Alleviation of Abiotic and Biotic Stresses in Plants by Azospirillum

Abstract

In the face of global changes, plants must adapt to a wide range and often combined biotic and abiotic stresses that seriously impaired plant growth and development. Plants develop complex strategies to deal with water stress conditions, soil fertility losses, soil pollutions, pests, and disease. Emerging evidence suggest the involvement of common hormonal players in plant defense signaling pathways triggered in response to biotic and abiotic stresses. Besides plant strategies, plant growth-promoting rhizobacteria (PGPR), which colonize the root system and establish cooperative interactions with plants can improve their growth and help them to adapt to and cope with multiple stresses including drought, salinity, heavy metal pollutions, and parasites. Accordingly, PGPR supply added values to the plant defense strategies by expressing many relevant functions for modulating the plant hormonal balance, increasing nutrients supply to the plant, improving the functional and phy sical properties of protective barriers against plant parasites. Among PGPR, Azospirillum strains were long viewed as biofertilizers and less as biocontrol agents. It is becoming evident that Azospirillum is able to protect plants against a myriad of detrimental conditions. This review provides an update of works regarding the ability of Azospirillum strains to alleviate plant stress and brings out the relevant involved plant-benefi cial functions. Developing PGPR-based bio-inoculants is a promising strategy to improve the growth and health of crops and develop sustainable agriculture.

Plant Growth Promoting Rhizobacterial Mitigation of Drought Stress in Crop Plants: Implications for Sustainable Agriculture

“…One major response of plants is the adjustment of the osmotic potential of cells through the accrual of compatible solutes such as phenolics, proline (amino acids), trehalose (sugar), glycine betaine, amongst others [49,50], in response to drought stress [35,51]. These compatible solutes act as osmoprotectants, shielding cells from dehydration and also aiding the detoxification of stressed cells from detrimental levels of ROS.…”

The influence of plant growth-promoting rhizobacteria in plant tolerance to abiotic stress: a survival strategy

“…Among the nitrogen fixers of atmospheric N to plants for its nutritional needs, Azospirillum is a good farmers’ friend that contributes in enriching the soil and enabling plants to thrive under abiotic stress. This microbe, which possesses a list of unique attributes such as auxin production, deaminase enzyme production, siderophore–iron trapping substance, nitrogen fixation, exopolysaccharide, etc., enables its associates (plants) to tolerate drought as well as salt disturbances (Cruz et al 2017a ; Vacheron et al 2015 ).…”

“…Azospirillum generates biocidal substances (bacteriocins, hydrogen cyanide, proteolytic enzymes, siderophores) capable of destroying pathogen/invaders of plants and encourages plants to tolerate abiotic stresses as well as living organisms inducing stress on plants. It could be regarded as a plant growth-promoting bacteria and is widely studied by researchers (Vacheron et al 2015 ; Creus et al 2010 ). The contribution of this organism in nutrient uptake by plant as well as water-facilitated uptake is well documented.…”

Rhizosphere Microbiome Modulators: Contributions of Nitrogen Fixing Bacteria towards Sustainable Agriculture

“…Other extrinsic factors like climate change and anthropogenic activities can also modulate the microbial communities in a specific plant host [ 23 ]. In particular, anthropogenic activity such as the use of N-based chemical fertilizer is associated with environmental destruction [ 24 ].…”