Study On Red Cold-resistance Breeding And Difference Of Flower Color Phenotype Between Parents And Hybrids Of Prunus Mume

Prunus mume has a long history of cultivation and application in China.It is deeply loved by people because of its excellent ornamental characteristics and profound flower culture.In order to enrich the flower color of cold-resistant cultivars in northern areas,this study took the breeding of red cold-resistant cultivars as the breeding goal,and selected P.mume‘Dan Fenghou’,P.mume‘Meiren’as female.The experiment explored the cross compatibility between different parents,the seed setting rate,and the method of hybrid F1.P.mume‘Meiren’had problems of difficult to break seed dormancy and extremely low germination rate.The rapid seedling system of P.mume‘Meiren’was established by measuring its seed germination characteristics.were used to analyze the flower color phenotype,anthocyanin content,and the expression patterns of structural genes and transcription factors related to anthocyanin synthesis according to the difference in flower color phenotype between hybrids and parents,so as to preliminarily explore the molecular mechanism for the formation of flower color phenotype difference between hybrids and parents.The main conclusions of this paper were as follows:（1）A total of 35 hybrid combinations with 6468 pollinations were designed in the hybrid experiment,Finally,66 hybrid seedlings（57 interspecific hybrids and 9 distant hybrids）were harvested.Among them,15 were identified as early hybrids,and 11 were identified as true hybrids.The compatibility of hybrid combinations P.mume‘Dan Fenghou’×P.mume‘Fenbi Zhaobo’,P.mume‘Meiren’×P.mume‘Da Gongfen’and P.mume‘Dan Fenghou’×P.persica‘Baihua Shanbi’was good,while the compatibility of distant hybrid combinations P.mume‘Dan Fenghou’×P.tomentosa,P.mume‘Meiren’with different peach cultivars was poor,showing unfruitful.The application of 100 mg/L and 50 mg/L GA₃on P.mume‘Dan Fenghou’×P.persica‘Baihua Shanbi’and P.mume‘Dan Fenghou’×P.triloba could effectively improve the seed setting rate of distant hybridization.（2）The seed germination characteristics of female parent P.mume‘Meiren’were determined.The results showed that the seed water absorption,seed coat permeability and water content were good,and the seed viability was low.However,the endocarp and seed coat containing endogenous inhibitors may be the main reason for the seed dormancy of P.mume‘Meiren’,and the ordinary low temperature sand storage cannot effectively relieve the effect of endogenous inhibitors on its germination.（3）The rapid seedling system of P.mume‘Meiren’was established based on seed germination characteristics of P.mume‘Meiren’.For the seeds stored at 4°C for a certain time,they were soaked in water for 24h,then soaked in 300 mg/L gibberellin for 6h,and stored at 4°C for 90d.After removing the endocarp,the highest seedling rate was 50%,and the seedling period was about 250d.For fresh fruits,the internal and external pericarps and seed coats were directly removed.The embryos containing cotyledons were stored in high-temperature sterilized river sand at 4°C for 90d,and then the seedling rate was 12%,and the seedling period was 110d.1/2 WPM+0.2 mg/L 6-BA+1.0 g/L AC was the optimum medium for embryo culture of P.mume‘Meiren’.The seedling rate was 56.67%and the seedling period was about 120d.（4）The determination of flower color phenotype and anthocyanin content showed that the deeper color of the hybrids than that of the parent was related to the accumulation of anthocyanin,that is,the total anthocyanin content in petals was positively correlated with the red degree of flower color.The total anthocyanin content of the hybrids and the parent showed a decreasing-increasing-decreasing trend during the flower development period.（5）The results of qRT-PCR showed that PmCHS,PmF3’H,PmDFR and PmANS might be the downstream target genes of Pm MYB1 and positively regulated by Pm MYB1.Combined with the transcription characteristics of anthocyanin synthesis-related genes in different cultivars at profuse flowering stage,it was preliminarily considered that the higher color redness of hybrids than that of parents might be related to the high expression of Pm MYB1,which increased the expression levels of genes Pm DFR in anthocyanin synthesis.