Observation Of Flower Buds Differentiation And Genome-wide Analysis Of The Early Flowering 4(ELF4)Genes In Diospyros Deyangensis

Diospyros.deyangensis represents a new species of Diospyros L.(Ebenaceae).The main characteristic of D.deyangensis is a shorter juvenility period,which can flowering and then bearing fruits after several months of sowing.Therefore,it is a new material to study the underlying mechanism for the flowering time in woody plants.Persimmon has sexuality diversity.The development process of floral buds has been observed in all-female cultivar,monoecious cultivar and all-male species.In order to determine the time of flower organ formation and sex differentiation,we observed the female and male floral buds in different developmental stages in D.deyangensis.The EARLY FLOWERING 4(ELF4)gene has been reported as involved in photoperiod perception,circadian regulation,and flowering development.In Arabidopsis thaliana,significant progress has been made in the study of the mechanism of ELF4 regulating flowering.ELF4 homologs were also found to be involved in flowering regulation in other plants.Identification and analysis of ELF4 gene family members may help to explore the mechanism of flowering in D.deyangensis.The results as follows:1)The floral buds in different developmental stages were observed through paraffin section method and scanning electron microscope.The whole developmental process can be divided into two stages interrupting by dormancy.The bract primordia,sepal primordium and petal primordium are formed in the floral buds at the early stage ranging from June to July.In the later stage of differentiation,from March to May of the following year,floral buds form stamen primordium and carpel primordium.Because the dormancy release time of male floral buds is earlier than that of female floral buds,the formation time of stamen primordium and carpels primordium of male flowers is earlier than that of female flowers.2)The developmental process of the sexual cells in the floral buds was also observed by paraffin section method.In male flowers,a primary sporogenous cells are formed inside the stamens.Sporogenous cells continue to divide and develop until the mature pollen grains are formed.At the base of the carpel primordium in the female flowers,the ovary is formed,and the ovule primordium is produced inside.Then the ovules differentiate and develop,and finally the mature embryo sac is produced.The maturation of pollens and embryo sacs completed basically at the same time.3)In this study,11 ELF4 gene family members in D.deyangensis were characterized through genome-wide analysis.All Dd ELF4 candidates contained a DUF1313 domain,which was conserved in the ELF4 gene family.Gene duplication analysis showed that segmental duplication caused by polyploidization promoted largely gene expansion.4)Similar to other ELF4-ox lines,overexpression of Dd ELF4-8 delayed flowering and increased rosette leaves in Arabidopsis indicating the functional conservation of ELF4 genes in flowering regulation.It is interesting that the overexpression of Dd ELF4-8 was negatively affected At GI and At FT expression levels,which was the likely cause of flowering delay phenotypes.These results strongly suggest that Dd ELF4 genes may involve in flowering development in D.deyangensis.