Lignin Accumulation And MYB46 Gene Expression Of Endocarp In Almond Cultivars ‘Zhipi’ And ‘Changshitou’

Using a thin-shell cultivar of ‘Zhipi’ and a thick-shell cultivar ‘Changshitou’ almond as test material,histochemistry analysed changes regulation of tissue structure during the development of endocarp in almond,physiological determinated dynamic difference of endocarp relative principal components containing substances,cloned MYB46 gene of lignin synthesis related in two cultivars of endocarp in almond,analysed sequence feature and predicted its biological functions,compared and analysed expression patterns of two genes,proved accumulation characters of lignin in almondand effect of lignin synthesis related MYB46 gene during accumulation of lignin in endocarp,and lay the foundation for genetic improvement of almond.The main results are as follows:(1)Cell diameter,cell layers of ‘Changshitou’ almond endocarp were on the rise,and significantly higher than that of ‘Zhipi’ during development process of endocarp in almond.‘Changshitou’ endocarp was dyed range of phloroglucin dye liquor was more than ‘Zhipi’,Endocarp in ‘Zhipi’ and in ‘Changshitou’ were both continuing to lignificate,theirs style were respectively from inside to the outside and both sides to middle.Whole endocarp development process in ‘Zhipi’ respectively lasted about 75 days and 90 days.Bound occurrence of ‘Changshitou’ between mesocarp and endocarp was earlier 15 days than ‘Zhipi’,and endocarp development formation in ‘Changshitou’ was later 15 days than ‘Zhipi’.the development of cells in the endocarp of almond can be divided into three stages,the development stage of endocarp,the rapid development stage of endosperm,and the formation of endocarp,The development of endocarp cells in almond and the thickening of the secondary cell wall accompanied accumulation of lignin.(2)Changing rule of lignin and cellulose content of ‘Zhipi’ and‘Changshitou’ almonds endocarp both showed a rising trend.polyphenol content showed an decline trend.‘Changshitou’ endocarp of lignin and cellulose content respectively days after flowering 55 and 40 is always higher than that of ‘Zhipi’,but the polyphenol content is always lower than ‘Zhipi’;lignin and cellulose content was positive correlation relation,and negative correlation relation with the content of polyphenol.PAL,CAD,C4 H,PPO and POD activity of two almond cultivars were in the same trend,but the peak time and size of the activity were different.Thick shell ‘Changshitou’ almond higher PAL,CAD,C4 H,PPO,POD activity and a lot of precursors of lignin synthesis promoted accumulation lignin,lignifications degree was higher ‘Zhipi’.(3)Cloned MYB46 gene from ‘Zhipi’ and ‘Changshitou’ named Ac MYB46-z and Ac MYB46-c,the full-length of two genes were 1 380 bp,ORF was 1 017 bp,which encoding 338 amino acids.The molecular weight of protein were 37.36 and 38.77 k Da,MYB46 protein sequences of two cultivars both were water soluble,non mixed type instability secretory protein.Endocarp of two genes were expressed at different developmental stages,and the relative expression of MYB46 genes was relatively high during the rapid accumulation of lignin,the relative expression level of Ac MYB46-z was significantly lower than that of Ac MYB46-c after the relative expression reached a peak.MYB46 gene participated in the regulation of the metabolism of lignin of endocarp in almond.