Functional Studies On Dendrobium Catenatum PRC1 Complex

Dendrobium catenatum is a perennial herb of the Orchidaceae family and is mainly used as a valuable Chinese herbal medicine and has remarkably ornamental,medicinal and theoretical values.PRC1(Polycomb Repressive Complex1)is composed of several key PcG(Polycomb Group)proteins,playing important roles in cell fate transition and individual growth and development.In recent 20 years,many studies have revealed the important function of PRC1 in model plant Arabidopsis,and the function of D.catenatum PRC1 complex maintains unclear.In this study,the functional conservation and divergence of PRC1 complex components in Arabidopsis and D.catenatum were investigated from five aspects,including phylogeny,expression pattern and stress response,protein interaction network,subcellular localization and heterogenous transformation.It is expected to lay a foundation for the further research on plant development mechanism and provide clues for the genetic breeding of D.catenatum.The main results are as follows:(1)D.catenatum PRC1 subunits are highly similar to the corresponding Arabidopsis homologous in terms of gene structure and protein domain composition.Results of protein sequence alignment showed that RING1 in PRC1 complex was conserved in the evolution of monocotyledonous plants,while BMI1,LHP1 and EMF1 diverged greatly,among which LHP1 was the most diverged.(2)Quantitative PCR and in situ hybridization showed that the expression of four PRC1 genes of D.catenatum was mainly concentrated in the young tissues of the plant,and there were differences in the expression of different PRC1 genes.(3)D.catenatum PRC1 gene expression was affected by environmental stress factors,and different genes had different response modes under different environmental stress.(4)The interaction relationships among D.catenatum DcPRC1 subunits were similar to those in Arabidopsis,suggesting composition of PRC1 subunits is evolutionarily conserved in plant.(5)35S::DcLHP1-GFP transformation in Arabidopsis showed DcLHP1 is located in the nucleus;transgenic plant displayed significant early flowering,in which about 20% phenocopy Atlhp1.Preliminary analysis shows that the phenotype of transgenic plants was unrelated to the expression of AtLHP1,which was speculated to be caused by the over expression of DcLHP1 protein competitively binding AtLHP1 target sites of in the nucleus.