The Fresh-keeping Effects Of Hot Air Treatment On Cut Gerbera Flowers And Their Transcriptomic Analysis

Heat treatment(usually hot water and hot air short time treatment),as a fresh horticultural products postharvest preservation technology,its research and application mainly concentrated on the fruit and vegetable postharvest treatment and preservation,and there were only sporadic reports on heat treatment of the cut flowers and was lack of in-depth systematic research.In this thesis,the author firstly studied and established the method of hot air treatment for cut gerbera(Gerbera jamesonii)’Real’ and ’Crossfire’ flowers,and then focused on their effects of the ornamental quality,vase life,related physiological indexes and the content of microbes at the stem-ends.Finally,the expression pattern of some important genes in petals of cut gerbera ’Real’ flowers was analyzed based on transcriptome sequencing.The main findings were as follows:1.To study and explore the feasibility and basic method of hot air treatment for cut flowers,the hot air treatment and hot water treatment were compared with cut gerbera ’Real’ and ’Crossfire’ flowers.The results showed that:(1)Appropriate hot air treatment(43℃for 90 min)had obvious fresh-keeping effects,especially in prolonging the vas life,improving ornamental quality and maintaining the fresh weight of cut gerbera ’Real’ flowers;(2)43℃ for 90 min hot air treatment also had significant fresh-keeping effects on cut gerbera ’Crossfire’ flowers;(3)The appropriate hot water treatment(38℃ for 15 min or 46℃ for 5 min)also had significant fresh-keeping effects on cut gerbera ’Real’ flowers(38℃ for 15 min was the best treatment).In comparison,hot air treatment was superior to hot water treatment in the preservation of cut gerbera ’Real’ flowers.2.Based on the established method of hot air treatment,the effect of hot air treatment(43℃ for 90 min)on related physiological indexes and the content of microbes at the stem-ends were further studied.The result showed that:(1)Hot air treatment(43℃ for 90 min)could helps maintain anthocyanin content in petal of the cut gerbera ’Real’ flowers is relatively stable,and the anthocyanin content in petal on the 5th and 7th day were effectively higher than control.(2)The water content in petal of cut gerbera ’Real’ flowers after hot air treatment at once was lower than control.However,the water content in petal of cut gerbera ’Real’ flowers in the treatment group increased more quickly than the control during the whole vase period,so that the water content in petal in the treatment group on the 9th day was higher than the control.(3)The observational results of Scanning Electron Microscopy show that,hot air treatment(43℃ for 90 min)could reduce the mutiply of microorganism in stem-ends of cut gerbera ’Real’ flowers,and reduce the degree of microbial coverage in the base of the stem.3.There were 76,679 Unigenes and 35,776 annotations in the results of RNA-seq of petals on cut gerbera ’Real’ flowers.Through the screening of the difference genes between the control and the hot air treatment group,it was found that the hot air treatment could stimulate the expression of HSP90,HSP70 and HSFs in the petals on cut gerbera flowers,namely,43℃ for 90 min hot air treatment could enhance heat resistance and resistance of cut gerbera flowers.Additionally,hot air treatment can inhibit the expression of more genes related to anthocyanin synthesis,and stimulated the high expression of a large number of receptor-like kinase genes,abscisic acid signal transduction genes and ethylene signal transduction genes,etc.