Transcriptome analysis reveals the regulation of brassinosteroids on petal growth in Gerbera hybrida

Abstract

Gerbera hybrida is a cut-flower crop of global importance, and an understanding of the mechanisms underlying petal development is vital for the continued commercial development of this plant species. Brassinosteroids (BRs), a class of phytohormones, are known to play a major role in cell expansion, but their effect on petal growth in G. hybrida is largely unexplored. In this study, we found that the brassinolide (BL), the most active BR, promotes petal growth by lengthening cells in the middle and basal regions of petals, and that this effect on petal growth was greater than that of gibberellin (GA). The RNA-seq (high-throughput cDNA sequencing) technique was employed to investigate the regulatory mechanisms by which BRs control petal growth. A global transcriptome analysis of the response to BRs in petals was conducted and target genes regulated by BR were identified. These differentially expressed genes (DEGs) include various transcription factors (TFs) that were activated during the early stage (0.5 h) of BL treatment, as well as cell wall proteins whose expression was regulated at a late stage (10 h). BR-responsive DEGs are involved in multiple plant hormone signal pathways, hormone biosynthesis and biotic and abiotic stress responses, showing that the regulation of petal growth by BRs is a complex network of processes. Thus, our study provides new insights at the transcriptional level into the molecular mechanisms of BR regulation of petal growth in G. hybrida.

GhWIP2, a WIP zinc finger protein, suppresses cell expansion in Gerbera hybrida by mediating crosstalk between gibberellin, abscisic acid, and auxin

“…Accumulating evidence suggests that phytohormones play vital roles in this process. GAs, auxin and brassinosteroids (BRs) have been shown to promote cell expansion (Heo et al ., ; Band et al ., ; Li et al ., ; Velasquez et al ., ; Huang et al ., ), whereas ABA, ethylene (ET) and jasmonic acid (JA) represses this process (Szécsi et al ., ; Pei et al ., ; Li et al ., ). In addition, crosstalk between different phytohormones in regulating cell expansion has also been demonstrated, and transcription factors (TFs) play key roles in integrating different phytohormone signals.…”

Transcriptomic analysis of flower opening response to relatively low temperatures in Osmanthus fragrans

“…However, seven of fteen unigenes in this signal pathway were decreased under 19°C treatment. In G. hybrida, the expression level of BES1/BZR1 was decreased after only 0.5 h BR treatment, indicating its vital role in petal cell expansion [21]. The expression level of BZR1/2 was eight-fold under 19°C compared to 23°C, and the expression level were continuously increased as the treatment time prolonged, suggesting the same role of BZR1/2 in petal development of O. fragrans and G. hybrida.…”

“…Phytohormones are the most important mediators regulating ower opening and could be affected by circadian factors or environmental factors. As far as the present researches are concerned, most of the phytohormones, such as auxin (AUX), gibberellin (GA), ethylene (ETH), brassinosteroid (BR), jasmonic acid (JA) and abscisic acid (ABA), are proven to affect ower opening [5,6,[20][21][22].…”

An ETHYLENE INSENSITIVE3-LIKE1 Protein Directly Targets the GEG Promoter and Mediates Ethylene-Induced Ray Petal Elongation in Gerbera hybrida

“…Another class of plant hormones, brassinosteroids (BRs), promotes petal growth by regulating cell expansion in gerbera. Transcriptome analysis showed that various TFs are activated by brassinolide 0.5 h after treatment, whereas cell wall protein genes are regulated at 10 h (Huang et al, 2017).…”