Impact of high temperature stress on plant physiological traits and mycorrhizal symbiosis in maize plants accessed under microcosm conditions

Authors: MATHUR, SONAL - Oak Ridge Institute For Science And Education (ORISE); AGNIHOTRI, RICHA - Icar-Indian Institute Of Maize Research; SHARMA, MAHAVEER - Icar-Indian Institute Of Maize Research; Reddy, Vangimalla; JAJOO, ANJANA - Devi Ahilya Vishwavidyalaya, Indore

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2021
Publication Date: 10/16/2021
Citation: Mathur, S., Agnihotri, R., Sharma, M.P., Reddy, V., Jajoo, A. 2021. Impact of high temperature stress on plant physiological traits and mycorrhizal symbiosis in maize plants accessed under microcosm conditions. The Journal of Fungi. 7:867. https://doi.org/10.3390/jof7100867.
DOI: https://doi.org/10.3390/jof7100867

Interpretive Summary: Increasing temperature has negative effect on plant growth and development. Arbuscular mycorrhizal fungi (AMF) help plants to cope up under stress by improving plant fitness. In this study, the impact of high temperature stress on photosynthetic parameters in maize plants was studied with and without fungi. Plants with fungi grew better under high temperature stress as compared to plants grown without them. Thus, AMF protected maize plants from damaging effect of high temperature stress.

Technical Abstract: Increasing global temperature has negative impact on plant growth and development. Arbuscular Mycorrhizal Fungi (AMF) help plants to cope up under stress by improving plant fitness. In this study, the impact of high temperature stress on physiological (above-ground) traits in maize plants was carried out in microcosms. Along with photosynthetic parameters, as a soil quality indicator, phospholipid fatty acid (PLFA) biomarkers of soil microbial communities were also assessed in AMF and non-AMF maize plants exposed to high temperature (HT). Plants were grown during extreme summer conditions. Maximum temperature at the time of experiments was found to be, 43 -44°C (month of May) (Indore, 22°44'N), (www.acuweather.com, ICAR-IISR Indore, India). The experiment design was laid out in a completely randomized design with the following treatments: Control = maize plants were grown in normal soil and plants were not subjected to high temperature; AMF = maize plants were grown in AMF enriched soil and plants were not subjected to high temperature; HT = maize plants were grown in normal soil and experienced higher temperature (ambient temperature during summer 43 °C); AMF+HT = maize plants were grown in AMF enriched soil and experienced high temperature stress. AM enriched HT plants were found to perform better under high temperature stress as compared to non-AMF enriched HT plants. The photosynthetic parameters like quantum yield of photosystem (PS) PSII and PSI, linear electron transport and qP, reduced in HT exposed plants while they were resumed in AMF enriched HT plants. The fraction of open PSII centers increased for AMF plants while these decreased for HT plants under high temperature. Total chlorophyll content increased in AMF+HT plants as compared to HT plants. AMF+HT plants not only had better physiological parameters under high temperature but showed significantly higher AM-signature 16:1'5cis neutral lipid fatty acid (NLFA), AMF spore density in soil and colonization in roots and decline in lipid peroxidation (MDA content). This indicated that enriched plants had higher AMF active live biomass which enhanced water and nutrient uptake, photosynthetic efficiency, accumulation of osmolytes and thus protected plants from oxidative damage. This study provides understanding of plant's survival and fitness exposed to high temperature conditions under AMF and non-AMF enriched plants. AMF facilitated the plants to maintain integrity and stability of photosynthetic apparatus under HT stress. This is the first study combining plant physiological traits (above-ground) with PLFA (below-ground) parameters simultaneously.