AtALMT9 Modulates Leaf Development and Disease Resistance in <i>Arabidopsis thaliana</i>

Delaying plant aging and death and enhancing immune defenses of plant have beneficial effects on crop production and the continued development of the agricultural economy. In this study, we focused on AtALMT9, which is located in the vacuolar membrane. Specifically, we investigated its functions in Arabidopsis thaliana leaf development and disease resistance. Our physiological analysis revealed that AtALMT9 negatively regulates leaf development and the immune response to pathogenic microorganisms. Moreover, RNA-seq and qRT-PCR analyses indicated leaf aging- and immunity-related genes were significantly differentially expressed in almt9 mutant plants. Furthermore, the impaired leaf development and accelerated disease resistance of the almt9 mutant were due to the decreased contents of chlorophyll and malic acid as well as the increased levels of salicylic acid and jasmonic acid. This study provides new findings in the molecular mechanism underlying the involvements of AtALMT9 in leaf development and disease resistance, potentially providing a theoretical basis for enhancing agricultural productivity.