Microbe-Mediated Thermotolerance in Plants and Pertinent Mechanisms- A Meta-Analysis and Review

Abstract

Microbial symbionts can mediate plant stress responses by enhancing thermal tolerance, but less attention has been paid to measuring these effects across plant-microbe studies. We performed a meta-analysis of published studies as well as discussed with relevant literature to determine how the symbionts influence plant responses under non-stressed versus thermal-stressed conditions. As compared to non-inoculated plants, inoculated plants had significantly higher biomass and photosynthesis under heat stress conditions. A significantly decreased accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) indicated a lower oxidation level in the colonized plants, which was also correlated with the higher activity of catalase, peroxidase, glutathione reductase enzymes due to microbial colonization under heat stress. However, the activity of superoxide dismutase, ascorbate oxidase, ascorbate peroxidase, and proline were variable. Our meta-analysis revealed that microbial colonization influenced plant growth and physiology, but their effects were more noticeable when their host plants were exposed to high-temperature stress than when they grew under ambient temperature conditions. We discussed the mechanisms of microbial conferred plant thermotolerance, including at the molecular level based on the available literature. Further, we highlighted and proposed future directions toward exploring the effects of symbionts on the heat tolerances of plants for their implications in sustainable agricultural production.

Glomus mosseae improved the adaptability of alfalfa (Medicago sativa L.) to the coexistence of cadmium-polluted soils and elevated air temperature

“…Some studies have shown that AMF can improve contents of osmolytes, such as soluble sugars and proteins, in host plants exposed to Cd or heat stress (Wu, 2011;Dastogeer et al, 2022;Wang et al, 2022a), which was consistent with our results under ET + Cd. The stimulation of G. mosseae on two substances suggested that AMF might improve the osmotic regulation ability of alfalfa against oxidative stress from the coexistence of ET and Cd.…”

Seed endophytic bacterial profiling from wheat varieties of contrasting heat sensitivity

“…The WSEB isolates from heat T varieties were well established under an increasing temperature range when compared to the heat S variety. The ability of these endophytes might increase the bounds of temperature tolerance of heat T varieties ( Dastogeer et al., 2022 ). This was in line with the studies that growth of spot inoculated purified microbial isolates on medium plates under selection pressure of some chemicals or incubation conditions is considered as tolerant to respective stress condition.…”

Phyto-microbiome to mitigate abiotic stress in crop plants

“…It has been seen that heat stress increases the concentration of amino acids while decreasing the concentration of starch, sugars, and lipids. Maltose concentration has been seen to be elevated ( Dastogeer et al, 2022 ). At the molecular level, heat stress leads to protein denaturation and misfolding.…”