E3 ligases promote protein ubiquitination and degradation, which regulate every aspect of eukaryotic life. The Ariadne (ARI) proteins of RBR (ring between ring fingers) protein subfamily has been discovered as a group of potential E3 ubiquitin ligases. Only a few available research studies show their role in plant adaptations processes against the external environment. Presently, the functions of ARI proteins are largely unknown in plants. Therefore, in this study, we performed genome-wide analysis to identify the ARI gene family and explore their potential importance in B. napus. A total of 39 ARI genes were identified in the B. napus genome and were classified into three subfamilies (A, B and C) based on phylogenetic analysis. The protein–protein interaction networks and enrichment analysis indicated that BnARI genes could be involved in endoreduplication, DNA repair, proteasome assembly, ubiquitination, protein kinase activity and stress adaptation. The transcriptome data analysis in various tissues provided us an indication of some BnARI genes’ functional importance in tissue development. We also identified potential BnARI genes that were significantly responsive towards the abiotic stresses. Furthermore, eight BnARI genes were identified as candidate genes for multiple agronomic traits through association mapping analysis in B. napus; among them, BnaA02g12100D, which is the ortholog of AtARI8, was significantly associated with ten agronomic traits. This study provided useful information on BnARI genes, which could aid targeted functional research and genetic improvement for breeding in B. napus.

Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (S. sclerotiorum) is the main disease threat of oilseed rape (Brassica napus), resulting in huge economic losses every year. SSR resistance manifests as quantitative disease resistance (QDR), and no gene with complete SSR resistance has been cloned or reported so far. Transcriptome analysis has revealed a large number of defense-related genes and response processes. However, the similarities and differences in the defense responses of different tissues are rarely reported. In this study, we analyzed the similarities and differences of different tissues in response to S. sclerotiorum at 24 h post inoculation (hpi) by using the published transcriptome data for respective leaf and stem inoculation. At 24 hpi, large differences in gene expression exist in leaf and stem, and there are more differentially expressed genes and larger expression differences in leaf. The leaf is more sensitive to S. sclerotiorum and shows a stronger response than stem. Different defense responses appear in the leaf and stem, and the biosynthesis of lignin, callose, lectin, chitinase, PGIP, and PR protein is activated in leaf. In the stem, lipid metabolism-mediated defense responses are obviously enhanced. For the common defense responses in both leaf and stem, the chain reactions resulting from signal transduction and biological process take the primary responsibility. This research will be beneficial to exploit the potential of different tissues in plant defense and find higher resistance levels of genotypic variability in different environments. Our results are significant in the identification of resistance genes and analysis of defense mechanisms.

Melon fruit aroma depends on the balance between ester biosynthesis and hydrolysis, yet the carboxylesterase (CXE) family responsible for hydrolysis remains uncharacterized in this crop. Here, a genome-wide identification of the CXE gene family in melon revealed 22 CmCXE genes. Phylogenetic analysis revealed that Group III members cluster with functionally validated ester-hydrolyzing CXEs from peach, tomato, and strawberry, and their expression peaks during the climacteric and post-climacteric stages—the same window when melon aroma volatiles accumulate. We further functionally characterized CmCXE7, a cold-responsive member, through subcellular localization and heterologous overexpression in tomato. CmCXE7 localized predominantly to the plasma membrane with a weak nuclear signal. Non-targeted metabolomics revealed 776 differentially accumulated metabolites (DAMs) based on VIP > 1 and p < 0.05, with 11 of 14 high-magnitude ester-related changes being downregulated. These results identify Group III genes as candidate regulators of melon ester metabolism and identify CmCXE7 as a cold-responsive CXE candidate that may participate in ester metabolism. The potential relevance of CmCXE7 to fruit ripening and postharvest storage warrants further investigation, providing a candidate gene for future functional studies and molecular breeding of melon aroma quality.