Function Analysis Of Two PYL Family,Endosperm-specificic Promoters/genes In Rice

In previous work,we searched for endosperm-specific expressed genes from public rice database.We have identified an Oslatex-1 gene(for Latex-related),whose promoter possessed highly endosperm-specific expression activity in rice.In this study,we identified a new homologous gene of Oslatex-1,named as Oslatex-2.Sequences analysis revealed that Oslatex-1 and Oslatex-2 shared homology with 95%.Data from public database suggested that both Oslatex-1 and Oslatex-2 specifically expressed in rice endosperm,but not in roots,stems,leaves,spikelets,embryos.The upstream approximate 2 kb promoters of OsLatex-1 and OsLatex-2 were cloned and fused to drive a gus reporter gene in transgenic rice plants.The results of GUS histochemical staining and quantitative GUS activity assay showed that both pOsLatex-1 and pOsLatex-2 controlled gene expression specifically in rice endosperm.The functional elements of pOsLatex-1 were analyzed by 5'-truncation approach combining with bioinformatic prediction with plantcare and PLACE database.the results showed that the activity of Gus enzyme decreased significantly when the range-1055 to-845 containing Prolamin domain,or the-300core box was deleted.The conserved sequence fragment of-325 to-173 which contained 02site and GCN4 was found to be necessary for endosperm-specific expression pattern.Furthemore,pOsLatex-1,pOsLatex-2 transcription start sites were determined based on 5'-RACE experiments.Sequence prediction suggested that OsLatex-1,and OsLatex-2 are putative rice ABA receptor genes belonging to PYR/PYL/RCAR family,which may be involved in the ABA pathway.To study the functions of OsLatex-1 and OsLatex-2,the over-expression and RNAi vectors were constructed and used to generate stable transgenic rice plants.Preliminary results suggested that OsLatex-1 and OsLatex-2 may be involved in root development response to ABA treatment.