Functional Analysis Of The Ethylene Biosynthesis And Signaling Pathway Related Genes During The Ripening Of Five Species Of Fruit Crops

Fruit ripening was a complex,genetically programmed process that culminated in dramatic changes in color,texture,flavor,and aroma of the fruit flesh.Ethylene regulated many aspects of the plant life cycle,it was biologically active in trace amounts and its effects were of great commercial importance.Ethylene mediated regulation of ripening at various levels,which was related with ethylene biosynthesis and signaling.Regulating the ethylene biosynthesis related genes could effectively inhibit the ethylene production,and controls the fruit mature process.So based on the ethylene biosynthesis mechanism research,the outreach of ethylene signal transduction pathways in fruit ripening could also provide new scientific basis for further research.By using bioinformatics methods,we predicted the ethylene biosynthesis and signaling pathway related genes in non-climacteric fruits(grape and strawberry)and climacteric fruits(apple,peach and pear)using the Arabidopsis thaliana ethylene biosynthesis and signaling pathway related genes as probes,and verified these predicted genes by gene expression.We verified 23 genes in grape,23 genes in strawberry,18 genes in apple,27 genes in pear and 16 genes in peach.The result showed that the transcript amounts of different members in the same gene family will be different in the expression and function of fruit ripening process.The results showed that ethylene biosynthesis and signaling pathway related genes exist in both non-climacteric fruit and climacteric fruit.Non-climacteric was able to produce significant levels of ethylene during fruit development,but not to the same extent as climacteric fruits.However,the number of ethylene biosynthesis and signaling pathway related genes and their expression patterns in these two kinds of fruit crops were different,which may lead to their different response patterns to ethylene.The total EST number of the ethylene biosynthesis and signaling pathway related genes in grape and apple were more than that in peach.The ratios of the EST number in fruit to those in all the other tissues of the related genes in peach were more than that in apple and grape.We compared the amino acid sequences of VvACO1 and PpACO1and found 53 amino acid changes,including 32 same types of amino acid changes and 21 different types of amino acid changes.To further study whether the changes of these amino acids determined the functions of the genes or not,the key enzyme gene ACO and the downstream element of ethylene synthesis pathway in grape and peach were carried out using transient expression.The results showed that the transient expression of VvACO1 and PpACO1 could lead to the up regulation of ACO1 in tomato and promote the ripening of fruits.But the promotion effect of PpACO1 was stronger than that of VvACO1.By contrast,the silence of VvACO1and PpACO1 could interfere the expression of LeACO1 in tomato and delay the ripening of fruits.The same phenomenon could be observed in VvERF and PpEIN3,as the transient expression of VvERF and PpEIN3 could lead to the up regulation of LeACO1 in tomato,and the silence of VvERF and PpEIN3 could interfere the expression of LeACO1 in tomato and delay the ripening of fruits.Endogenous hormones played important roles in the development of grape.To further understanding the role of ethylene and other hormone in grape growing development process,we analyzed the expression and regulation mechanisms of the key endogenous hormone genes during the first growth period(40 ds after blooming),veraison period(65 ds after blooming)and the mature period(90 ds after blooming)in the whole genome level by RNA-seq.The differentially expressed genes(DEGs)were further verified by qRTPCR.The results showed that for each sample,more than 64%of the reads can be aligned to the reference genome.The DEGs of DAF65/DAF40 were 5,620,including 957 genes up-regulated and 4,663 up-regulated;the DEGs of DAF90/DAF40 were 5,196,including 1,340 genes up-regulated and 3856 up-regulated;the DEGs of DAF90/DAF65 were 3,381,including 2,035genes up-regulated and 1,346 up-regulated.The GO and Pathway analysis of the DEGs indicted that there were 8 hormones involved in fruit development process.Most of the hormones related DEGs were the IAA signaling pathway related genes,and then were ABA,JA and ETH.And the results indicated that the DEGs genes played an important regulatory role in fruit development.