Identification and characterization of endophytic bacteria isolated from in vitro cultures of peach and pear rootstocks.

Fakhra Liaqat,Rengin Eltem

doi:10.1007/s13205-016-0442-6

Abstract

Endophytes are microorganisms which live symbiotically with almost all varieties of plant and in turn helping the plant in a number of ways. Instead of satisfactory surface sterilization approaches, repeatedly occurring bacterial growth on in vitro rootstock cultures of peach and pear was identified and isolated as endophytic bacteria in our present study. Five different isolates from peach rootstocks were molecularly identified by 16S rRNA gene sequencing as Brevundimonas diminuta, Leifsonia shinshuensis, Sphingomonas parapaucimobilis Brevundimonas vesicularis, Agrobacterium tumefaciens while two endophytic isolates of pear were identified as Pseudoxanthomonas mexicana, and Stenotrophomonas rhizophilia. Identified endophytes were also screened for their potential of plant growth promotion according to indoleacetic acid (IAA) production, nitrogen fixation, solubilization of phosphate and production of siderophore. All seven endophytic isolates have shown positive results for IAA, nitrogen fixation and phosphate solubilization tests. However, two out of seven isolates showed positive results for siderophore production. On the basis of these growth promoting competences, isolated endophytes can be presumed to have significant influence on the growth of host plants. Future studies required to determine the antimicrobial susceptibility profile and potential application of these isolates in biological control, microbial biofertilizers and degradative enzyme production.

Highlights

Endophytes are bacteria or fungus which colonize healthy plant tissue, residing within a plant cell or between plant tissues with no apparent symptoms of disease (Nair and Padmavathy 2014)
Five different isolates from peach rootstocks were molecularly identified by 16S rRNA gene sequencing as Brevundimonas diminuta, Leifsonia shinshuensis, Sphingomonas parapaucimobilis Brevundimonas vesicularis, Agrobacterium tumefaciens while two endophytic isolates of pear were identified as Pseudoxanthomonas mexicana, and Stenotrophomonas rhizophilia
Bacterial colonies appeared on sample plates can be well thought-out as endophytic bacteria of peach and pear rootstocks

Summary

Introduction

Endophytes are bacteria or fungus which colonize healthy plant tissue, residing within a plant cell or between plant tissues with no apparent symptoms of disease (Nair and Padmavathy 2014). While living symbiotically with the plants, these bacteria are known to stimulate plant growth by different ways including the production of phytohormones, solubilization of inorganic minerals like phosphate, fixation of atmospheric nitrogen and sequestration of iron. They sometimes offer protection against pathogenic microorganisms and augmentation of ecological constraints such as drought, salinity and heavy metals (Khalifa et al 2015). The presence of bacteria growth in in vitro plant tissue culture is generally declared as contaminants, which must be prohibited and eradicated

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