Transcriptomic analysis reveals ethylene signal transduction genes involved in pistil development of pumpkin.

Qingfei Li,Helian Yang,Feifei Pan,Bihua Chen,Guangyin Wang,Li Zhang,Weili Guo,Xinzheng Li

doi:10.7717/peerj.9677

Abstract

Development of female flowers is an important process that directly affects the yield of Cucubits. Little information is available on the sex determination and development of female flowers in pumpkin, a typical monoecious plant. In the present study, we used aborted and normal pistils of pumpkin for RNA-Seq analysis and determined the differentially expressed genes (DEGs) to gain insights into the molecular mechanism underlying pistil development in pumpkin. A total of 3,817 DEGs were identified, among which 1,341 were upregulated and 2,476 were downregulated. The results of transcriptome analysis were confirmed by real-time quantitative RT-PCR. KEGG enrichment analysis showed that the DEGs were significantly enriched in plant hormone signal transduction and phenylpropanoid biosynthesis pathway. Eighty-four DEGs were enriched in the plant hormone signal transduction pathway, which accounted for 12.54% of the significant DEGs, and most of them were annotated as predicted ethylene responsive or insensitive transcription factor genes. Furthermore, the expression levels of four ethylene signal transduction genes in different flower structures (female calyx, pistil, male calyx, stamen, leaf, and ovary) were investigated. The ethyleneresponsive DNA binding factor, ERDBF3, and ethylene responsive transcription factor, ERTF10, showed the highest expression in pistils and the lowest expression in stamens, and their expression levels were 78- and 162-times more than that in stamens, respectively. These results suggest that plant hormone signal transduction genes, especially ethylene signal transduction genes, play an important role in the development of pistils in pumpkin. Our study provides a theoretical basis for further understanding of the mechanism of regulation of ethylene signal transduction genes in pistil development and sex determination in pumpkin.

Highlights

Pumpkin (Cucurbita moschata Duch.) is a typical monoecious plant with distinct male and female flowers
The results of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the differentially expressed genes (DEGs) were enriched in plant hormone signal transduction pathway, and most of them were annotated as predicated ethylene-responsive transcription factor, ethylene insensitive transcription factor, and ethylene receptor genes (Table S5)
These results indicate that ethylene signal transduction genes, ERTF10 and ERDBF3, may be more important in the pistils of female flowers than in other floral structures

Summary

Introduction

Pumpkin (Cucurbita moschata Duch.) is a typical monoecious plant with distinct male and female flowers. The number and proportion of female flowers can directly influence yields and economic benefits of Cucurbitaceae crops. Transcriptomic analysis reveals ethylene signal transduction genes involved in pistil development of pumpkin. It is well established that ethylene promotes pistil and female flower development. Ethylene promotes carpel development and arrests stamen development in female flower (Chen et al, 2016). Treatment with exogenous ethylene or ethylene releasing reagents can increase the numbers of female and bisexual flowers in monoecious and andromonoecious lines, respectively (Iwahori, Lyons & Sims, 1969; Malepszy & Niemirowicz-Szczytt, 1991; Manzano et al, 2011). The development of female flowers is inseparable from sex differentiation in Cucurbitaceae crops

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Discussion

Conclusion