Nitrate (NO₃⁻) and ammonium (NH₄⁺) are the main inorganic nitrogen (N) sources absorbed by oilseed rape, a plant that exhibits genotypic differences in N efficiency. In our previous study, the biomass, N accumulation, and root architecture of two oilseed rape cultivars, Xiangyou 15 (high N efficiency, denoted “15”) and 814 (low N efficiency, denoted “814”), were inhibited under NH₄⁺ nutrition, though both cultivars grew normally under NO₃⁻ nutrition. To gain insight into the underlying molecular mechanisms, transcriptomic changes were investigated in the roots of 15 and 814 plants subjected to nitrogen-free (control, CK), NO₃⁻ (NT), and NH₄⁺ (AT) treatments at the seedling stage. A total of 14,355 differentially expressed genes (DEGs) were identified. Among the enriched Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway categories of these DEGs, carbohydrate metabolism, lipid metabolism, protein metabolism, and cell wall biogenesis were inhibited by AT treatment. Interestingly, DEGs such as N transporters, genes involved in N assimilation and CESA genes related to cellulose synthase were also mostly downregulated in the AT treatment group. This downregulation of genes related to crucial metabolic pathways resulted in inhibition of oilseed rape growth after AT treatment.

Clubroot significantly affects plants of the Brassicaceae family and is one of the main diseases causing serious losses in B. napus yield. Few studies have investigated the clubroot-resistance mechanism in B. napus. Identification of clubroot-resistant genes may be used in clubroot-resistant breeding, as well as to elucidate the molecular mechanism behind B. napus clubroot-resistance. We used three B. napus transcriptome samples to construct a transcriptome sequencing library by using Illumina HiSeq™ 2000 sequencing and bioinformatic analysis. In total, 171 million high-quality reads were obtained, containing 96,149 unigenes of N50-value. We aligned the obtained unigenes with the Nr, Swiss-Prot, clusters of orthologous groups, and gene ontology databases and annotated their functions. In the Kyoto encyclopedia of genes and genomes database, 25,033 unigenes (26.04%) were assigned to 124 pathways. Many genes, including broad-spectrum disease-resistance genes, specific clubroot-resistant genes, and genes related to indole-3-acetic acid (IAA) signal transduction, cytokinin synthesis, and myrosinase synthesis in the Huashuang 3 variety of B. napus were found to be related to clubroot-resistance. The effective clubroot-resistance observed in this variety may be due to the induced increased expression of these disease-resistant genes and strong inhibition of the IAA signal transduction, cytokinin synthesis, and myrosinase synthesis. The homology observed between unigenes 0048482, 0061770 and the Crr1 gene shared 94% nucleotide similarity. Furthermore, unigene 0061770 could have originated from an inversion of the Crr1 5'-end sequence.

A study on physiological, biochemical and differential protein expression response mechanisms was conducted by with two breeds of winter rapeseed (Brassica rapa L.), DR-7 (drought resistant) and Tianyou 5 (drought sensitive), under drought stress. The results showed that leaves in winter rapeseed wilted, the edge of the leaf gradually withered, the relative water content in the leaf decreased and the contents of osmotic regulatory substances and malondialdehyde in the leaf rose with increasing drought intensity due to cell membrane damage under dry conditions. Twenty-three differentially expressed proteins (DEPs) were selected by two-dimensional gel electrophoresis with liquid chromatography mass spectrometry (LC-MS) analysis under drought stress; These proteins were related to lipid metabolism, protein/amino acid metabolism, metabolic pathways, linoleic acid metabolism, oxidative phosphorylation processes, response to stress, energy metabolism and photosynthesis. Among the DEPs, three were involved in ATP metabolism and three in fatty acid metabolism. Furthermore, with increasing drought intensity, the activities of Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase in leaves gradually decreased; The content of saturated fatty acids (SFAs) in membrane system significantly increased, which together with the enzyme activity is crucial to cell metabolism; And polyunsaturated fatty acids (PUFAs) slightly increased. According to the results, the damage in membrane system due to SFAs was alleviated by the increase of PUFA content, increasing the ability of winter rapeseed to resist drought. Overall, the increase of osmotic regulatory substances contents and the decrease in osmotic potential in winter rapeseed due to drought stress improve water absorption and regulate the expression of related proteins. thus improving resistance to drought. Increasing of PUFA content were advantageous to the function of the membrane-bound enzyme ATPase.