The Effect Of Osmotic Stress And Aba On Anthocyanins Synthesis And Physiological Traits In Purple Non-heading Chinese Cabbage

Non-heading Chinese cabbage(Brassica campestris ssp.chinensis Makino)which belongs to the Cruciferous Brassica,is a kind of welcomed vegetable with abundant nutritions.Purple non-heading Chinese cabbage is a new cultivated species in recent years which is colorful and rich in anthocyanins.Anthocyanins is a kind of natural pigments and it is good to our health.However,the anthocyanins itself is very unstable and it will reduce significantly or change chemical structure when the conditions were not suitable and this will affect the quality and nutritional value of non-heading Chinese cabbage.At present,the effect of osmotic stress and ABA on the purple non-heading Chinese cabbage’s resistance,pigment changes,content of endogenous abscisic acid and gene expressions related to anthocyanin biosynthesis and endogenous abscisic acid biosynthesis have not been reported,therefore,we use purple non-heading Chinese cabbage ’Zi Guan No.1’ as experimental materials and three experimental treatments were set to analyze the effects of osmotic stress and spraying of ABA to the stress tolerance,pigment content and composition,endogenous abscisic acid content and gene expressions related to anthocyanin biosynthesis and endogenous abscisic acid biosynthesis:Dipping root in 250 mg·mL-1 PEG6000 solution(polyethylene glycol 6000,PEG),foliage spraying of 50 μmol·L-1 ABA(abscisic acid,ABA)and spray ddH2O and regular management(CK).Results are as follows:1 The effects of osmotic stress and ABA on the content of MDA,soluble sugar,proline and the activity of SOD,CAT and POD in the leaves of purple non-heading Chinese cabbage.The results showed that:both of MDA and soluble sugar content increased during the treatment;Pro content was increased at first and then reduced;dynamic trends of protective enzyme activity of SOD,POD and CAT were almost similar and they all increased slowly in the early stress stage,and increase rapidly in the process.SOD activity got the maximum value at the 36h,while the CAT and POD got the maximum value at the 24h.These results indicated that both of the osmotic stress and ABA can lead to the accumulation of osmotic substances and activation of protective enzymes in leaves of purple on-heading Chinese cabbage.2 The effects of osmotic stress and ABA on the content of endogenous abscisic acid and gene expression changes related to abscisic acid biosynthesis.The results are as follows:both of osmotic stress and ABA can resulted in accumulation of endogenous abscisic acid,but the accumulation effect was more pronounced under osmotic stress.Protein kinase SnRK(SNF1-related protein kinase)2.6,SnRK2.2,SnRK2.3,NCED(9-cis-epoxycarotenoid dioxygenase)3 and HAB1(homology to ABI1)are important structural or regulatory factors in ABA synthesis and signal transduction.The real-time fluorescence quantitative results illustrated that BcHAB1 plays a role in the negative regulation under osmotic stress.Overal the treatment,relative expression level of BcHAB1 was from high to low.BcNCED3 expression level was gradually upward trend.However,BcSnRK2.6 got slight decrease in 12 h,then increased.As for ABA treatment,the expression level of BcHAB1 and BcNCED3 were increased at the first and then decreased,but still higher than the Oh.The expression level of BcSnRK2.6 was upregulated overall.These results suggest that osmotic stress and ABA treatment resulted in an increase of endogenous ABA is the result of multiple gene interactions,and BcHABl,BcNCED3 and BcSNRK2.6 are more sensitive to osmotic stress and ABA3 Determine the effects of osmotic stress and spraying of ABA on total chlorophyll and carotenoids content,and the expression of 7 genes related to anthocyanins biosynthesis.Liquid chromatograph/mass spectrometer(LCMS)was used to analyze the composition changes under osmotic stress and ABA in purple non-heading Chines cabbage.The results showed that both of the two treatments can result in increased accumulation of anthocyanins and the reduction of the total chlorophyll and carotenoids.In addition,with the time going on and the stress degree increasing,expression levels of BcPAL,BcCHS and BcDFR increased in the first 24 h to 36 h,and then decreased.BcANS and BcCHI increased slowly in the first stress stage and the gradually raised highly,but the change magnitude of BcANS was higher than that of BcCHI.The change trend of BcANS and BcCHI under osmotic stress was the same as anthocyanins change under osmotic stress,suggested that BcANS and BcCHI manybe critical genes in transducting anthocyanin biosynthesis.Exogenous ABA treatment lead to upregulating of BcF3H,BcANS and BcUFGT and these genes got the same change trend with anthocyanin content under exogenous ABA,indicating that BcF3H,BcANS and BcUFGT maybe more sensitive to the exogenous ABA.All of these results suggest that although osmotic stress and ABA can lead to the accumulation of anthocyanins in purple non-heading Chinese cabbage,but the relevant regulatory mechanisms are not the same,further reaserch needs to be done.