Enhancing water stress tolerance improves fitness in biological control strains of Lactobacillus plantarum in plant environments.

Núria Daranas,Jesús Francés,Emilio Montesinos,Esther Badosa,Anna Bonaterra,Sudisha Jogaiah

doi:10.1371/journal.pone.0190931

Abstract

Lactobacillus plantarum strains PM411 and TC92 can efficiently control bacterial plant diseases, but their fitness on the plant surface is limited under unfavourable low relative humidity (RH) conditions. To increase tolerance of these strains to water stress, an adaptive strategy was used consisting of hyperosmotic and acidic conditions during growth. Adapted cells had higher survival rates under desiccation than non-adapted cells. Transcript levels and patterns of general stress-related genes increased immediately after the combined-stress adaptation treatment, and remained unaltered or repressed during the desiccation challenge. However, there were differences between strains in the transcription patterns that were in agreement with a better performance of adapted cells of PM411 than TC92 in plant surfaces under low RH environmental conditions. The combined-stress adaptation treatment increased the survival of PM411 cells consistently in different plant hosts in the greenhouse and under field conditions. Stress-adapted cells of PM411 had similar biocontrol potential against bacterial plant pathogens than non-adapted cells, but with less variability within experiments.

Highlights

The development of practical strategies for the sustainable management of plant diseases to minimize the use of environmentally aggressive pesticides pose a challenge to worldwide crop production [1,2]
In order to increase the tolerance to water stress of L. plantarum strains isolated from plant environments, and to improve its epiphytic survival under low relative humidity conditions, a strategy based on the adaptive growth under stress conditions has been developed
Our results with L. plantarum are in agreement with the findings in other Lactobacillus species from fermented foods, that reported a higher tolerance to stress of stationary-phase cells compared to exponential-phase cells [17, 19, 42, 56]

Summary

Introduction

The development of practical strategies for the sustainable management of plant diseases to minimize the use of environmentally aggressive pesticides pose a challenge to worldwide crop production [1,2]. There is a need for finding new and more effective biological control agents (BCA) and biostimulants, and for optimizing the methods by which these new products are made viable, durable, robust and economical [6,7,8]. Lactobacillus plantarum strains have been reported as novel BCA for bacterial diseases control such as fire blight of rosaceous plants [9,10]. In many BCA, a population decline is often observed after application to plants, reducing biocontrol efficiency

Methods

Results

Conclusion