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Background and aims: Magnesium (Mg) deficiency impacts many metabolic processes in Brassica napus (B. napus), leading to yield loss. However, the mechanism of Mg2+ uptake and translocation in B. napus remains unknown. Methods: After screening 39 genotypes of B. napus under Mg-deficient conditions, the cultivars P160 and P153 were selected according to their Mg transfer factor (TF) from root to shoot. We further characterized these two genotypes under Mg-deficiency by analyzing chlorophyll concentration, malondialdehyde and peroxidase activity, and reducing sugar concentration in leaves. Additionally, we performed transcriptomics and qRT-PCR assays on P153 and P160 shoots and roots. The identified functional genes involved in Mg transport were characterized by functional assays in yeast and Arabidopsis mutants. Results: The physiological analysis revealed that P160 (Mg tolerance cultivar; Mg-T) is more tolerant than P153 (Mg sensitive cultivar; Mg-S) under magnesium-deficient environments. Transcriptomics and qRT-PCR assays revealed that transcript levels of BnMGT1–2 and BnMGT6–1 were more significantly up-regulated in the shoot of Mg-T cultivar than that of the Mg-S cultivar under Mg limitation. Functional assays of BnMGT1–2 and BnMGT6–1 reveals that BnMGT1–2 and BnMGT6–1 are the two main functional Mg transporters mediating Mg translocation from root to shoot under low Mg conditions. Conclusion: Mg-T is more efficient in the translocation of Mg from root to shoot than Mg-S. BnMGT1–2 and BnMGT6–1 should be the two main Mg transporters associated with Mg translocation under Mg deficiency condition, which caused the different Mg efficiency between the Mg-T and Mg-S. [ABSTRACT FROM AUTHOR]

Aims: Cadmium (Cd) is the most widespread toxic heavy metal to plant growth. As the second leading oil crop, some genotypes of Brassica napus (B. napus) are potential Cd accumulators. However, the Cd translocation mechanism from root to shoot in B. napus in response to Cd toxicity remains unknown. Methods: In the present study, a couple of B. napus genotypes with contrasting Cd uptake and root-to-shoot translocation abilities, named P78 (the high Cd accumulator, HC) and P72 (the low Cd accumulator, LC), were chosen from 39 B. napus genotypes with various Cd accumulation features. Results: Physiological comparison of P78 and P72 reveals that P72 is more sensitive to Cd toxicity than P78. With genomic resequencing, transcriptomics and qRT-PCR assay, BnNramp2;1 and BnNramp4;2 were focused with highly upregulation in shoot of P78 under Cd treatment condition. Furthermore, BnNramp2;1 and BnNramp4;2 can successfully complement the function of tonoplast localized Cd transporter YCF1. And when BnNramp2;1 and BnNramp4;2 were transferred in Arabidopsis atnramp mutants, the transgenic plants showed better growth rate than mutants under higher Cd stress conditions. Conclusions: The results reveals that BnNramp2;1 and BnNramp4;2 were two main Cd transporters associated with enhanced root-to-shoot translocation and accumulation of Cd in shoot of B. napus. [ABSTRACT FROM AUTHOR]

Background: Increasing seed oil content is one of the most important targets for rapeseed (Brassica napus) breeding. However, genetic mechanisms of mature seed oil content in Brassica napus (B. napus) remain little known. To identify oil content-related genes, a genome-wide association study (GWAS) was performed using 588 accessions. Results: High-throughput genome resequencing resulted in 385,692 high-quality single nucleotide polymorphism (SNPs) with a minor allele frequency (MAF) > 0.05. We identified 17 loci that were significantly associated with seed oil content, among which 12 SNPs were distributed on the A3 (11 loci) and A1 (one loci) chromosomes, and five novel significant SNPs on the C5 (one loci) and C7 (four loci) chromosomes, respectively. Subsequently, we characterized differentially expressed genes (DEGs) between the seeds and silique pericarps on main florescences and primary branches of extremely high- and low-oil content accessions (HO and LO). A total of 64 lipid metabolism-related DEGs were identified, 14 of which are involved in triacylglycerols (TAGs) biosynthesis and assembly. Additionally, we analyzed differences in transcription levels of key genes involved in de novo fatty acid biosynthesis in the plastid, TAGs assembly and lipid droplet packaging in the endoplasmic reticulum (ER) between high- and low-oil content B. napus accessions. Conclusions: The combination of GWAS and transcriptome analyses revealed seven candidate genes located within the confidence intervals of significant SNPs. Current findings provide valuable information for facilitating marker-based breeding for higher seed oil content in B. napus. [ABSTRACT FROM AUTHOR]