Physiological mechanism of enhancing salinity tolerance of Gleditsia sinensis Lam. by arbuscular mycorrhizal fungi

Abstract

18Crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling plays an important 19 role in molecular regulation of plant senescence. Our previous works found that SA could 20 delay methyl jasmonate (MeJA)-induced leaf senescence in a concentration-dependent 21 manner. Here, the effect of low concentration of SA (LCSA) application on MeJA-induced 22 leaf senescence was further assessed. High-throughput sequencing (RNA-Seq) results 23 showed that LCSA did not have dominant effects on the genetic regulatory pathways of 24 basal metabolism like nitrogen metabolism, photosynthesis and glycolysis. The 25ClusterONE was applied to identify discrete gene modules based on protein-protein 26 interaction (PPI) network. Interestingly, an autophagy-related (ATG) module was identified 27 in the differentially expressed genes (DEGs) that exclusively induced by MeJA together 28 with LCSA. RT-qPCR confirmed that the expression of most of the determined ATG genes 29 were upregulated by LCSA. Remarkably, in contrast to wild type (Col-0), LCSA cannot 30 alleviate the leaf yellowing phenotype in autophagy defective mutants (atg5-1 and atg7-2) 31 upon MeJA treatment. Confocal results showed that LCSA increased the number of 32 autophagic bodies accumulated in the vacuole during MeJA-induced leaf senescence. 33Collectively, our work revealed up-regulation of autophagy by LCSA as a key regulator to 34 alleviate MeJA-induced leaf senescence. 35

Effects of arbuscular mycorrhizal fungi on the growth and metabolism of perennial ryegrass (Lolium perenne) under salt stress

“…Carotenoids serve as photoprotectants and function as safety valves to release excess energy before it can damage plant cells (Shumskaya and Wurtzel, 2013). One study found that under NaCl stress, the inoculation of AM fungi could significantly promote the growth of Festuca arundinacea and bluegrass, improve the relative content of chlorophyll in leaves, increase the salt tolerance coefficient, and enhance the visual quality of lawns (Yang et al, 2014). Similar results were also found in this experiment, under both salt stress and salt-free stress, inoculation with AM fungi significantly increased the contents of chlorophyll in perennial ryegrass leaves.…”

“…Arbuscular Mycorrhizae (AM) fungus is a beneficial microorganism that is widely distributed in the soil. It can form a symbiosis with plants to regulate their metabolic activities in various ways, including enhancing the absorption of minerals in the soil, promoting growth and development, and enhancing salt tolerance (Yang et al, 2014). Numerous studies have shown that AM fungi can affect the physiological and biochemical processes of plants by infecting their roots and forming arbuscular mycorrhiza, thus alleviating the adverse effects of salt stress.…”