Integrated transcriptome and endogenous hormone analysis provides new insights into callus proliferation in Osmanthus fragrans

Abstract

Osmanthus fragrans is an important evergreen species with both medicinal and ornamental value in China. Given the low efficiency of callus proliferation and the difficulty of adventitious bud differentiation, tissue culture and regeneration systems have not been successfully established for this species. To understand the mechanism of callus proliferation, transcriptome sequencing and endogenous hormone content determination were performed from the initial growth stages to the early stages of senescence on O. fragrans calli. In total, 47,340 genes were identified by transcriptome sequencing, including 1798 previously unidentified genes specifically involved in callus development. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of differentially expressed genes (DEGs) was significantly enriched in plant hormone signal transduction pathways. Furthermore, our results from the orthogonal projections to latent structures discrimination analysis (OPLS-DA) of six typical hormones in five development stages of O. fragrans calli showed jasmonic acid (JA) could play important role in the initial stages of calli growth, whereas JA and auxin (IAA) were dominant in the early stages of calli senescence. Based on the weighted gene co-expression network analysis, OfSRC2, OfPP2CD5 and OfARR1, OfPYL3, OfEIL3b were selected as hub genes from the modules with the significant relevance to JA and IAA respectively. The gene regulation network and quantitative real-time PCR implied that during the initial stages of callus growth, the transcription factors (TFs) OfERF4 and OfMYC2a could down-regulate the expression of hub genes OfSRC2 and OfPP2CD5, resulting in decreased JA content and rapid callus growth; during the late stage of callus growth, the TFs OfERF4, OfMYC2a and OfTGA21c, OfHSFA1 could positively regulate the expression of hub genes OfSRC2, OfPP2CD5 and OfARR1, OfPYL3, OfEIL3b, respectively, leading to increased JA and IAA contents and inducing the senescence of O. fragrans calli. Hopefully, our results could provide new insights into the molecular mechanism of the proliferation of O. fragrans calli.

Integrated transcriptomic and endogenous hormones analyses revealed the molecular mechanism of light and auxin for the regeneration of callus tissue in seashore paspalum

“…The process of callus regeneration is closely related to the types, concentrations, and dynamic balance of endogenous hormones in callus that were also controlled by exogenous hormones [23]. The beginning of proliferation centers in explants and the plant architecture are impacted by the amounts of endogenous hormones [36].…”

“…Transcriptome studies make it possible to e ciently and quickly analyze differentially expressed genes and functionally annotate regulatory pathways [22]. Integrated transcriptomic and endogenous hormone content analysis insighted uncovering regeneration mechanism in Osmanthus fragrans calli [23]. Some potential genes linked to somatic embryogenesis were discovered by examining the transcriptome pro le and gene expression regulation alterations of embryogenic callus and redifferentiation in hybrid sweetgum [24].…”

Recent Advances in Flower Color and Fragrance of Osmanthus fragrans

“…This line of research requires the identification of genes encoding enzymes involved in the synthesis of flower color and fragrance substances and the determination of how the expression of these genes is regulated, which may require the use of transgenic model plants [83]. Meanwhile, existing research shows that calli and others have carried out tissue culture of O. fragrans [84,85], but due to the low efficiency of callus tissue proliferation and the difficulty of differentiation of indefinite buds, the tissue culture and regeneration system of O. fragrans has not been successfully established [86]. The lack of complete sequencing of the O. fragrans genome may limit the cloning of O. fragrans genes and the development of gene transformation requires a stable O. fragrans tissue culture technology.…”

DNA-Binding One Finger Transcription Factor PhDof28 Regulates Petal Size in Petunia

“…To quantify hormone content, wild-type and F 1 transgenic petunia petals at the semiand full-flowering stages were separately gathered in four biological replicates. Samples were ground in liquid nitrogen, then extracted with an extraction buffer prior to measurement of hormone content in petals with the ELISA method [34,35].…”