Analysis Of Differentially Expressed Genes During The Pollen Chamber Formation In Ginkgo Biloba L. Ovules

Previously,it has been demonstrated that pollen chamber formation(PCF)in Ginkgo biloba ovules is a process of programmed cell death(PCD)within the nucellar cells at the micropylar end.However,the signal triggering the cascades of the programmed events in these nucellar cells remains unexplored.In this study,a transcriptomic strategy was employed to unravel the mechanism underlying the nucellar PCD via the comparative profiles of RNA-seq between pre-PCF and post-PCF ovules.The main findings are listed as follows:1.A total of 5599 differentially expressed genes(DEGs)with significance was identified from G.biloba ovules and classified into three main categories of GO annotation,including 17 biological processes,15 cellular components and 17 molecular functions.KEGG analysis showed that 72 DEGs were enriched in "Plant hormone signal transduction".2.Furthermore,99 DEGs were found to be associated with the PCD process,including the genes involved in ethylene signaling pathway,PCD initiation,and PCD execution.Such as EIN3/EILs,MPK 6,CYTC-1,CAM,Cysteine Proteinase,Autophagy-related Proteins and VPE.3.The GbEIN3/EIL family genes in G.biloba were cloned and analyzed with bioinformatics methods.It was found that GbEIN3/EIL members had a high conservation with their homologs from other species.Fluorescence qPCR results showed that the expression of GbEILl and GbEIL2 ranged from the first to third stages of PCF was in a trend of increase,whereas their expression at the fourth stage became decreased,which was consistent with the results from the transcriptome sequencing.