Diversity and Functionality of Culturable Endophytic Bacterial Communities in Chickpea Plants.

Maria Félix,Bernard Glick,Esther Menéndez,Solange Oliveira,Sakshi Singh,Clarisse Brígido,Mário Carvalho,Maria Tavares

doi:10.3390/plants8020042

Abstract

The aims of this study were to isolate, identify and characterize culturable endophytic bacteria from chickpea (Cicer arietinum L.) roots grown in different soils. In addition, the effects of rhizobial inoculation, soil and stress on the functionality of those culturable endophytic bacterial communities were also investigated. Phylogenetic analysis based on partial 16S rRNA gene sequences revealed that the endophytic bacteria isolated in this work belong to the phyla Proteobacteria, Firmicutes and Actinobacteria, with Enterobacter and Pseudomonas being the most frequently observed genera. Production of indoleacetic acid and ammonia were the most widespread plant growth-promoting features, while antifungal activity was relatively rare among the isolates. Despite the fact that the majority of bacterial endophytes were salt- and Mn-tolerant, the isolates obtained from soil with Mn toxicity were generally more Mn-tolerant than those obtained from the same soil amended with dolomitic limestone. Several associations between an isolate’s genus and specific plant growth-promoting mechanisms were observed. The data suggest that soil strongly impacts the Mn tolerance of endophytic bacterial communities present in chickpea roots while rhizobial inoculation induces significant changes in terms of isolates’ plant growth-promoting abilities. In addition, this study also revealed chickpea-associated endophytic bacteria that could be exploited as sources with potential application in agriculture.

Highlights

Plants, including legumes, are normally colonized by a wide range of different microorganisms [1].A subset of those microbes consists of endophytic bacteria, bacteria that colonize the internal tissues of a plant without any apparent sign of infection or negative effects on the host plant [2], and represents a widespread and ancient relationship [3]
Besides the typical nitrogen-fixing endosymbionts, collectively named as rhizobia, that legume plants harbor inside their root nodules, other endophytic bacteria are usually found within different legume tissues
Several previous studies have indicated that some of these bacteria are able to promote plant growth and health [22], few reports have focused their attention on the Besides the typical nitrogen-fixing endosymbionts, collectively named as rhizobia, that legume plants harbor inside their root nodules, other endophytic bacteria are usually found within different legume tissues

Summary

Introduction

Plants, including legumes, are normally colonized by a wide range of different microorganisms [1].A subset of those microbes consists of endophytic bacteria, bacteria that colonize the internal tissues of a plant without any apparent sign of infection or negative effects on the host plant [2], and represents a widespread and ancient relationship [3]. Few associations between plants and endophytes have been studied in detail, with the legume-rhizobia association being the exception These bacteria can promote plant growth in a variety of ways. Some studies conducted in soybean showed that plant growth stage and tissue, treatment with the herbicide glyphosate, nodulation phenotype and nitrogen level had different effects on the diversity and taxonomic composition of the endophytic bacterial community [8,16,17,18]. Whether these changes have specific consequences for plant growth and health remains unknown

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