Dynamic Development Of Flower And Screening Of Self-Incompatibility Genes In Pitaya

In recent years,the market scale of pitaya is gradually expanding and the planting area is increasing in China.As a nascent tropical fruit,pitaya has high nutritional value for consumers and provides good economic returns for growers.In the process of planting pitaya fruit,the artificial pollination varieties were replaced by self-pollinated ones.In the early days,the self-incompatible pitaya required collecting exogenous pollen for artificial pollination at night,which greatly limited the development of the pitaya industry.Now,the main varieties of pitaya in production have overcome the problem of self-incompatibility and are basically self-pollinated varieties.To explore the self-incompatibility mechanism of pitaya,this research is divided into two aspects.On the one hand,the dynamic development process of pitaya flowers was studied from morphology by using "Jindu No.1" pitaya as observation material.By comparing the flower structure,pollen quantity and pollen activity of self-incompatible pitayas and self-compatible pitayas,the self-incompatibility mechanism of pitaya was investigated in morphology.On the other hand,physiological indicators and gene expression before and after pollination were compared between the two groups,including soluble sugar and soluble protein content,as well as gene expression of self-incompatibility gene(S-locus receptor kinase).Furthermore,interaction protein for S-locus receptor kinase was screened by yeast two-hybrid technique,which explored the mechanism of self-incompatibility of pitaya at the molecular level.The researchs are as follows:1)Pitaya flowers take about 20 days to fully develop in the summer in Hainan.The dynamic growth curve of pitaya flowers showed an increasing trend,and it grew rapidly from day 14 to day 16.2)The distance between stigma and anther for the self-incompatible pitayas was significantly higher than that of self-compatibility pitayas.The pollen quantity and pollen activity of self-incompatible pitayas was significantly lower than that of self-compatibility pitayas.3)The soluble proteins and soluble sugars of style and stigma were significantly changed in the course of pollination of pitaya.The content of soluble protein and soluble sugar in the style and stigma of self-incompatible pitayas rose in a short time after pollination,which was significantly higher than that of self-compatible pitayas.After 12 hours of pollination,the soluble sugar and soluble protein contents of self-incompatible pitayas and self-compatible pitayas decreased significantly.The physiological changes in the ovary occurred after 12 hours of pollination.The contents of soluble sugar and soluble protein of self-compatible pitayas increased,which was significantly higher than that of self-incompatible pitayas.4)Eight annotated genes were selected from transcriptome data.They are Hp SRK1(CL1432.Contig1?All),Hp SRK2(Unigene26840?All),Hp SRK3(Unigene9281?All),Hp SRK4(Unigene4596?All),Hp SRK5(CL1997.Contig5?All),Hp SRK6(Unigene15993?All),Hp SRK7(CL1997.Contig2?All),Hp SRK8(Unigene7302?All).The specific expression of Hp SRK3(Unigene9281?All)and Hp SRK4(Unigene4596?All)genes on stigma and style was confirmed by tissue specific screening.Through subcellular localization experiments for Hp SRK3(Unigene9281?All)gene,it was confirmed that Hp SRK3 is located on the cell membrane related to the self-incompatibility reaction.5)The cytochrome bc1 complex,an interaction protein for Hp SRK3,was screened by yeast two-hybrid and preliminarily verified in yeast.This study provides a theoretical basis for further research on the self-incompatibility mechanism of pitaya fruit.