Hydrogen Peroxide Is Involved In Abscisic Acid-induced Adventitious Rooting In Cucumber Under Drought Stress And Its Analysis Of Differential Protein Expression

Abscisic acid?ABA?as a signal molecule might be involved in the regulation of plant growth and development.As well as,ABA as an essential signaling role responses might be involved in responsing to various abiotic stresses.Hydrogen peroxide?H₂O₂?,as a kind of reactive oxygen species,has been considered as an important signaling molecule that mediates various physiological and biochemical processes in plants.In order to further investigate the mechanism of ABA induce the development of adventitious root,we have showed the relationship of signaling network among H₂O₂ and ABA during adventitious rooting under drought stress.Then,we have drawed the following conclusions:1.When compared with the control,adventitious root number and root length were significantly decreased under drought stress,however,both ABA and H₂O₂ significantly inhibited the decrease in adventitious root number and root length caused by drought stress,suggesting that the promotive effects of ABA and H₂O₂ induced adventitious rooting under drought stress.2.Adventitious root number and root length of PEG + ABA + CAT or PEG + ABA+ DPI treatments were significantly lower than those of PEG + ABA treatment,however,that significantly greater than those of PEG treatment.All the results indicated that the promotive effects of ABA-induced adventitious rooting under drought stress were suppressed by synchronous presence of CAT or DPI.3.The proteomic analysis of cucumber explants treatmented by ABA or H₂O₂ under drought stress.51 proteins were identified and they were grouped into ten categories according to their biochemical functions,including photosynthesis?22.92%?,carbohydrate binding-related proteins?6.25%?,amino acid metabolism?4.17%?,defense response?20.83%?,protein degradation/folding and modification?10.42%?,translation and transcription?10.42%?,energy and metabolism?18.75%?,cell division?2.08%?,signal transduction?2.08%?and unknown?2.08%?.Among the proteins related to photosynthesis,chloroplast transketolase and two ribulose-1,5-bisphosphate carboxylase large subunit proteins exhibited decreased in PEG,sedoheptulose-1,7-bisphosphatase and Oxygen-evolving enhancer protein1 increased in PEG + ABA treatment,however,decreased in PEG + ABA+ CAT treatment.Two proteins?lactoylglutathione lyase and heme-binding protein 2?related to defense response exhibited increased relativeabundance in treatment with PEG + ABA,however,decreasing in PEG + ABA + CAT treatment.Glutamate-glyoxylate aminotransferase 2-like related to amino acid metabolism exhibited decreased relative abundance in treatment with PEG + ABA+ CAT,and another protein glutamine synthetase increased in PEG + ABA treatment.All the results suggesting that endogenesis H₂O₂ might be involved in ABA-induced adventitious root development of cucumber explants under drought stress by enhancing the abundance of proteins related to photosynthesis,defense response and amino acid metabolism.A total of five proteins involved in protein folding,modification and degradation,20 k Da chaperone protein and cysteine protease decreased in PEG + ABA+ CAT treatment,the other proteins in PEG and PEG + ABA treatments were significantly up-regulated expression,and five proteins involved in transcription,suggesing that ABA by regulating protein translation modified to ease the inhibitory effect of drought on cucumber adventitious rooting.The 12-identified proteins related to carbon metabolism and energy metabolism,two proteins enoyl-acyl-carrier-protein reductase and aldo-keto reductase 4exhibited decreased in PEG + ABA + CAT treatment and the other proteins exhibited increased relative abundance in PEG and PEG + ABA treatments.Those proteins were mainly involved in ATP hydrolysis and glycolysis processes,indacting that ABA increased carbon metabolism and energy metabolism of cucumber explants under drought stress.Thus alleviating the drought stress-induced energy shortage by ATP hydrolysis and glycolysis processes.One protein related to cell division?centromere-associated protein E isoform X2?exhibited increased relative abundance in treatment with PEG + ABA,shows that ABA increased cell multiplication of cucumber explants under drought stress.The results showed that endogenous H₂O₂ is involved in the regulation of ABA on photosynthesis,defense response,energy and protein folding,modification and degradation of proteins related to participate in adventitious rooting induced by ABA under drought stress.4.ABA and H₂O₂ treatments activated cell cycle with the transition of cell from G1 to S phrase.ABA and H₂O₂ promoted adventitious root development under drought stress through activating cell cycle for cell division rapidly in cucumber.However,CAT or DPI depressed the induction of ABA on cell cycle phrase.Thus,that ABA inducesadventitious root development under drought stress by regulating of H₂O₂ on cell cycle avtivation in cucumber.