SYMRK significantly affected AMF symbiosis and plant growth in maize

Arbuscular mycorrhizal fungi (AMF) are important symbiotic microorganisms in the soil that form reciprocal relationships with most plants to enhance their ability to absorb nutrients from the soil. The establishment of symbiosis between plants and AMF involves complex molecular mechanisms, and the SYMRK (Symbiosis receptor-like kinase) plays a pivotal role in the establishment of symbiosis. Maize (Zea mays) is a globally significant crop and one of the hosts for AMF, but research on AMF symbiosis-related genes in maize is limited. In this study, we identified a symbiosis receptor-like kinase in maize, named ZmSYMRK, which corresponds to the ortholog gene OsSYMRK in rice. ZmSYMRK encodes a cell membrane-localized protein kinase that is crucial for AMF colonization. We demonstrated that ZmSYMRK deletion resulted in severe defects in maize symbiosis with AMF. The colonization rates of zmsymrk mutants were significantly reduced at three different time points, and the colonization defects did not recover with prolonged colonization time. Furthermore, the deletion of the ZmSYMRK gene severely affected plant growth under low phosphorus conditions, and the growth defects of the mutants were even more pronounced after symbiosis. We conclude that ZmSYMRK plays a crucial role in both plant growth and the establishment of symbiotic relationships with AMF.