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The petals of ornamental plants such as roses (Rosa spp.) are the most economically important organs. This delicate, short-lived plant tissue is highly susceptible to pathogens, in large part because the walls of petal cells are typically thinner and more flexible compared with leaf cells, allowing the petals to fold and bend without breaking. The cell wall is a dynamic structure that rapidly alters its composition in response to pathogen infection, thereby reinforcing its stability and boosting plant resistance against diseases. However, little is known about how dynamic changes in the cell wall contribute to resistance to Botrytis cinerea in rose petals. Here, we show that the B. cinerea -induced transcription factor RhbZIP17 is required for the defense response of rose petals. RhbZIP17 is associated with phenylpropanoid biosynthesis and binds to the promoter of the lignin biosynthesis gene RhCAD1 , activating its expression. Lignin content showed a significant increase under gray mold infection compared with the control. RhCAD1 functions in the metabolic regulation of lignin production and, consequently, disease resistance, as revealed by transient silencing and overexpression in rose petals. The WRKY transcription factor RhWRKY30 is also required to activate RhCAD1 expression and enhance resistance against B. cinerea. We propose that RhbZIP17 and RhWRKY30 increase lignin biosynthesis, improve the resistance of rose petals to B. cinerea , and regulate RhCAD1 expression. [ABSTRACT FROM AUTHOR]

Background: Wall associated kinase (WAK) and WAK-like (WAKL) are typical pattern recognition receptors act as the first sentry of plant defense. But little of WAK/WAKL family is known in Rosaceae. Results: In this study, 131 WAK/WAKL genes from apple, peach and strawberry were identified using a bioinformatics approach. Together with 68 RcWAK/RcWAKL in rose, we performed a comparative analysis of 199 WAK/WAKL in four Rosaceae crops. The phylogenetic analysis divided all the WAK/WAKL into five clades. Among them, the cis-elements of Clade II and Clade V promoters were enriched in jasmonic acid (JA) signaling and abiotic stress, respectively. And this can also be verified by the rose transcriptome responding to different hormone treatments. WAK/WAKL families have experienced a considerable proportion of purifying selection during evolution, but still 26 amino acid sites evolved under positive selection, which focused on extracellular conserved domains. WAK/WAKL genes presented collinearity relationship within and between crops, throughout four crops we mined four orthologous groups (OGs). The WAK/WAKL genes in OG1 and OG4 were speculated to involve in plant-Botrytis cinerea interaction, which were validated in rose via VIGS as well as strawberry by qRT-PCR. Conclusions: These results not only provide genetic resources and valuable information for the evolutionary relationship of WAK/WAKL gene family, but also offer a reference for future in-depth studies of Rosaceae WAK/WAKL genes. [ABSTRACT FROM AUTHOR]

The TRICHOME BIREFRINGENCE-LIKE (TBL) family is an important gene family engaged in the O -acetylation of cell wall polysaccharides. There have been a few reports showing that TBL participated in the resistance against phytopathogens in Arabidopsis and rice. However, no relevant studies in rose (Rosa sp.) have been published. In this study, a genome-wide analysis of the TBL gene family in rose was presented, including their phylogenetic relationships, gene structure, chromosomal positioning, and collinearity analysis. The phylogenetic analysis revealed a total of 50 RcTBL genes in the rose genome, and they are unevenly distributed across all seven chromosomes. The occurrence of gene duplication events suggests that both the whole genome duplication and partial duplication may play a role in gene duplication of RcTBL s. The analysis of Ka/Ks showed that the replicated RcTBL genes underwent mainly purifying selection with limited functional differentiation. Gene expression analysis indicated that 12 RcTBL s were down-regulated upon the infection of Botrytis cinerea , the causal agent of the gray mold disease of rose. These RcTBL s may be a sort of candidate genes for regulating the response of rose to B. cinerea. Through virus-induced gene silencing, RcTBL16 was shown to be associated with susceptibility to gray mold in rose. Through this study, meaningful information for further studies on the function of the TBL protein family in rose is provided. [ABSTRACT FROM AUTHOR]

Fresh-cut roses (Rosa hybrida) are one of the most important ornamental crops worldwide, with annual trade in the billions of dollars. Gray mold disease caused by the pathogen Botrytis cinerea is the most serious fungal threat to cut roses, causing extensive postharvest losses. In this study, we optimized a detached petal disc assay (DPDA) for artificial B. cinerea inoculation and quantification of disease symptoms in rose petals. Furthermore, as the identification of rose genes involved in B. cinerea resistance could provide useful genetic and genomic resources, we devised a virus-induced gene silencing (VIGS) procedure for the functional analysis of B. cinerea resistance genes in rose petals. We used RhPR10.1 as a reporter of silencing efficiency and found that the rose cultivar 'Samantha' showed the greatest decrease in RhPR10.1 expression among the cultivars tested. To determine whether jasmonic acid and ethylene are required for B. cinerea resistance in rose petals, we used VIGS to silence the expression of RhLOX5 and RhEIN3 (encoding a jasmonic acid biosynthesis pathway protein and an ethylene regulatory protein, respectively) and found that petal susceptibility to B. cinerea was affected. Finally, a VIGS screen of B. cinerea-induced rose transcription factors demonstrated the potential benefits of this method for the high-throughput identification of gene function in B. cinerea resistance. Collectively, our data show that the combination of the DPDA and VIGS is a reliable and high-throughput method for studying B. cinerea resistance in rose. [ABSTRACT FROM AUTHOR]

• We have identified 48 RcbZIP family members in the whole genome of R. chinensis. • Their phylogenetic relationships, gene structure, chromosome localizations, and collinearity are investigated. • We further demonstrated that RcbZIP17 was involved in the regulation of B. cinerea resistance in rose petals. • These findings support the idea that RcbZIP family members play an important role in disease resistance. • This study provides useful information for studying the function of the bZIP genes in rose. Rose is an important ornamental plant and a commercial source of natural fragrances and essential oils. However, gray mold is the most serious disease of rose during cultivation and post-harvest. In plants, the bZIP gene family is one of the important families of transcription factors that regulate many biological processes, including pathogen defense, light response, and stress signaling. Although there were reports that bZIPs play a key role in plant pathogen defense, there have been no comprehensive studies or functional analysis of the bZIP gene family in rose (Rosa sp.) yet. In this study, a genome-wide analysis of the bZIP family gene (RcbZIPs) in rose was carried out to investigate their phylogenetic relationships, gene structure, chromosome localizations, collinearity, and the function of RcbZIP17. In the rose genome, 48 RcbZIP genes were identified and divided into 11 subgroups by phylogenetic relationships. Moreover, gene structure analysis agreed with phylogenetic tree grouping. The RcbZIPs were unevenly distributed on all seven chromosomes. The gene duplication events indicated that segmental duplication of the entire genome may play a key role in gene duplication. A Ka/Ks analysis showed that they mainly underwent purifying selection with limited functional differentiation. Gene expression analysis showed that 16 RcbZIPs were significantly differential expressed by Botrytis cinerea infection. It is speculated that these RcbZIPs are candidate genes for regulating the response of rose to gray mold infection. According to virus-induced gene silencing (VIGS) and overexpression (OE) studies, RcbZIP17 was implicated in the resistance of rose to gray mold. This study provides useful information for further study on the function of the bZIP gene family in rose. [ABSTRACT FROM AUTHOR]