Exogenous GABA enhances muskmelon tolerance to salinity-alkalinity stress by regulating redox balance and chlorophyll biosynthesis

摘要: Salinity-alkalinity stress is one of the major abiotic stresses affecting plant growth and development. γ-Aminobutyrate (GABA) a non-protein amino acid that functions in tolerance. However, interactions between cellular redox signaling chlorophyll (Chl) metabolism involved GABA-induced salinity-alkalinity tolerance plants remains largely unknown. Here, we investigated role GABA perceiving regulating biosynthesis oxidative induced by muskmelon leaves. We also evaluated effects hydrogen peroxide (H2O2), glutathione (GSH), ascorbate (AsA) on increased malondialdehyde (MDA) content, relative electrical conductivity (REC), activities superoxide dismutase (SOD), peroxidase (APX) dehydroascorbate reductase (DHAR). decreased shoot dry fresh weight leaf area, reduced (GSH AsA) contents, (GR) monodehydroascorbate (MDAR). By contrast, pretreatment with GABA, H2O2, GSH, or AsA significantly inhibited these stress-induced effects. The ability to relieve was when production endogenous H2O2 inhibited, but not affected inhibiting GSH production. Exogenous respiratory burst oxidase homologue D (RBOHD) genes expression accumulation under normal conditions content stress. synthesis precursors glutamate (Glu), δ-aminolevulinic (ALA), porphobilinogen (PBG), uroporphyrinogen III (URO III), Mg-protoporphyrin IX (Mg-proto IX), protoporphyrin (Proto protochlorophyll (Pchl), thereby increasing Chl content. Under stress, exogenous ALA contents Glu, PBG, URO III, Mg-proto IX, Proto Pchl, Chl. treated had no consistent trends precursor contents. elevated may act as signal molecule, while function antioxidants, These factors maintain membrane integrity which essential for ordered biosynthesis. Pretreatment mitigated caused excessive its precursors, avoid photooxidation injury.