Cuticular wax is a mixture of very long chain fatty acids (VLCFAs) and their derivatives, which determines vital roles for plant growth. In cabbage, the cuticular wax content of leaf blades is an important trait influencing morphological features of the head. Understanding the molecular basis of cuticular wax biosynthesis can help breeders develop high quality cabbage varieties. Here, we characterize a cabbage non-wax glossy (nwgl) plant, which exhibits glossy green phenotype. Cryo-scanning electron microscope analysis showed abnormal wax crystals on the leaf surfaces of nwgl plants. Cuticular wax composition analyzed by GC-MS displayed severely decreased in total wax loads, and individual wax components in nwgl leaves. We delimited the NWGL locus into a 99-kb interval between the at004 marker and the end of chromosome C08 through fine mapping. By high-throughput RNA sequencing, we identified 1247 differentially expressed genes (DEGs) and 148 differentially expressed lncRNAs in nwgl leaves relative to the wild-type. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the DEGs and cis-regulated target genes for differentially expressed lncRNAs were significantly enriched in wax and lipid biosynthetic or metabolic processes. Our results provide the novel foundation to explore the complex molecular basis of cuticular wax biosynthesis.

Cabbage is often affected by an adverse environment and pathogens during its growth, resulting in a decline in yield and quality. Mitogen-activated protein kinases (MAPKs) play crucial roles in the development process, hormones, abiotic and biotic stresses, and cell division. So far, MAPKs have been characterized in various species. However, no systematic analysis of the MAPK family in cabbage has been performed. A total of 24 BoMAPK genes were identified and renamed according to Arabidopsis homologs; they were unevenly distributed on nine chromosomes. According to the conserved domain and phylogenetic relationship, BoMAPKs were divided into four subgroups, of which three belonged to subgroup A, four to subgroup B, three to subgroup C, and fourteen to subgroup D, respectively. There were 13 segmental duplication events in the cabbage genome. The Ka/Ks ratios for duplicated gene pairs of the MAPK family were less than 0.2, indicating that these BoMAPK genes have undergone purification selection in evolution. There were various cis-acting elements associated with stress, hormones, and development found in the promoter regions of most BoMAPK genes. Transcriptome data showed a high expression of BoMAPK3, BoMAPK4.1, and BoMAPK6.1 genes in various tissues. BoMAPK17.2, BoMAPK20.1 and BoMAPK20.2 were significantly induced by Plasmodiophora brassicae, as evidenced in the quantitative PCR (RT-qPCR) analysis, revealing their enormous potential to regulate stress response. RT-qPCR results showed how the transcriptional levels of BoMAPK genes varied substantially under abiotic stress at different time points. These analysis results provide a reference to further explore the function and evolution of BoMAPK genes in cabbage.

Identification and Expression Profiles of the WRKY Gene Family in Pecan ( Carya illinoinensis )

Clubroot disease, caused by the pathogen Plasmodiophora brassicae, is a serious disease that poses a critical threat to cabbage production. However, the molecular mechanism of the microRNAs (miRNAs) involved in the cabbage’s response to P. brassicae infection remains to be elucidated. Here, the mRNA and miRNA expression profiles of cabbage in response to a P. brassicae infection were analyzed. In the transcriptome analysis, 2217 and 5552 differentially expressed genes (DEGs) were identified at 7d and 21d after inoculation, which were enriched in MAPK signaling, plant–pathogen interaction, plant hormone signal transduction, and phenylpropanoid biosynthesis pathways. BolC02g057640.2J, BolC09g006890.2J, BolC02g013230.2J, BolC06g006490.2J, BolC03g052660.2J, BolC07g052580.2J, and BolC04g044910.2J were predicted to be significantly involved in the defense response or plant–pathogen interaction through co-expression network analysis. Small RNA data analysis identified 164 miRNAs belonging to 51 families. miR1515, miR166, miR159, and miR9563 had the greatest number of members among the miRNA families. Integrated analysis revealed 23 miRNA–mRNA interactions related to a P. brassicae infection. The target genes of differentially expressed miRNAs (DEMs) revealed the NAC, ARF, TCP, and SPL transcription factor members that probably participate in the defense response. This study provided new insights into the miRNA-involved regulatory system during the process of disease infection with P. brassicae in cabbage.