TIR1-like proteins act as auxin receptors and play essential roles in auxin-mediated plant development processes. The number of auxin receptor family members varies among species. While the functions of auxin receptor genes have been widely studied in Arabidopsis, the distinct functions of cucumber (Cucumis sativus L.) auxin receptors remains poorly understood. To further our understanding of their potential role in cucumber development, two TIR1-like genes were identified and designated CsTIR1 and CsAFB2. In the present study, tomato (Sonanum lycopersicum) was used as a model to investigate the phenotypic and molecular changes associated with the overexpression of CsTIR1 and CsAFB2. Differences in the subcellular localizations of CsTIR1 and CsAFB2 were identified and both genes were actively expressed in leaf, female flower and young fruit tissues of cucumber. Moreover, CsTIR1- and CsAFB2-overexpressing lines exhibited pleotropic phenotypes ranging from leaf abnormalities to seed germination and parthenocarpic fruit compared with the wild-type plants. To further elucidate the regulation of CsTIR1 and CsAFB2, the role of the miR393/TIR1 module in regulating cucumber fruit set were investigated. Activation of miR393-mediated mRNA cleavage of CsTIR1 and CsAFB2 was revealed by qPCR and semi-qPCR, which highlighted the critical role of the miR393/TIR1 module in mediating fruit set development in cucumber. Our results provide new insights into the involvement of CsTIR1 and CsAFB2 in regulating various phenotype alterations, and suggest that post-transcriptional regulation of CsTIR1 and CsAFB2 mediated by miR393 is essential for cucumber fruit set initiation. Collectively, these results further clarify the roles of cucumber TIR1 homologs and miR393 in regulating fruit/seed set development and leaf morphogenesis.

Parthenocarpy is an important trait for yield and quality in many plants. But due to its complex interactions with genetic and physiological factors, it has not been adequately understood and applied to breeding and production. Finding novel and effective quantitative trait loci (QTLs) is a critical step towards understanding its genetic mechanism. Cucumber (Cucumis sativus L.) is a typical parthenocarpic plant but the QTLs controlling parthenocarpy in cucumber were not mapped on chromosomes, and the linked markers were neither user-friendly nor confirmed by previous studies. Hence, we conducted a two-season QTL study of parthenocarpy based on the cucumber genome with 145 F2:3 families derived from a cross between EC1 (a parthenocarpic inbred line) and 8419 s-1 (a non-parthenocarpic inbred line) in order to map novel QTLs. Whole genome re-sequencing was also performed both to develop effective linked markers and to predict candidate genes. A genetic linkage map, employing 133 Simple Sequence Repeats (SSR) markers and nine Insertion/Deletion (InDel) markers spanning 808.1 cM on seven chromosomes, was constructed from an F2 population. Seven novel QTLs were identified on chromosomes 1, 2, 3, 5 and 7. Parthenocarpy 2.1 (Parth2.1), a QTL on chromosome 2, was a major-effect QTL with a logarithm of odds (LOD) score of 9.0 and phenotypic variance explained (PVE) of 17.0 % in the spring season and with a LOD score of 6.2 and PVE of 10.2 % in the fall season. We confirmed this QTL using a residual heterozygous line97-5 (RHL97-5). Effectiveness of linked markers of the Parth2.1 was validated in F3:4 population and in 21 inbred lines. Within this region, there were 57 genes with nonsynonymous SNPs/InDels in the coding sequence. Based on further combined analysis with transcriptome data between two parents, CsARF19, CsWD40, CsEIN1, CsPPR, CsHEXO3, CsMDL, CsDJC77 and CsSMAX1 were predicted as potential candidate genes controlling parthenocarpy. A major-effect QTL Parth2.1 and six minor-effect QTLs mainly contribute to the genetic architecture of parthenocarpy in cucumber. SSR16226 and Indel-T-39 can be used in marker-assisted selection (MAS) of cucumber breeding. Whole genome re-sequencing enhances the efficiency of polymorphic marker development and prediction of candidate genes.

Parthenocarpy is an excellent agronomic trait that enables crops to set fruit in the absence of pollination and fertilization, and therefore to produce seedless fruit. Although parthenocarpy is widely recognized as a hormone-dependent process, hormone-insensitive parthenocarpy can also be observed in cucumber; however, its mechanism is poorly understood. To improve the global understanding of parthenocarpy and address the hormone-insensitive parthenocarpy shown in cucumber, we conducted a physiological and proteomic analysis of differently developed fruits. Physiological analysis indicated that the natural hormone-insensitive parthenocarpy of ‘EC1’ has broad hormone-inhibitor resistance, and the endogenous hormones in the natural parthenocarpy (NP) fruits were stable and relatively lower than those of the non-parthenocarpic cultivar ‘8419 s-1.’ Based on the iTRAQ technique, 683 fruit developmental proteins were identified from NP, cytokinin-induced parthenocarpic (CP), pollinated and unpollinated fruits. Gene Ontology (GO) analysis showed that proteins detected from both set and aborted fruits were involved in similar biological processes, such as cell growth, the cell cycle, cell death and communication. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that ‘protein synthesis’ was the major biological process that differed between fruit set and fruit abortion. Clustering analysis revealed that different protein expression patterns were involved in CP and NP fruits. Forty-one parthenocarpy-specialized DEPs (differentially expressed proteins) were screened and divided into two distinctive groups: NP-specialized proteins and CP-specialized proteins. Furthermore, qRT-PCR and western blot analysis indicated that NP-specialized proteins showed hormone- or hormone-inhibitor insensitive expression patterns in both ovaries and seedlings. In this study, the global molecular regulation of fruit development in cucumber was revealed at the protein level. Physiological and proteomic comparisons indicated the presence of hormone-independent parthenocarpy and suppression of fruit abortion in cucumber. The proteomic analysis suggested that hormone-independent parthenocarpy is regulated by hormone-insensitive proteins such as the NP-specialized proteins. Moreover, the regulation of fruit abortion suppression may be closely related to protein synthesis pathways.

The rose (Rosa chinensis), with its rich color variations and elegant form, holds a significant position in the global floriculture industry, where the color of its petals and the content of anthocyanins are crucial for enhancing the plant’s ornamental value and market competitiveness. Nevertheless, the precise roles of the GST gene family in roses, especially regarding their participation in anthocyanin transport and the modulation of petal color, remain poorly elucidated. In the present investigation, we identified 83 rose glutathione S-transferase (GST) genes through whole-genome analysis. The identification and functional analysis of RcGSTF2 were conducted exclusively in the ‘Old Blush’ cultivar of Rosa chinensis. We employed bioinformatics, tissue expression analysis, subcellular localization, and transient expression validation to explore the function of the RcGSTF2 gene in anthocyanin transport and accumulation. We found that RcGSTF2 is closely related to anthocyanin-associated GSTs and demonstrated a conserved domain with high sequence similarity. Molecular docking analysis revealed potential binding modes between RcGSTF2 and cyanidin-3,5-diglucoside, suggesting a role in anthocyanin transport. Subcellular localization indicated that RcGSTF2 is associated with the cell membrane. Overexpression of RcGSTF2 in rose plants significantly increased anthocyanin accumulation, while silencing RcGSTF2 reduced anthocyanin content, highlighting its crucial role in regulating anthocyanin accumulation. This research investigates the functions of the GST gene family in roses, laying the groundwork for developing more colorful and resilient rose cultivars, with the functional analysis of RcGSTF2 being a key contribution to the floriculture industry’s genetic enhancement efforts.

Luffa is a genus of tropical and subtropical vines in the Cucurbitaceae family, recognized as an important cultivated commercial vegetable. However, the seeds of the luffa species are considered hard-seeded, and the processes governing seed germination remain understudied. The 9-cis-epoxycarotenoid dioxygenase (NCED) genes, which are critical for seed germination, have not been well characterized in Luffa. In this study, we identified four LaNCED genes in Luffa acutangula and four LcNCED genes in Luffa cylindrica, distributed across four chromosomes in each species. Phylogenetic analysis classified these genes into two subgroups. Gene structure and motif composition analyses revealed both similarities and differences among the NCEDs. Cis-element analysis further revealed that these NCEDs may be involved in growth regulation by modulating the phytohormonal network and responding to stress stimuli. Expression profiling of LcNCED genes during seed germination showed a decrease in LcNCED2 levels, coinciding with an increase in α-amylase activity throughout the germination process. Subcellular localization assays demonstrated that LcNCED2 is localized in the chloroplast. Furthermore, transient overexpression of LcNCED2 in tobacco leaves led to a significant increase in ABA content. Our findings provide a comprehensive genomic characterization of the NCED family in Luffa cylindrica and Luffa acutangula and reveal the functional role of LcNCED2 in regulating ABA levels, which may play a critical role in seed germination.

White-fruited bitter melon is a rare species of Momordica charantia L., valued for its pearl-like white pericarp. However, limited research is available regarding its supporting cultivation techniques and fruit quality. Two-season field trials were performed using ‘Kuzhongle’ as scion to evaluate the applicability of luffa rootstocks and seasonal variation in rootstock-mediated effects. Three luffa inbred lines (SS07, SS11 and SS26) were screened in spring, and the superior SS26 was further compared with the commercial rootstock ‘Yinzhen No.1’ in autumn. All rootstocks increased stem diameters, shortened internodes and promoted female flower formation in spring, but their effects on fruit quality varied among genotypes. SS26 exhibited the highest survival rate and significantly enhanced soluble solid content, water content, crude protein content and vitamin C content, while reducing crude fiber content and titratable acidity content. Seasonal comparison revealed consistent quality-modulating effects of SS26 across seasons, except for crude fiber, with a comprehensive performance comparable to the commercial rootstock. Overall, luffa rootstocks consistently modulate vegetative and flowering traits within a season, whereas their impacts on fruit quality show genotypic differences. SS26 exhibits stable and superior grafting performance, providing important material support for bitter melon rootstock breeding research.