Transcriptome And Proteome Analysis Of Pollen-Silk Interactions In Maize

Pollen-silk interactions plays vital role in higher plant reproduction. In maize (Zea mays L.), the silks provide initial nutrients and guidance for pollen grain germination and pollen tube growth. The high degree of specificity in pollen-silk interactions and the precision of directional pollen tube growth suggest that signals are continually being exchanged between pollen tubes and cells of the pistil that line their path. However, little is known about the genes that regulate these processes in maize. Here, we studied the pollen-pistil interaction in maize through transcriptome and proteome analysis. In the current study, through the dynamic monitoring of the process of pollen-silk interactions in maize inbred line B73, two critical time points were determined:1h and 5h after pollination (HAP) represented the stages of pollen germination and pollen tube growth in the style, respectively. Total RNA and proteins of silks of B73 at 1 and 5 HAP were extracted and used for transcriptome and proteome analysis.1.Compared with the unpollinated mature silks, there were a total of 1852 differentially-expressed genes (DEGs) and 185 specifically-expressed genes in the silks at 1 HAP. While, compared with the silks at 1 HAP, there were only 330 DEGs in the silks at 5 HAP. Function analysis showed that most of the well-annotated genes were involved in DNA binding, biological regulation, transcription factor activity, response to stimulus and RNA biosynthetic process. Moreover, the DEGs concentrated in the cytoplasm and the organelles, had catalytically active transferase activity and lipid binding activity, involved in photosynthesis, cell metabolism of amino acids and secondary decomposition process.2.Pathway analysis showed that biochemical pathways were mainly involved in photosynthesis, antenna protein metabolic, arginine and proline metabolism, amino sugar and nucleotide metabolism, splicing complexes and other channels.3.A total of 67 differentially-expressed proteins were detected among the silks of 3 stages and 36 were identified by MALDI-TOF-MS and MASCOT analysis. Functional analysis showed that the proteins involved in pectin methylesterase inhibitor, glutathione S-transferase, leucine-rich repeats domain, and ABC transporter may play important roles in maize pollen-pistil interactions.4.Transcriptome and proteome homology analysis showed that there were 12 identified proteins having the same expression pattern with the DEGs of transcriptome. The expression level of the remaining differentially expressed proteins were relatively high in transcriptome expression profile but there was no significant difference. It indicated that the transcript expression level might be not a good predictor for protein abundance or its variation among different stages. For example, Glutathione S-transferases (GSTs), Leucine-rich repeats (LRRs), Pectin methylesterase inhibitor may play important roles in pollen-pistil interaction.