Transcriptomic Analysis for Different Sex Types of Ricinus communis L. during Development from Apical Buds to Inflorescences by Digital Gene Expression Profiling

Abstract

The castor plant (Ricinus communis L.) is a versatile industrial oilseed crop with a diversity of sex patterns, its hybrid breeding for improving yield and high purity is still hampered by genetic instability of female and poor knowledge of sex expression mechanisms. To obtain some hints involved in sex expression and provide the basis for further insight into the molecular mechanisms of castor plant sex determination, we performed DGE analysis to investigate differences between the transcriptomes of apices and racemes derived from female (JXBM0705P) and monoecious (JXBM0705M) lines. A total of 18 DGE libraries were constructed from the apices and racemes of a wild monoecious line and its isogenic female derivative at three stages of apex development, in triplicate. Approximately 5.7 million clean tags per library were generated and mapped to the reference castor genome. Transcriptomic analysis showed that identical dynamic changes of gene expression were indicated in monoecious and female apical bud during its development from vegetation to reproduction, with more genes expressed at the raceme formation and infant raceme stages compare to the early leaf bud stage. More than 3000 of differentially expressed genes (DEGs) were detected in Ricinus apices at three developmental stages between two different sex types. A number of DEGs involved in hormone response and biosynthesis, such as auxin response and transport, transcription factors, signal transduction, histone demethylation/methylation, programmed cell death, and pollination, putatively associated with sex expression and reproduction were discovered, and the selected DEGs showed consistent expression between qRT-PCR validation and the DGE patterns. Most of those DEGs were suppressed at the early leaf stage in buds of the mutant, but then activated at the following transition stage (5-7-leaf stage) of buds in the mutant, and ultimately, the number of up-regulated DEGs was equal to that of down-regulation in the small raceme of the mutant. In this study, a large number of DEGs and some suggestions involved in sex expression and reproduction were discovered using DGE analysis, which provides large information and valuable hints for next insights into the molecular mechanism of sex determination. It is useful for other further studies in Ricinus.

Comparative transcriptome analysis reveals the regulatory networks of cytokinin in promoting the floral feminization in the oil plant Sapium sebiferum

“…It has been demonstrated that auxin was important for the female reproductive organ development in Arabidopsis [ 51 ], and also exhibited a strong feminization effect on Cannabis sativus and Opuntia stenopetala [ 5 , 31 ]. The expression of auxin signaling genes was also positively correlated with the transition to female flowers on the monoecious Ricinus communis [ 52 ]. Our results were in accord with these findings that auxin could also play important role in the female flower induction regulated by cytokinin in S. sebiferum .…”

Comparative de novo flower transcriptome analysis of polygamodioecious tree Garcinia indica

“…In BS vs ML and FL vs ML libraries, the genes were distinctly up-regulated, but downregulated in BS vs FL. Similarly, genes like DNA replication helicase (dna2) and sam50 which are known to be associated with the developmental process in reproduction were found up-regulated in BS vs ML and FL vs ML (Table S8) (Tan et al 2016).…”

“…Auxin response factor is known to respond hormone stimulus which participates in hormone-mediated signaling pathways, and also plays a role in tissue and organ developmental processes (Tan et al 2016). In addition, 12 gene (arginine/serine-rich splicing factor) associated with sex differentiation were identified.…”

“…The mRNA transcripts' sequencing generates high functional information content that can be used to identify new and novel genes with the known or predicted functions (Andersen and Lubberstedt 2003;Bouck and Vision 2007). Many studies have been conducted in candidate genes for sex determination such as Ricinus communis (Tan et al 2016), Carica papaya (Zeng et al 2014), and Eucalyptus grandis (Vining et al 2015) and others.…”

A comparative transcriptional landscape of two castor cultivars obtained by single-molecule sequencing comparative analysis

“…High ricinoleic acid content (80-90%) and high fatty acid content (more than 45%) in seed oil make oit one of the most important non-edible oilseed crops, and has attracted much attention of chemists, biologists and medical scientists [1]. The inflorescence of common castor plants is gradient monoecious raceme, with staminate flowers on the lower portion and female flowers at the apex[2]. Pistillate (bearing only female flowers) variations are bred to improve the seed yield.…”