Changes and Correlation Between Physiological Characteristics of Rhododendron simsii and Soil Microbial Communities Under Heat Stress

Abstract

The relationship between Rhododendron simsii and its soil microbial community under heat stress was not clear. In this study, the effects of heat stress on the physiological characteristics, soil physicochemical properties and soil microbial community structure of R. simsii were investigated. The experimental control (CK) was set as day/night (14/10 h) 25/20°C and experimental treatments were set as light heat stress (LHS) 35/30°C and high heat stress (HHS) 40/35°C. Our results showed that, compared with CK, LHS treatment significantly increased malondialdehyde, hydrogen peroxide, proline and soluble sugar contents, as well as catalase and peroxidase activities, while HHS treatment significantly increased ascorbate peroxidase activity and decreased chlorophyll content. Compared with CK, LHS treatment significantly reduced soil ammonium-nitrogen and nitrate-nitrogen content, while HHS significantly increased soil ammonium-nitrogen content. Compared with CK, both treatments changed the soil microbial community structure. For bacterial community, LHS and HHS treatment resulting in the significant enrichment of Burkholderia-Caballeronia-Paraburkholderia and Occallatibacte, respectively. For fungal community, LHS treatment resulting in the significant enrichment of Candida, Mortierella and Boothiomyces. The redundancy analysis showed that plant physiological characteristics, soil ammonium-nitrogen content were significantly correlated with the soil microbial community. Therefore, heat stress altered the soil microbial community structure, and affected the availability of soil available nitrogen, which in turn affected the physiological characteristics of R. simsii. We suggest that soil microbial community may play an important role in plant resistance to heat stress, and its mechanism deserves further study.

Changes of endophytic microbial community in Rhododendron simsii roots under heat stress and its correlation with leaf physiological indicators

“…Studies have shown that heat stress significantly reduced the content of carbon, N, and phosphorus in plant rhizosphere soil, resulted in a decrease of plant biomass ( Khan et al, 2021 ). We also found that heat stress can change soil available N content, to influence the absorption of nutrients by plants, brought changes to various plant physio-logical indicators ( Guo et al, 2022 ; Liu, L. et al, 2022 ).…”

“…The data in this section are quoted from our previous study ( Liu, L. et al, 2022 ). Compared with CK, MHS and HHS significantly increased the content of MDA (239 and 125%), H2O2 (70 and 56%), soluble sugar (149 and 139%), and the activity of CAT (138 and 93%).…”

“…Indophenol blue colorimetric method was applied to determine soil ammonium N (NH 4 + -N), and ultraviolet spectrophotometry was used for the determination of soil nitrate N (NO 3 − -N). This part is the same as our previous research (Liu, L. et al, 2022).…”

“…Rhododendron spp. is a large group of Ericaceae, which is well-known for its highly-presentable flowers commonly used for horticultural display ( Li et al, 2021 ; Liu, L. et al, 2022 ). In recent years, its value on medicinal uses been studied, and its character of ecological friendly have also been recognized ( Lin et al, 2019 ; Li et al, 2021 ).…”

“…Under mild heat stress, the plants might self-regulate through a series of reactions, but high-heat stress often leads to protein denaturation inside the plants to self-regulation. Nevertheless, during the photosynthetic process of the plants, the main destructed site of the photosynthetic mechanism is photosystem II, high temperature leads to the inactivation of photosynthetic proteins, which has a negative impact on the synthesis of photosynthetic pigments, and makes plants prone to appear yellow leaves under heat stress ( Xi et al, 2020 ; Liu, L. et al, 2022 ).…”