Effect Of Seed Soaked And Sprayed With BTH On Postharvest Wound Healing,Fruit Storage And Plant Growth Of Muskmelons

Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester(BTH)is the first artificially synthesized and commercialized elicitor named Bion? or Actigard? and can induce field and postharvest disease resistance of a variety of crops.However,the effects of the preharvest treatment on wound healing and storage of harvested muskmelon and field growth have not been reported.In this study,the muskmelon 'cv.Manao' seeds were soaked with 100 mg/L BTH and the plants were sprayed with BTH during fruit development.The effect of BTH treatment the wound healing of postharvest fruit was evaluated and some mechanisms were explored.The storage ability of treated fruits and growth of treated plants were observed.The results showed that as follow:1.Preharvest BTH treatment effectively reduced the weight loss of artificially wounded fruit and disease index of inoculated fruit with Trichothecium roseum during healing.In addition,BTH treatments promoted the accumulation of suberin polyphenol,subrein polyester and lignin at the wound sites of fruit,among which the combined treatment showed the best effect,followed by soaking and spraying treatments.2.Preharvest BTH treatment enhanced the activity of phenylalanine ammonialyase,cinnamic acid hydroxylase,4-coumaroyl-coenzyme A-ligase,cinnamyl alcohol dehydrogenase,cinnamoyl-Co A reductase and polyphenol oxidase.In addition,the treatment also effectively increased the content of total phenols,flavonoids,lignin,endogenous salicylic acid,cinnamic,caffeic,ferulic and p-coumaric acids at the wound sites of fruit during healing.3.Preharvest BTH treatment elicited the activities of long chain acyl-Co A synthase,cytochrome P450 monooxygennase,3-Ketoacyl-Co A synthase,fatty acylCo A reductase,glycerol-3-phosphate acyltransferase at the wound sites of fruit during healing.Moreover,BTH treatment promoted the activities of ferulyltransferase and ATP-binding cassette transporters G at the wound sites of fruit during healing.3.BTH treatment reduced cell membrane permeability and malondialdehyde content,increased the content of superoxide anion and hydrogen peroxide at the wound sites of fruit during healing.Meanwhile,the treatment increased the activity of NADPH oxidases,superoxide dismutase,catalase,peroxidase,ascorbate peroxidase,glutathione reductase,dehydroascorbate reductase and monodehydroascorbate reductase.In addition,BTH treatment effectively increased the content of ascorbic acid and reduced glutathione.4.BTH treatment significantly reduced the weight loss rate,decay index,the lesion diameter of fruits inoculated with T.roseum and natural incidence of muskmelon during storage.In addition,the treatment also inhibited fruit respiratory rate and total soluble solid content,increased the brightness of the peel,postpone fruit yellowing,delayed fruit softening.5.Soaked with BTH increased the germination energy and germination index of seeds,and promoted seedling thickness and stem diameter,but had no effect on main root length.In addition,BTH sprays promoted the stem diameter during growth and increased single fruit weight at harvest.It is suggested that preharvest BTH treatments promote wound healing of harvested muskmelons.The promotion mechanism by BTH involves in inducing the synthesis of endogenous salicylic acid and reactive oxygen species,eliciting phenylpropanoids and fatty acid metabolism at the wound sites of fruit.Moreover,preharvest BTH treatments inhibit the ripening of fruit and reduce weight loss as well as disease incidence of fruit during storage.Soaked with BTH promoted seed germination and seedling growth,BTH sprays on plants also increase single fruit weight at harvest.