Do Endophytes Improve Physiological Traits and Functions of Host Plants? a Meta-Analysis of Endosymbiosis Effects on Plant Physiology.

Endophytes are symbiotic bacteria, fungi, and yeast living inside the intercellular spaces or vascular systems. Various plants are known to host these beneficial microorganisms to stand under unfavorable environmental conditions. As an effort to find a solution to environmental challenges, using endophytic symbionts to improve host plants performance has been suggested as a sustainable method in agricultural ecosystems. A few meta-analytic reports have pointed out endophyte effects on increses in biomass gain. However, those papers find mechanistic explanations from different areas of plant physiology. Enhancement of nutrient uptake, production of growth promoting hormones, provision of essential nutrients, etc. Their effects on functional traits of plants have not been assessed. To fully understand their benefits on generic physiological responses from individual study, and to further fill our knowledge gap between microbial mechanism and plant fitness component, we conducted a meta-analysis on endophyte effects on the key physiological parameters related to photosynthesis and water relations of plants: Chlorophyll content, photochemical efficiency, net CO₂ assimilation rate, transpiration rate, and intrinsic water use efficiency.