Physiology And Molecular Mechanism Of 'Sachinoka' White-flesh Mutant Strawberry

Strawberry variety 'Sachinoka' has a good quality,and its white-flesh mutant is sweeter and has more fragrant than 'Sachinoka'.However,the mechanism of the white-flesh mutant is still largely unknown.In this study,the fruits of the four developmental stages of 'Sachinoka'and its white-flesh mutant were used as materials.The contents of soluble sugar,organic acids,polyphenols,and aroma substances were measured.The methylation analysis of anthocyanin related genes were also performed.The expression levels of anthocyanin related genes and aroma related genes were analyzed in order to uncover the formation mechanism of the white-flesh mutant.The main results are as follows:(1)The soluble sugar and organic acid content were determined by high performance liquid chromatography.Glucose,fructose and sucrose content of white-flesh mutant in the red fruit period were significantly higher than 'Sachinoka',while organic acid content were not significantly different,which indicates that the mutant is more sweet in taste.(2)Using high performance liquid chromatography to determine the content of polyphenols,it was found that the content of Pelargonium-3-O-glucoside(Pg3G)and Pelargonium-3-O-rutinoside(Pg3R)in 'Sachinoka' during the red fruit period were significantly higher than the mutant.(3)Methylation sequencing was conducted using 'Sachinoka' and its white-flesh mutant during the turn period,and the methylation level of anthocyanin related genes 4CL2,C4H1,MYB10,PAL1.2 and other genes in 'Sachinoka' and white-flesh mutant have significant differences.(4)Expression analysis of anthocyanin related genes in 'Sachinoka' and its white-flesh mutant,we found that the expressions of 4CL1.1,ANS,CHI,CHS1,DFR,F3 H,TT19,MYB11.2,WD40,GL3 and other genes were higher in 'Sachinoka' than the white-flesh mutant.(5)Amplification of anthocyanin related genes and promoters in 'Sachinoka'' and its white-flesh mutant in the red fruit period,we found that F3 H and MYB1 gene sequences in the two materials are completely identical,and the MYB10 gene sequence identity is 99.95%,The promoter sequence identity of MYB1,MYB10,and MYB111 was 99.55%,99.26%,and99.38%.(6)Using gas chromatography-mass spectrometry to determine the relative content of aroma substances in fruits,it was found that the unique components of white-flesh mutantduring the turn period were Ethyl hexanoate,Ethyl isovalerate and Nerolidolt.The relative content of acids,ethyl esters,acetates and other esters are highest in the two materials during the red period.The relative content of benzene and volatile phenols,ethyl esters,furans and isoprenoids in the mutant are significant improved compared with 'Sachinoka',which may be responsibe for more fragrant in white-fresh mutant than 'Sachinoka'.(7)Expression analysis of aroma substance synthesis pathway genes in 'Sachinoka' and its white-flesh mutant,we found that CAD1,CAD2,ACX1,ACX2,PED1 a,MFP2 in the?-oxidation pathway and MMDH1,PMDH1,LOX6,Fv H4-12460 in the LOX pathway have higher expression levels in mutant.