and co-inoculation with nodule-forming Bradyrhizobium spp. and non-N2-fixing Rhizobium spp. demonstrated that the latter is a much more successful colonizer of pigeon pea roots. Poor nodulation of pigeon pea in Indian soils may be caused by a poor Bradyrhizobium competitiveness against nonnodulating root colonizers such as Rhizobium. Hence, inoculant strain selection of symbionts
for pigeon pea should be based not only on their nitrogen fixation potential but, more importantly, on their competitiveness in agricultural soils.

KeywordsPigeon pea; Bradyrhizobium; 16S rRNA gene amplicon; Competition; Bacterial Community
Year of Publication2021
JournalmBio
Journal citation12 (4), pp. e00423-21
Digital Object Identifier (DOI)https://doi.org/10.1128/mBio.00423-21
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeS2N - Soil to Nutrition [ISPG]
Publisher's version
Output statusPublished
Publication dates
Online06 Jul 2021
Publication process dates
Accepted03 Jun 2021
PublisherAmerican Society for Microbiology
ISSN2150-7511

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