Petal senescence involves numerous programmed changes in biological and biochemical processes. Ubiquitination plays a critical role in protein degradation, a hallmark of organ senescence. Therefore, we investigated changes in the proteome and ubiquitome of senescing rose (Rosa hybrida) petals to better understand their involvement in petal senescence. Of 3859 proteins quantified in senescing petals, 1198 were upregulated, and 726 were downregulated during senescence. We identified 2208 ubiquitinated sites, including 384 with increased ubiquitination in 298 proteins and 1035 with decreased ubiquitination in 674 proteins. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that proteins related to peptidases in proteolysis and autophagy pathways were enriched in the proteome, suggesting that protein degradation and autophagy play important roles in petal senescence. In addition, many transporter proteins accumulated in senescing petals, and several transport processes were enriched in the ubiquitome, indicating that transport of substances is associated with petal senescence and regulated by ubiquitination. Moreover, several components of the brassinosteroid (BR) biosynthesis and signaling pathways were significantly altered at the protein and ubiquitination levels, implying that BR plays an important role in petal senescence. Our data provide a comprehensive view of rose petal senescence at the posttranslational level.

Molecular vegetable breeding has been progressed intensively in recent years. Huge advances have been made in germplasm evaluation, gene isolation, plant transformation, gene editing and molecular-marker-assisted breeding. The goal of this Special Issue is to highlight, through selected works, frontier research from basic to applied molecular vegetable breeding. The selected papers published in Special Issue of Horticulturae exhibit a diversity in molecular vegetable breeding. The papers listed in this editorial are especially noteworthy.

BRs (Brassinosteroids) regulate many essential pathways related to growth, cell elongation, cell expansion, plant architecture, and fruit development. The potential exogenous application of BR-derivatives has been proven to stimulate plant growth and development, including quality attributes of fruits, whereas its biosynthesis inhibition has shown the opposite effect. In this study, BR-insensitive tomato mutants were used to reveal the potential function of BR signaling in the regulation of fruit development to elaborate the regulatory mechanism of BR signaling in tomato fruits. The BR-signaling mutant exhibited a typical dwarf phenotype and reduced vegetative growth, fruit size, and weight. Microscopic and transcriptional evaluation of the abs1 mutant fruits implies that reduced cell size and number are responsible for the phenotypic variations. Additionally, we also found that the altered content of phytohormones, such as auxin, gibberellin, cytokinin, and ethylene levels, contributed to altered fruit development. Moreover, fruit growth and cell development-specific gene expression levels were downregulated in BR-insensitive plants; culminating in reduced cell size, cell number, and cell layers. These findings provide insight into physio-chemical changes during fruit development in response to BR-insensitivity.

Anthurium andraeanum Linden is a prominent ornamental plant belonging to the family Araceae and is cultivated worldwide. The morphology characteristics are crucial because they significantly impact ornamental values, commercial properties, and the efficiency of space utilization in production. However, only a few related investigations have been conducted in anthurium to date. In this study, an F₁ genetic segregation population containing 160 progenies was generated through hybridization between potted and cut anthurium varieties. Fifteen morphological traits were assessed and revealed substantial levels of genetic variation and widespread positive correlation. Based on specific length amplified fragment (SLAF) sequencing technology, 8171 single nucleotide polymorphism (SNP) markers were developed, and the high-density linkage map of 2202.27 cM in length distributed on 15 linkage groups was constructed successfully, with an average distance of 0.30 cM. Using the inclusive composite interval mapping (ICIM) method, 59 QTLs related to 15 key morphological traits were successfully identified, which explained phenotypic variance (PVE) ranging from 6.21% to 17.74%. Thirty-three of those associated with 13 traits were designated as major QTLs with PVE > 10%. These findings offer valuable insights into the genetic basis of quantitative traits and are beneficial for molecular marker-assisted selection (MAS) in anthurium breeding.

Bougainvillea (Bougainvillea glabra) is a perennial woody species belonging to the Nyctaginaceae family, native to South America. It is widely recognized for its brightly colored bracts and strong adaptability, and is widely cultivated as a major ornamental plant in tropical and subtropical regions. However, QTL mapping studies on morphological traits remain limited in the genus Bougainvillea, and the genetic basis underlying its key ornamental traits is still largely unclear. In this study, an F₁ segregating population was constructed using the cultivars ‘Mrs Eva White’ and ‘Formosa’ as parents, and was used for high-density genetic map construction and quantitative trait locus analysis. Fourteen leaf and thorn-related traits were investigated, with coefficients of variation ranging from 8.16% to 64.54%. Based on specific-locus amplified fragment sequencing (SLAF-seq), a total of 1,133,206 SLAF markers were developed, among which 479,488 were polymorphic. Using the inclusive composite interval mapping (ICIM) algorithm in the GACD 1.2 software, a high-density genetic linkage map was constructed for B. glabra, consisting of 17 linkage groups and 3256 markers. The genetic map spanned 1797.64 cM, with an average marker interval of 0.55 cM. A total of 22 QTLs were detected for the measured leaf and thorn traits, including 16 major QTLs with a PVE ≥ 8%. Collectively, this study identified stable genetic loci for important morphological traits and provides a valuable theoretical foundation for marker-assisted selection and genetic improvement of ornamental traits in Bougainvillea.