Regulation Technology Of Glucosinolate And Isothiocyanate Accumulation In Cabbage Sprouts(Brassica Oleracea VAR.Capitata)

The present study aimed at investigating the accumulation and regulation techniques of GLs and ITCs and in germinated cabbage sprouts?cultivar Xialv 50?treated with heat stress,hypoxia,heat plus hypoxia stress,abscisic acid,jasmonic acid;and the changes of physiological and biochemical during the germination after these treatment also measured.The aim of this study was to provide scientific guidance and theoretical basis on the enrichment of GLs and ITCs,and the development of rich ITCs cabbage sprouts.The main results were listed as following:1.After heat treatment,the growth of cabbage sprouts was inhibited;the sprouts length and weight were both lower than control;the electrolyte leakage and the level of ascorbic acid,total phenolic and malondialdehyde?MDA?were all higher than the control.At 50 and 60 ? under heat stress,the total and aliphatic GLs and MYR activity were also higher than the control heat temperature;the ITC formation was at a higher level;in this case the GLs and ITCs were inriched in cabbage sprouts.The electrolyte leakage and MDA content increased and the restrained degree of sprout growth aggravated with the increase of heat stress temperature.In cabbage sprouts treated at 60 ?,the ITC precursor GLs content,ITC formation and MYR activity were the highest among the three heat sress temperature?40,50,60 ??,as well as the content of total phenolic and ascorbic acid.2.The reduce of O₂ concentration had little effects on the growth of cabbage sprouts,but it could significantly increase the GL content and ITCs formation.8%O₂ concentration was most conducive to the inrichment of GLs and ITCs in cabbage sprouts.With O₂ concentration unchanged,the increase of CO₂ concentration signicicantly inhibited the growth of cabbage sprouts.1%CO₂ concentration was most conducive to the inrichment of GLs and ITCs in cabbage sprouts among the three CO₂ concentrations.Therefore,8%and 1%were chosen as the optimal O₂ and CO₂ concentration,respectively.3.The content of total GLs,total phenolic and ascorbic acid and ITC formation in cabbage cotyledon were significant higher than those in cabbage hypocotyl and roots,while the MYR activity in hypocotyl was significant higher than other two organs.Heat stress treatment significantly increased the level of total GLs,totoal phenolic,ascorbic aicd and the ITC formation in cabbage sprouts and cotyledon;and increased the MYR activity in hypocotyl compared with the control,but there was no significant different with hypoxia treatment;meanwhile,there was no significant different effect on ascorbic acid and even lower.The possible reason was that heat treatment influenced the related biosynthesis enzyme of ascorbic acid in cabbage cotyledon.The effect of heat plus hypoxia treatment on GLs,MYR,ITCs,ascorbic acid and total phenolics was not the synergistic effect of heat and hypoxia stresses.4.ABA inhibited the growth of the cabbage sprouts and reduced its biomass.The GL content,ITC formation and MYR activity in cabbage sprouts significantly increased after ABA treatment;the ITC formation in 25?75 ?M ABA treated sprouts were 1.96?3.70-fold of those in control.In cabbage sprouts from day 1 to day 5,50 ?M ABA effectively slowed down the declining rate of GLs and total phenolic content,improved the MYR activity and ascorbic acid content,and sprout ITCs formation in cabbage sprouts increasing rapidly from day 3 to day 5;in addition,as a major edible parts of cabbage sprouts,the cotyledon and hypocotyl contained the highest GLs,total phenolics and ascorbic acid content,as well as ITC formation.The health promoting compouds mentioned above in cabbage sprouts,cotyledon and hypocotyl all significantly increased after ABA treatment.The results indicated that ABA could regulate the physiological and biochemical changes of cabbage sprouts during the germination,as a result the health promoting compounds accumulated.5.JA significantly inhibited the growth of the cabbage sprouts and reduced its biomass.However,it effectively increased the GLs content,especially indole GLs Glucobrassici?GBC?and Neoglucobrassicin?NEO?.Under JA treatment,only 100 ?M JA increased the ITC formation in cabbage seedlings by increasing the MYR activity.The study also found that the cotyledon of the control and JA treatment contained the highest content of total GLs,aromatic GLs and indole GLs especially GBC and NEO,as well as the ITC formation.The spraying of exogenous JA on the cabbage sprouts during the germination could effectively restrain the decrease of GLs especially the indole GLs GBC and NEO which caused by the germination;JA aslo increased the activity of MYR and reduced the decline of ITC formation during germination.