Genome-wide Identification Of Imprinted Genes And Association Mapping With DNA Methylation Modification In Sunflower Endosperm

Gene imprinting is an epigenetic phenomenon based on the expression of a parent's single allele.This phenomenon mainly occurs in hundreds of genes in plant endosperm,but these genes often play a very important role in biological development such as seed morphogenesis,dormancy,and post-zygotic isolation.Up to now,only the endosperm of Arabidopsis,rice,corn,sorghum,castor,shepherd's purse,Arabidopsis thaliana,wheat,and rape have completed the identification of whole genome imprinted genes.Therefore,the identification of imprinted genes in plants is still very limited,especially in dicots.Species that have completed imprinted gene identification belong to the Brassicaceae family.Sunflower(Helianthus annuus L.)is one of the most important oil crops in the world and belongs to the Asteraceae family with the largest number of species in angiosperms.In this study,the imprinted genes in sunflower endosperm were identified,and the methylation level was analyzed.Therefore,this study identified the imprinted genes in sunflower endosperm and analyzed their methylation levels.We crossed the edible sunflower(SA1,SA2)and the oil sunflower(YA1,YA2)to obtain the F1 endosperm of the reciprocal cross with SA1 and YA1,SA2 and YA2 as parents,and constructed RNA-seq library and sequencing.This study found that:(1)76,065 SNPs between SA1 and YA1 and 62,420 SNPs between SA2 and YA2 were identified.(2)According to the differential expression of parental alleles in the endosperm of reciprocal crosses,480 imprinted genes were identified in the SY1 and YS1 combinations;474 imprinted genes were identified in the SY2 and YS2 combinations.(3)Approximately 69% of MEGs and 29.45% of PEGs expressed specificity in endosperm.(4)Through homology comparison with imprinted genes in other 6 plants,we found that 54.30%?75.40% of imprinted genes in other plants have homologous imprinted genes in sunflower.(5)Through the methylation analysis of the epidermal and endosperm of imprinted genes,it is found that DNA methylation is likely to participate in the regulation of the differential expression of imprinted gene alleles.The above results will help us understand the mechanism of sunflower endosperm development and the conservation of plant imprinting genes.