Flower opening is an important process in the life cycle of flowering plants and is influenced by various endogenous and environmental factors. Our previous work demonstrated that rose (Rosa hybrida) flowers are highly sensitive to dehydration during flower opening and the water recovery process after dehydration induced ethylene production rapidly in flower gynoecia. In addition, this temporal- and spatial-specific ethylene production is attributed to a transient but robust activation of the rose MAP KINASE6-ACC SYNTHASE1 (RhMPK6-RhACS1) cascade in gynoecia. However, the upstream component of RhMPK6-RhACS1 is unknown, although RhMKK9 (MAP KINASE KINASE9), a rose homologue of Arabidopsis MKK9, could activate RhMPK6 in vitro. In this study, we monitored RhMKK2/4/5/9 expression, the potential upstream kinase to RhMPK6, in rose gynoecia during dehydration and rehydration. We found only RhMKK9 was rapidly and strongly induced by rehydration. Silencing of RhMKK9 significantly decreased rehydration-triggered ethylene production. Consistently, the expression of several ethylene-responsive genes was down regulated in the petals of RhMKK9-silenced flowers. Moreover, we detected the DNA methylation level in the promoter and gene body of RhMKK9 by Chop-PCR. The results showed that rehydration specifically elevated the DNA methylation level on the RhMKK9 gene body, whereas it resulted in hypomethylation in its promoter. Our results showed that RhMKK9 possibly acts as the upstream component of the RhMKK9-RhMPK6-RhACS1 cascade and is responsible for water recovery-triggered ethylene production in rose gynoecia, and epigenetic DNA methylation is involved in the regulation of RhMKK9 expression by rehydration.

Gray mold of roses, caused by the necrotrophic fungal pathogen Botrytis cinerea, is an economically notorious disease and a well-known economic menace, leading to substantial annual losses estimated at no less than 30% of production. This disease takes a toll not only on the marketability of cut rose flowers but also on consumer and importer confidence due to the unsightly symptoms it induces. This fungus influences the rose foliage throughout cultivation, transportation, storage, and marketing. The interplay of conducive environmental conditions and genetic factors plays significant roles in developing the rose gray mold on rose flowers during the pre- and post-harvest phases. Nevertheless, the molecular mechanisms underlying B. cinerea-rose interactions are poorly understood, and the knowledge of how rose plants defend themselves against B. cinerea infection is not comprehensively investigated. It is worth noting that breeding for resistance to discover genetically resistant roses toward gray mold was unsuccessful despite research conducted over the past century. Consequently, synthetic fungicides remain the primary approach to controlling Botrytis blight in roses during the pre- and post-harvest stages. However, this measure has several drawbacks, including the emergence of fungicide-resistant B. cinerea and endangering human and animal health due to chemical residues in the food chain. This review aims to offer a comprehensive update on recent research findings on the biology and management of B. cinerea infection in roses and to propose novel strategies for managing gray mold disease.

In this study, the mitochondrial genomes of two calla species, Zantedeschia aethiopica Spreng. and Zantedeschia odorata Perry., were assembled and compared for the first time. The Z. aethiopica mt genome was assembled into a single circular chromosome, measuring 675,575 bp in length with a 45.85% GC content. In contrast, the Z. odorata mt genome consisted of bicyclic chromosomes (chromosomes 1 and 2), measuring 719,764 bp and exhibiting a 45.79% GC content. Both mitogenomes harbored similar gene compositions, with 56 and 58 genes identified in Z. aethiopica and Z. odorata, respectively. Analyses of codon usage, sequence repeats, gene migration from chloroplast to mitochondrial, and RNA editing were conducted for both Z. aethiopica and Z. odorata mt genomes. Phylogenetic examination based on the mt genomes of these two species and 30 other taxa provided insights into their evolutionary relationships. Additionally, the core genes in the gynoecium, stamens, and mature pollen grains of the Z. aethiopica mt genome were investigated, which revealed maternal mitochondrial inheritance in this species. In summary, this study offers valuable genomic resources for future research on mitogenome evolution and the molecular breeding of calla lily.

Rose (Rosa chinensis Jacq.) is an important economic ornamental crop and its yield is affected by different biotic and abiotic stresses. Among the biotic stresses, the gray mold disease caused by Botrytis cinerea is a serious threat to rose production. The basic helix-loop-helix (bHLH) is a large transcription factor family involved in several vital plant physiological processes, including growth, development, and stress response. However, no substantial reports exist on bHLH genes in rose. Here, the genome-wide identification, characterization, and expression analysis of the rose bHLH (RcbHLH) genes was carried out. In total, 100 RcbHLHs were identified in the rose genome and mapped onto different rose chromosomes. The gene duplication analysis revealed both tandem and segmental duplications in RcbHLHs. The RcbHLHs among other plant bHLHs were divided into 21 sub-groups on the phylogenetic tree. Additionally, prediction of the different cis-regulatory elements and the gene ontology of the identified RcbHLHs indicated their possible functions in rose plants. The expression analysis of selected RcbHLHs genes in two contrasting rose varieties (A29 = Black Baccara and XS = Sweet Avalanche) under B. cinerea infection provided insights into the involvement of RcbHLHs in rose–B. cinerea interactions. Moreover, this study provided details on the bHLH family genes in rose and their potential roles in rose defense against B. cinerea infection.

Background: The plant cysteine-rich receptor-like kinases (CRKs) are a large family having multiple roles, including defense responses under both biotic and abiotic stress. However, the CRK family in cucumbers (Cucumis sativus L.) has been explored to a limited extent. In this study, a genome-wide characterization of the CRK family has been performed to investigate the structural and functional attributes of the cucumber CRKs under cold and fungal pathogen stress. Results: A total of 15 C. sativus CRKs (CsCRKs) have been characterized in the cucumber genome. Chromosome mapping of the CsCRKs revealed that 15 genes are distributed in cucumber chromosomes. Additionally, the gene duplication analysis of the CsCRKs yielded information on their divergence and expansion in cucumbers. Phylogenetic analysis divided the CsCRKs into two clades along with other plant CRKs. Functional predictions of the CsCRKs suggested their role in signaling and defense response in cucumbers. The expression analysis of the CsCRKs by using transcriptome data and via qRT-PCR indicated their involvement in both biotic and abiotic stress responses. Under the cucumber neck rot pathogen, Sclerotium rolfsii infection, multiple CsCRKs exhibited induced expressions at early, late, and both stages. Finally, the protein interaction network prediction results identified some key possible interacting partners of the CsCRKs in regulating cucumber physiological processes. Conclusions: The results of this study identified and characterized the CRK gene family in cucumbers. Functional predictions and validation via expression analysis confirmed the involvement of the CsCRKs in cucumber defense response, especially against S. rolfsii. Moreover, current findings provide better insights into the cucumber CRKs and their involvement in defense responses.

Background: Solanum muricatum is an emerging horticultural fruit crop with rich nutritional and antioxidant properties. Although the chromosome-scale genome of this species has been sequenced, its mitochondrial genome sequence has not been reported to date. Results: PacBio HiFi sequencing was used to assemble the circular mitogenome of S. muricatum, which was 433,466 bp in length. In total, 38 protein-coding, 19 tRNA, and 3 rRNA genes were annotated. The reticulate mitochondrial conformations with multiple junctions were verified by polymerase chain reaction, and codon usage, sequence repeats, and gene migration from chloroplast to mitochondrial genome were determined. A collinearity analysis of eight Solanum mitogenomes revealed high structural variability. Overall, 585 RNA editing sites in protein coding genes were identified based on RNA-seq data. Among them, mttB was the most frequently edited (52 times), followed by ccmB (46 times). A phylogenetic analysis based on the S. muricatum mitogenome and those of 39 other taxa (including 25 Solanaceae species) revealed the evolutionary and taxonomic status of S. muricatum. Conclusions: We provide the first report of the assembled and annotated S. muricatum mitogenome. This information will help to lay the groundwork for future research on the evolutionary biology of Solanaceae species. Furthermore, the results will assist the development of molecular breeding strategies for S. muricatum based on the most beneficial agronomic traits of this species.