Phomopsis Liquidambaris Contributes to the Decease of Ethylene Biosynthesis in Rice under Salt Stress via Inhibiting the Activity of 1-Aminocyclopropane-1-Carboxylate Deaminase

Abstract The endophytic fungus Phomopsis liquidambaris is characterized as a plant growth-promoting agent under salt stress, but its mechanism is unknown. Herein, 1-Aminocyclopropane-1-Carboxylate Deaminase (ACCD) from the strain was confirmed that it had the ability of utilizing 1-Aminocyclopropane-1-Carboxylate as the sole nitrogen source. The full-length ACCD gene was 1,152 bp, which encodes a mature protein of 384 amino acids with a molecular mass of 41.53 kDa. The ACCD activity was 3.9-fold in 3 mmol L− 1 ACC by qRT-PCR under salt stress comparing with no salt tress. Ethylene production was increased to 34.55–70.60% and reduced the growth of rice by 23–69.73% under salt stress. Inoculation of P. liquidambaris increased root-shoot length, fresh and dry weight, and overall growth of stressed rice seedlings. ACC accumulation, ACC synthase and ACC oxidase activities increased in salt-treated rice seedlings, while they were significantly reduced when P. liquidambaris was inoculated into Rice by qRT-PCR. It therefore can be concluded that P. liquidambaris can be used as a plant growth promoting fungus against salt stress and other biotic or abiotic stresses.