Research On Physiological Indexes And Differentially Protein Expression Of Hami Melon Under Cold Stress

Hami melon is main production cash crop in Xinjiang,because of the concentration of its harvest time,high temperature,high rate of decay,causing huge losses to farmers.Low temperature storage is an important measure to reduce the loss ratio of Hami melon during storage and transportation.However,Hami melon is a subtropical fruit,which is sensitive to temperature and more likely to have chilling injury,leads to reducing commodity value of the fruit.When facing with cold stress,Hami melon will starts some defense-related proteins automatically,thus delay the occurrence of chilling injury.Object: In his paper,symptoms of Hami melon’s chilling injury and impact of changes in enzyme activity on Hami melon’s cold tolerance were learnt via the determination of physiological index for Hami melon at different storage temperature.Moreover,analysed the change in protein of Hami melon before and after cold stress via Bioinformatics,speculated the relationship between differentially expressed proteins and cold resistance of Hami melon.Not only provided the basis for the study of the molecular mechanisms of Hami melon response to abiotic stress,but also provided a theoretical basis for the various forms of Hami melon storageMethods: Quantitative analysis of protein using IBT technology;using bioinformatics analysis of differentially expressed protein of types,quantity and function,and identification defense-related proteins.The response reaction mechanism of Hami melon to cold stress was revealed;By ELISA method for determination of Postharvest Hami melon that the activitieschange of the fatty acid desaturase(FAD),the lipoxygenase(LOX)and the adenosine triphosphatase(ATPase)under different temperature storage.Results and Conclusion:(1)Determination of physiological and biochemical indexes of Hami melon found the melon was highly vulnerable to the chilling injury at 3℃ and 0.5℃,but it maintained a higher activities of the FAD and the ATPase,inhibited the increase of the LOX activity.In spite of no chilling injury at 21℃,the weight loss rate and the rot rate was relatively high.(2)Quantitative analysis of Hami melon protein were made via IBT technology,5291 proteins were identified in Hami melon tissues,annotations were made on 49 GO-terms by GO annotation.Compared with the COG database,a total of 4582 proteins were annotated,R class general function prediction predicted the most proteins,314 proteins are related to the signal transduction mechanisms and 21 proteins are related to defense mechanisms on cold stress.109 function unknown proteins were founded,which may be new protein.Compared with the KEEG database,4492 proteins were mapped to 134 metabolic pathway,metabolic pathway has the highest protein enrichment than any other pathway.(3)In the different stages of cold stress,the identified differential proteins were different.Compared with the day 0,it is found that at the same storage temperature,the number of differential protein increased as storage time went on.On 24 th day,the most number of differential proteins were identified with a number of 940 at 21℃,which 496 up-regulated,444 down-regulated,while the least number of differential proteins were identified at 0.5℃,which 138 up-regulated,193 down-regulated.Cold stress-related differential proteins with large differential expression are LRR receptor-like serine/threonine-protein kinaseFLS2,ATP-dependent zinc metalloprotease FTSH、peroxidase 2-like,heat shock protein,60 S ribosomal protein L34,beta-glucosidase 12-like etc.Some unknown proteins such as uncharacterized protein LOC103492216,uncharacterized protein LOC103500944,etc.were also founded.Cluster analysis of differential proteins were made,23 common expression difference differential proteins were obtained,which mainly involved in photosynthesis,energy metabolism and stress response process.(4)GO significant enrichment analysis on differential proteins showed high differential protein enrichment involved GO-terms are carbohydrates,structural molecule activity,ellular macromolecular complex assembly,photosynthesis,response to abiotic stimulus.Pathway significantly enriched analysis of differentially expressed proteins found that the large number of different protein enrichment of metabolic pathways,biosynthesis of secondary metabolites,protein processing in endoplasmic reticulum,Plant-pathogen interaction and may be involved in these pathways the difference in protein Hami melon response to cold stress,and their functions,may be a regulated,regulation can also be negative,needs to be further verfied.