Identification of Klebsiella Variicola T29A Genes Involved In Tolerance To Desiccation

Osvaldo Rodríguez-Andrade,Patricia Bernal,Yolanda E Morales-García,Andrés Corral-Lugo,Dalia Molina-Romero,Jesús Muñoz-Rojas,Rebeca D Martínez-Contreras,Verónica Quintero-Hernández,América P Rivera-Urbalejo

doi:10.2174/1874285801913010256

Osvaldo Rodríguez-Andrade, Patricia Bernal + Show 7 more

Open Access

https://doi.org/10.2174/1874285801913010256

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Abstract

Introduction:Several plant-beneficial bacteria have the capability to promote the growth of plants through different mechanisms. The survival of such bacteria could be affected by environmental abiotic factors compromising their capabilities of phytostimulation. One of the limiting abiotic factors is low water availability.Materials and Methods:In extreme cases, bacterial cells can suffer desiccation, which triggers harmful effects on cells. Bacteria tolerant to desiccation have developed different strategies to cope with these conditions; however, the genes involved in these processes have not been sufficiently explored.Klebsiella variicolaT29A is a beneficial bacterial strain that promotes the growth of corn plants and is highly tolerant to desiccation. In the present work, we investigated genes involved in desiccation tolerance.Results & Discussion:As a result, a library of 8974 mutants of this bacterial strain was generated by random mutagenesis with mini-Tn5 transposon, and mutants that lost the capability to tolerate desiccation were selected. We found 14 sensitive mutants; those with the lowest bacterial survival rate contained mini-Tn5 transposon inserted into genes encoding a protein domain related to BetR, putative secretion ATPase and dihydroorotase. The mutant in the betR gene had the lowest survival; therefore, the mutagenized gene was validated using specific amplification and sequencing.Conclusion:Trans complementation with the wild-type gene improved the survival of the mutant under desiccation conditions, showing that this gene is a determinant for the survival ofK. variicolaT29A under desiccation conditions.

Highlights

Several plant-beneficial bacteria have the capability to promote the growth of plants through different mechanisms
We found 14 sensitive mutants; those with the lowest bacterial survival rate contained mini-Tn5 transposon inserted into genes encoding a protein domain related to BetR, putative secretion ATPase and dihydroorotase
Trans complementation with the wild-type gene improved the survival of the mutant under desiccation conditions, showing that this gene is a determinant for the survival of K. variicola T29A under desiccation conditions

Summary

Introduction

Several plant-beneficial bacteria have the capability to promote the growth of plants through different mechanisms. The diversity of bacteria is greater than that of any other group of organisms [1], and many bacterial species have beneficial properties for plants [2 - 5] These beneficial bacteria can promote plant growth through different mechanisms, such as biological nitrogen fixation, phytohormone production and phosphate solubilization [6 - 10]. The survival of beneficial bacteria may be limited by environmental abiotic factors, such as the stress imposed by low water availability [18]. Water is a determining factor for the life of living beings, and the limitation of this resource causes the dehydration of bacterial cells and, in extreme conditions, desiccation [19]. The water content inside cells decreases until it reaches

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