Analysis Of Genes Related To Fruit Ripening Of Red Bayberry And Effect Of Morella Cerifera Rootstock On Growing And Fruiting

Morella rubra is a subtropical fruit tree native to China.Its fruit is rich in anthocyanins,antioxidants,vitamin C and aroma substances.Morella cerifera,native to Pennsylvania,USA,is an evergreen shrub that is named as a waxy bayberry because there is a waxed layer on the ripe fruit that can be used as a candle.Waxy bayberry has good adaptation to salt,alkali soils,cold and humidity environment.This study identified and analyzed the MADS-box gene family in red bayberry genome for the first time,identified two genes related to fruit ripening and 1 gene related to fruit colour,which laid the foundation for subsequent genetic research.In addition,we found four genes related to ethylene synthesis and polygalacturonase synthesis respectively,and expression levels were analyzed in four varieties.Finally,we find out the waxy bayberry as the superior rootstock of saline-alkali land.The detailed results as follows:1.Identification of the genome-wide MADS-box gene family of red bayberry and its potential role in fruit ripeningIn this paper,we identified 54 MADS-box genes in the red bayberry genome,and classified them into two types based on phylogenetic analysis.Thirteen Type ?MADS-box genes were divided into three subfamilies and forty-one Type ?MADS-box genes into thirteen subfamilies.A total of 46 MADS-box genes were distributed across eight red bayberry chromosomes,and the other 8 were located on the unmapped scaffolds.Transcriptome analysis suggested that the expressions of most Type ? genes were higher than Type ? among five female tissues.Moreover,26 MADS-box genes expressed during red bayberry fruit development and ten of them showed a high expression.qRT-PCR results validate that the expression of MrMADSO1(MIKCc)and MrMADS41(MIKC*)gradually increased during fruit development and ripening,suggest they may participate in ripening as positive regulator and MrMADS01 was related to fruit color development.2.Expression of firmness,ethylene and related genes during ripening of red bayberryIn this study,four varieties of red bayberry(Biqi,Dongkui,Y2012-145,Xiazhihong)were selected as research materials,and the firmness and ethylene release of the four varieties of red bayberry fruit were measured.The results showed the firmness is reduced dramatically at mature stage,the amount of ethylene released is increasing,but the ethylene release rate is decreasing in fruit ripening.In addition,four PG genes and four ACS genes were found by transcriptome analysis,and the expression levels were further verified by qRT-PCR experiment.It was found that,MrPGl,MrACSl,MrACS2 and MrACS3 were positively correlated with fruit repining,while MrPG2 and MrPG3 were negatively correlated with the maturity of the fruit,MrPG4 and MrACS4 genes are reduced firstly and then increased during fruit development.Therefore,we speculated that these genes play an important role in the fruit ripening process.3.Effect of Morella cerifera rootstock on growth and fruitingIn order to solve the adaptation of bayberry cultivation in the coastal land,this study used grafting technology,waxy bayberry as the rootstock and red bayberry as the scion.The grafting compatibility was studied by comparing the physiological indexes and the cell structure of the graft interface by microscopy.The results showed that the grafting campatibilty was well between the rootstock and the cultivated bayberry,though the 'small-foot'phenomenon was observed,and the grafted tree bear fruit at younger age and fruits were better.