Transcriptome landscape of Rafflesia cantleyi floral buds reveals insights into the roles of transcription factors and phytohormones in flower development

Abstract

Rafflesia possesses unique biological features and known primarily for producing the world’s largest and existing as a single flower. However, to date, little is known about key regulators participating in Rafflesia flower development. In order to further understand the molecular mechanism that regulates Rafflesia cantleyi flower development, RNA-seq data from three developmental stages of floral bud, representing the floral organ primordia initiation, floral organ differentiation, and floral bud outgrowth, were analysed. A total of 89,890 transcripts were assembled of which up to 35% could be annotated based on homology search. Advanced transcriptome analysis using K-mean clustering on the differentially expressed genes (DEGs) was able to identify 12 expression clusters that reflect major trends and key transitional states, which correlate to specific developmental stages. Through this, comparative gene expression analysis of different floral bud stages identified various transcription factors related to flower development. The members of WRKY, NAC, bHLH, and MYB families are the most represented among the DEGs, suggesting their important function in flower development. Furthermore, pathway enrichment analysis also revealed DEGs that are involved in various phytohormone signal transduction events such as auxin and auxin transport, cytokinin and gibberellin biosynthesis. Results of this study imply that transcription factors and phytohormone signalling pathways play major role in Rafflesia floral bud development. This study provides an invaluable resource for molecular studies of the flower development process in Rafflesia and other plant species.

Functional Characterization of the EMBRYONIC FLOWER 2 Gene Involved in Flowering in Ginkgo biloba

“…The TFs, including MYB , bHLH , NAC , and WRKY , play essential roles in the reproductive development of plants. The MYB genes are potentially involved in flower development in Rafflesia cantleyi ( Amini et al, 2019 ). Some genes of bHLH families act as flower developmental regulators that control flowering time ( Ito et al, 2012 ).…”

“…Given the joint analysis of our data and flowering-related genes, we speculated that GbEMF2 may control the flowering process by regulating the expression of SUS3, BAM1, and AMY1 (Figure 9). (Amini et al, 2019). Some genes of bHLH families act as flower developmental regulators that control flowering time (Ito et al, 2012).…”

A PRELIMINARY STUDY OF IN VIVO INJECTION OF AUXIN AND CYTOKININ INTO Rafflesia patma Blume FLOWER BUDS

“…Hence, it is possible that some primordial tissue in Rafflesia plays a role in auxin production. In Rafflesia, auxin and cytokinin actively play a role during flower development, with cytokinin mainly regulating flower development by activating MADS-box transcriptional factor genes (Amini et al 2019).…”

“…flower bud and ovule formation, and regulates flower and seed size (van der Krieken 1989; Bartrina et al 2011). The effect of these regulators on the growth of Rafflesia cantleyi Solms-Laubach was observed in a transcriptomic study of genes and transcription factors related to auxin, cytokinin, gibberellin, abscisic acid, and jasmonic acid (Amini et al 2019). As Rafflesia endophyte growth is cryptic, observations on the effects of PGR on flower growth can only be done via two possible ways, i.e.…”

Cross-Talk between Transcriptome Analysis and Dynamic Changes of Carbohydrates Identifies Stage-Specific Genes during the Flower Bud Differentiation Process of Chinese Cherry (Prunus pseudocerasus L.)

“…Changes in nutrient signaling stimulate phytohormone signaling, and the synergistic action of the two nutrients may regulate plant growth and development. Several clearly defined types of plant hormones have been recognized, including gibberellin (GA), auxin, cytokinin (CK), and abscisic acid (ABA) [ 12 ], which may regulate the expression of corresponding genes responding to flower bud differentiation [ 13 ].…”