Hydrogen peroxide mediates spermidine-induced autophagy to alleviate salt stress in cucumber.

In this study, we demonstrated that spermidine (Spd), a kind of polyamine, was involved in the regulation of salt tolerance through activating the expression of ATG (autophagy-related) genes and the formation of autophagosomes in cucumber under salt stress. Furthermore, NADPH oxidase-derived apoplastic H2O2-mediated Spd-induced salt tolerance and autophagy. Exogenous Spd significantly increased the tolerance to salt stress and inhibited the accumulation and ubiquitination of insoluble proteins. Foliar application of Spd promoted the transcript levels of ATG genes and autophagosomes formation. Besides, Spd induced the expression of RBOH (respiratory burst oxidase homolog), and the accumulation of H2O2 both in leaves and roots. However, either pretreatment with dimethylthiourea (DMTU, an H2O2 scavenger) or diphenyleneiodonium chloride (DPI, an inhibitor of NADPH oxidase) reduced Spd-induced accumulation of apoplastic H2O2. Importantly, Spd-induced salt tolerance and autophagy were compromised when plants were pretreated with DMTU or DPI. Furthermore, the silencing of ATG4 and ATG7 reduced Spd-induced salt tolerance and autophagosomes formation. Taken together, these results revealed that RBOH-dependent H2O2 mediated the Spd-induced autophagy and salt tolerance in cucumber. PMID: 33172324 [PubMed - as supplied by publisher]
Source: Autophagy - Category: Cytology Authors: Tags: Autophagy Source Type: research