PMC

Functional categories of the 12,311 genes common to three Brassicaceae species. GO terms were assigned and sorted for 12,311 expressed genes common to three Brassicaceae species.

Conservation of papilla-expressed genes in Brassicaceae. Venn diagram for the number of genes in papilla cells from A. thaliana, A. halleri and B. rapa.

Comparison of transcriptome data sets from papilla cells, stamen, leaf and flower in A. thaliana. (A) Venn diagram for the number of genes expressed in papilla cells, stamen and leaf. Expression data for stamen and leaf are from . (B). Venn diagram for the number of genes expressed in papilla cells and flowers. Expression data for flowers are from .

Distribution of TFs and receptor-like kinases (RLKs) in the 12,311 genes common to three Brassicaceae species. TFs were assigned by the Database Arabidopsis Transcription Factors (DATF: http://datf.cbi.pku.edu.cn/) for the 12,311 common genes. RLKs were identified and categorized among genes that have GO terms ‘plasma membrane’ within cellular components.

Confirmation of gene expression patterns by in situ hybridization. The pistils for in situ hybridization were collected 1 d before anthesis. Both antisense and sense probes were synthesized using a T7/SP6 digoxigenin RNA labeling kit. Insets show the signal area in papilla cells at high magnification. (A) AT1G09690, (B) AT1G53130, (C) AT2G41430, (D) Bra004382, (E) Bra019017 and (F) Bra028171.

Isolation of a papilla cell by LM in Arabidopsis and Brassica. The paraffin-embedded stigmas were cut into 6–8 µm thick sections using a microtome and mounted on PEN membrane frame slides. After removing the paraffin, LM was performed using an Arcturus XT Laser Capture Microdissection System. (A–C) Arabidopsis thaliana, (D–F) B. rapa, (A, D) before LM, (B, E) after LM, and (C, F) isolated papilla cells.

Classification of papilla-expressed genes by gene ontology, in A. thaliana, A. halleri and B. rapa. The pistil-expressed gene sets were sorted into six functional categories based on a functional classification of the genes, according to the gene ontology (GO) annotations (, ): signal transduction, cell wall-related, stress/defense, metabolism, ion transport and transcription.

Expression analysis of genes identified in the papilla by LM–RNA-seq. qRT-PCR was performed using the SYBR Green Real-Time PCR Master Mix with a Bio-Rad CFX96 Real-Time Detection System. cDNAs were prepared from total RNAs of stigma and leaf. Representation of the relative expression levels of the genes was normalized to the expression level of UBC21. Quantitative validation of three replicates was calculated using the delta–delta threshold cycle relative quantification method.