RcNAC72, a key transcription factor that may respond to drought stress in Rosa chinensis ‘Old Blush’, was selected in our previous study. In the present study, we found that RcNAC72 is localized in the nucleus and is a transcriptional activator. RcNAC72 expression could be significantly induced by drought, low temperature, salt as well as abscisic acid (ABA) treatment. Analysis of the promoter revealed that multiple abiotic stress and hormone response elements were located in the promoter region. The promoter could respond to drought, low temperature, salt and ABA treatments to activate GUS gene expression. Overexpressing RcNAC72 in Arabidopsis thaliana enhanced sensitivity to ABA and tolerance to drought stress. Silencing of RcNAC72 by virus-induced gene silencing (VIGS) in rose leaves significantly reduced leaf water loss tolerance and leaf extension capacity. Physical interaction of RcNAC72 with RcDREB2A was shown by means of the yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. RcABF4 was demonstrated to be able to bind to the promoter of RcNAC72 by means of the yeast one-hybrid (Y1H) assay. These results provide new insights into the regulatory network of RcNAC72 response to drought stress in roses.

Rose is one of the most fundamental ornamental crops, but its yield and quality are highly limited by drought. The key transcription factors (TFs) and co-expression networks during rose’s response to drought stress and recovery after drought stress are still limited. In this study, the transcriptomes of leaves of 2-year-old cutting seedlings of Rosa chinensis ‘Old Blush’ from three continuous droughted stages (30, 60, 90 days after full watering) and rewatering were analyzed using RNA sequencing. Weighted gene co-expression network analysis (WGCNA) was used to construct a co-expression network, which was associated with the physiological traits of drought response to discovering the hub TFs involved in drought response. More than 45 million high-quality clean reads were generated from the sample and used for comparison with the rose reference genome. A total of 46433 differentially expressed genes (DEGs) were identified. Gene Ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that drought stress caused significant changes in signal transduction, plant hormones including ABA, auxin, brassinosteroid (BR), cytokinin, ethylene (ET), jasmonic acid (JA) and salicylic acid (SA), primary and secondary metabolism, and a certain degree of recovery after rewatering. Gene co-expression analysis identified 18 modules, in which four modules showed a high degree of correlation with physiological traits. In addition, 42 TFs including members of NACs, WRKYs, MYBs, AP2/ERFs, ARFs, and bHLHs with high connectivity in navajowhite1 and blue modules were screened. This study provides the transcriptome sequencing report of R. chinensis ‘Old Blush’ during drought stress and rewatering process. The study also identifies the response of candidate TFs to drought stress, providing guidelines for improving the drought tolerance of the rose through molecular breeding in the future.

Light plays a crucial role in regulating anthocyanin biosynthesis during flower coloration. However, the involvement of epigenetic modifications in light-induced flower coloration remains poorly understood. Here, we studied the rose cultivar Rosa hybrida cv. Spectra, which exhibits dramatic light-induced changes in petal coloration. Integrated analysis of the m⁶A methylome and the transcriptome revealed significant changes in both m⁶A modifications and the expression of the anthocyanidin synthase gene RhANS (C_AA159414.1) in response to direct light in the petals. Light induced m⁶A modifications in the coding sequence (CDS) region of RhANS and repressed m⁶A modification at the 3′ untranslated region (3′UTR). m⁶A modification in the CDS region enhanced mRNA stability and the translation efficiency of RhANS, whereas modification in the 3′UTR exerted an opposing effect. The expression of the m⁶A demethylase genes RhALKBH10A (C_AA159415.1) and RhALKBH10B (C_AA159416.1) was repressed in petals under direct light conditions. Silencing RhALKBH10A/10B enhanced anthocyanin accumulation, increased m⁶A abundance at CDS sites, and concurrently reduced m⁶A abundance at the 3′UTR site of RhANS mRNA. Silencing RhANS abrogated the anthocyanin accumulation induced by RhALKBH10A/10B silencing. Our results reveal that light modulates m⁶A modifications to regulate mRNA stability and translation of RhANS, thereby driving petal coloration in rose.

Background: Rose is one of the most important ornamental crops, but drought limits its yield and quality seriously. Although serval abiotic stress related genes have been identified, the molecular mechanism during rose’s responding to drought stress is still limited. In this study, the transcriptomes of leaves of two-year-old cutting seedlings of Rosa chinensis ’Old Blush’ from three continuous droughted stages (30, 60, 90 days after full watering) and rewatering were analyzed using RNA sequencing. Meanwhile, weighted gene co-expression network analysis (WGCNA) was used to construct a co-expression network associated with the physiological traits of drought response to discover the hub transcription factors involved in drought response.Results: More than 45 million high-quality clean reads were generated from samples and used for comparison with the rose reference genome. A total of 46433 differentially expressed genes were identified. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that drought stress caused significant changes in signal transduction, plant hormones, primary and secondary metabolism, and a certain degree of recovery after rewatering. Gene co-expression analysis identified 18 modules, in which four modules have highly degree of correlation with physiological traits. In addition, twenty-two transcription factors including members of NACs, WRKYs, MYBs, ERFs, ARFs and bHLHs with high connectivity in these four modules were screened. Conclusions: The results of this study provided the first transcriptome sequencing report of the drought stress in R.chinensis, and also provided candidate transcription factors in response to drought stress, providing clues for improving the drought tolerance of the rose through molecular breeding in the future.