RNA-Seq Analysis of Wild Type and pSTK::amiRNACWIN24 (4-3) Transcriptomes

ABSTRACT: Ovule formation is essential for realizing crop yield as it determines seed number. The underlying molecular mechanism, however, remains elusive. Here, we show that cell wall invertase (CWIN) functions as a positive regulator of ovule initiation in Arabidopsis. In situ hybridization revealed that CWIN2 and CWIN4 were expressed at the placenta region where ovule primordia initiated. Specific silencing of CWIN2 and 4 by using targeted artificial microRNA driven by an ovule-specific SEEDSTICK promoter (pSTK) resulted in a significant reduction of CWIN transcript and activity, which blocked ovule initiation and aggravated ovule abortion. Surprisingly, there was no induction of carbon starvation genes in the transgenic lines and supplement of extra carbon to newly forming floral buds failed to recover the ovule phenotype. The findings indicate that suppression of CWIN did not lead to carbon starvation. Interestingly, a group of hexose transporters was downregulated in the transgenic plants and two representative transporter genes, STP9 and SWEET8 were spatially co-expressed with CWIN2 and CWIN4, suggesting a coupling between CWIN and hexose transporters for ovule initiation. RNA-Seq analysis identified differentially expressed genes encoding putative extracellular receptor-like-kinases (RLKs), MADS-box transcription factors including STK and early auxin response genes, SAURs, in response to CWIN-silencing. Collectively, our data demonstrate the essential role that CWIN plays in ovule initiation likely through sugar signalling instead of carbon nutrient contribution. We propose that CWIN-mediated sugar signalling may be perceived by, and transmitted through, hexose transporters or RLKs to regulate ovule formation by modulating downstream auxin signalling and MADS-box transcription factors.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE139917 | GEO | 2020/02/29

REPOSITORIES: GEO