Mechanisms and Use of Plant Growth-Promoting Bacteria to Improve Seed Germination in Adverse Environments

Abstract

Seed dormancy and germination are highly regulated processes under the control of various factors, among which stand out the internal balance of abscisic acid (ABA)/gibberellin (GA) and environmental conditions that impact this ratio. Germination determines when plants enter to natural or agricultural ecosystems. It represents the basis of agricultural production, and several agricultural strategies have been implemented to improve it. Plant Growth Promoting Rhizobacteria (PGPR) are ubiquitous soil microorganisms that favorably impact plant performance through pathogen control, nutrient uptake, tolerance to stress conditions, and even the production plant growth regulators, which impact both seed germination and subsequent plant development. Seeds germinate as soon as they are embedded and sown, so even when most studies have focused on the mechanisms that depend on plants themselves, it is evident that a better knowledge of plant-microorganism interactions could be useful to improve agricultural production and achieve sustainable and ecologically friendly agriculture. Here, after describing the endogenous mechanisms controlling germination and dormancy, we will update the information about the potential of PGPR to improve germination, and we will give a general overview of their use in agriculture systems to guarantee the food security in the years to come.