Genome analysis and screening of Plant-Growth-Promoting Rhizobacteria isolated from halophytes and drought-tolerant plants

Environmental stresses such as drought, salinity, or temperature extremes can severely injure plants and are among the major constraints to plant growth and crop production worldwide. In particular, in the drought stricken areas in Greece, plants encounter a combination of drought (absence of rainfall), high temperatures and salinity stress, resulting to greater harmful impact on plant growth and productivity compared to individually stresses per se. In the current global agenda, issues with agricultural significance such as biodiversity loss, water depletion and pollution, in combination with the fact that modern agricultural activities demand extensive water consumption, all pose new challenges for researchers in order to reduce the water use and produce agricultural products of high quality. Furthermore, research community should also consider the consumer demands for lower inputs (agrochemicals and low carbon footprint) in the agricultural products. In this context, the integration of beneficial plant-microbe interactions that promote plant growth and stress tolerance may represent a promising sustainable solution to improve agricultural production under unfavourable environments.Plant-growth-promoting rhizobacteria (PGPR) aggressively colonize plant roots of many plant species and augment plant growth and immunity to pathogen attacks (Dimkpa et al, 2009; Yang et al, 2009). Some PGPR strains produce cytokinin and antioxidants, while others induce the degradation of the ethylene precursor 1-aminocyclopropane- 1-carboxylate (ACC) by bacterial ACC deaminase (Figueiredo et al, 2008). Nevertheless, a comprehensive study on gene and metabolite networks underlying the mechanisms by which these bacteria alleviate the oxidative damage elicited by certain stress factors is still missing. Next generation sequencing technologies (NGS) have enabled whole genome sequencing of bacteria and other organisms, while the systematic analysis of whole genome data has aided the understanding of the molecular genetics of many bacterial species (Gupta et al, 2014). Through this proposed project, the integration of physiological, biochemical, transcriptomic and metabolomic responses of PGPR-inoculated tomato plants under stress will aid us better understand i) the bacterial colonization strategies, ii) the biochemical/molecular mechanism of plant responses, and iii) ultimately how to improve plant productivity and performance under unfavourable conditions.Overall, the research proposal aims to isolate PGPR from the semi-arid Mediterranean region, and to study the effect of the interactions between these PGPR and tomato plants grown under abiotic stress (drought and salt stress). In particular, the main objectives/goals of the study are:1. to isolate bacteria from the rhizosphere of stress tolerant plants and to evaluate in vitro their functional traits that are associated with promoting plant stress tolerance,2. to study the effects of various PGPR on plant growth under drought and salt stress in order to select the strains that in vivo can promote growth and resistance to stress,3. to characterize the isolated strains using whole genome sequencing, and to identify loci implicated in plant stress tolerance,