Biochemical and molecular responses of maize to low and high temperatures in symbiosis with mixed arbuscular mycorrhizal fungi cultures

In this study, changes in mineral element concentrations, physiological parameters, and gene expression of heat shock proteins were investigated in maize plants subjected to mycorrhiza under low and high temperature stress. The application of seven different temperatures (5 °C, 10 °C, 15 °C, 25 °C, 35 °C, 40 °C, and 45 °C) under five different mixed arbuscular mycorrhizal fungi (AMF) culture treatments (M0, M1, M2, M3, and M4) constituted the factors of the experiment. With the application of mycorrhiza, the plant dry weight was found to be the highest at 25 °C, and the M3 group was applied. The highest values in mineral element concentrations were detected at 25 °C in the maize plant, where M4 had N, P, K, Ca, and Fe concentrations; M3 had Cu and Mn concentrations; and M2 had Mg and Zn concentrations. Lipid peroxidation gradually increased with temperature changes in all the applications, and the protective effect of proline was more pronounced at high temperatures than at low temperatures. Antioxidant enzyme activities were altered by applications of mycorrhiza and temperature. For all mycorrhiza applications, the expression of HSP70 and HSP90 reached a maximum at 10 °C, 40 °C, and 45 °C. It has been revealed that low- and high-temperature applications in maize plants cause serious changes in the mycorrhizal symbiosis on the basis of investigated parameters, and these changes occur at different levels depending on the temperature changes and the differences between mixed AMF cultures. However, it can be said that the M3 application has the capacity to facilitate the growth of maize even in conditions of low (-10 °C) and high (45 °C) temperature.