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Enhancing photosynthetic efficiency is a major goal for improving crop yields under agricultural field conditions and is associated with chloroplast biosynthesis and development. In this study, we demonstrate that Golden2-like 1a (BnGLK1a) plays an important role in regulating chloroplast development and photosynthetic efficiency. Overexpressing BnGLK1a resulted in significant increases in chlorophyll content, the number of thylakoid membrane layers and photosynthetic efficiency in Brassica napus, while knocking down BnGLK1a transcript levels through RNA interference (RNAi) had the opposite effects. A yeast two-hybrid screen revealed that BnGLK1a interacts with the abscisic acid receptor PYRABACTIN RESISTANCE 1-LIKE 1–2 (BnPYL1–2) and CONSTITUTIVE PHOTOMORPHOGENIC 9 SIGNALOSOME 5A subunit (BnCSN5A), which play essential roles in regulating chloroplast development and photosynthesis. Consistent with this, BnGLK1a-RNAi lines of B. napusdisplay hypersensitivity to the abscisic acid (ABA) response. Importantly, overexpression of BnGLK1a resulted in a 10% increase in thousand-seed weight, whereas seeds from BnGLK1a-RNAi lines were 16% lighter than wild type. We propose that BnGLK1a could be a potential target in breeding for improving rapeseed productivity. Our results not only provide insights into the mechanisms of BnGLK1a function, but also offer a potential approach for improving the productivity of Brassicaspecies.

Rapeseed (Brassica napus) is an oil crop grown worldwide, making it a key plant species in molecular breeding research. However, the complexity of its polyploid genome increases sequencing costs and reduces sequencing accuracy. Target capture coupled with high-throughput sequencing is an efficient approach for detecting genetic variation at genomic regions or loci of interest. In this study, 588 resequenced accessions of rapeseed were used to develop a target capture sequencing SNP genotyping platform named BnaPan50T. The platform comprised 54,765, with 54,058 resequenced markers from the pan-genome, and 855 variant trait-associated markers for 12 agronomic traits. The capture quality of BnaPan50T was demonstrated well in 12 typical accessions. Compared with a conventional genotyping array, BnaPan50T has a high SNP density and a high proportion of SNPs in unique physical positions and in annotated functional genes, promising wide application. Target capture sequencing and whole-genome resequencing in 90 doubled-haploid lines yielded 60% specificity, 78% uniformity within tenfold coverage range, and 93% genotyping accuracy for the platform. BnaPan50T was used to construct a genetic map for quantitative trait loci (QTL) mapping, identify 21 unique QTL, and predict several candidate genes for yield-related traits in multiple environments. A set of 132 core SNP loci was selected from BnaPan50T to construct DNA fingerprints and germplasm identification resources. This study provides genomics resources to support target capture sequencing, genetic analysis and genomic breeding of rapeseed.

Yellow seed trait is a desirable characteristic with potential for increasing seed quality and commercial value in rapeseed, and anthocyanin and proanthocyanidins (PAs) are major seed-coat pigments. Few transcription factors involved in the regulation of anthocyanin and PAs biosynthesis have been characterized in rapeseed. In this study, we identified a transcription factor gene BnbHLH92a(BnaA06T0441000ZS) in rapeseed. Overexpressing BnbHLH92aboth in Arabidopsisand in rapeseed reduced levels of anthocyanin and PAs. Correspondingly, the expression profiles of anthocyanin and PA biosynthesis genes (TT3, BAN, TT8, TT18, and TTG1) were shown by quantitative real-time PCR to be inhibited in BnbHLH92a-overexpressing Arabidopsisseeds, indicating that BnbHLH92arepresses the anthocyanin and PA biosynthesis pathway in Arabidopsis. BnbHLH92a physically interacts with the BnTTG1 protein and represses the biosynthesis of anthocyanins and PAs in rapeseed. BnbHLH92a also binds directly to the BnTT18promoter and represses its expression. These results suggest that BnbHLH92a is a novel upstream regulator of flavonoid biosynthesis in B. napus.

Rapeseed (Brassica napus) is one of the most important oil crops worldwide; however, drought seriously curtails its growth and productivity. Identifying drought-tolerant germplasm is an efficient strategy for addressing water shortages. Here, we phenotyped a panel of 264 B. napusaccessions at full-bloom stage using water loss ratio (WLR) as drought-tolerant index. It identified 8 low-WLR and 6 high-WLR accessions, regarded as drought-tolerant and drought-sensitive, respectively. Comparing with drought-sensitive accessions at the seedling stage, drought-tolerant accessions had shown better performance in maintaining fresh and dry weights, and performed the higher expression of drought-induced marker genes under drought stress. Subsequently, a total of 139 SNPs (single nucleotide polymorphisms) were identified associated with the WLR using a genome-wide association study (GWAS) among 264 B. napusaccessions, with the largest number SNPs at chromosome A10, and 13 SNPs significantly were associated with the WLR (–log10(p-value) > 6). Furthermore, 4 putative candidate genes (BnaC09.RPS6, BnaC09.MATE, BnaA10.PPD5and BnaC09.Histone) were screened involving in drought tolerance in B. napus. Together, our results highlight the WLR's importance in drought tolerance and establish the foundation for improving WLR-associated drought tolerance in rapeseed.

The ubiquity of microplastics in aquatic and terrestrial environments and related ecological impacts have gained global attention. Microplastics have been detected in table salt, drinking water, and air, posing inevitable human exposure risk. However, rigorous analytical methods for detection and characterization of microplastics remain scarce. Knowledge about the potential adverse effects on human health via dietary and respiratory exposures is also limited. To address these issues, we reviewed 46 publications concerning abundances, potential sources, and analytical methods of microplastics in table salt, drinking water, and air. We also summarized probable translocation and accumulation pathways of microplastics within human body. Human body burdens of microplastics through table salt, drinking water, and inhalation were estimated to be (0–7.3)×104, (0–4.7)×103, and (0–3.0)×107items per person per year, respectively. The intake of microplastics via inhalation, especially via indoor air, was much higher than those via other exposure routes. Moreover, microplastics in the air impose threats to both respiratory and digestive systems through breathing and ingestion. Given the lifetime inevitable exposure to microplastics, we urgently call for a better understanding of the potential hazards of microplastics to human health.

The high levels of secondary metabolites in rapeseed play important roles in determining the oil quality and feeding value. Here, we characterized the metabolic profiles in seeds of various yellow- and black-seeded rapeseed accessions. Two hundred and forty-eight features were characterized, including 31 phenolic acids, 54 flavonoids, 24 glucosinolates, 65 lipid compounds, and 74 other polar compounds. The most abundant phenolic acids and various flavonoids (epicatechin, isorhamnetin, kaempferol, quercetin, and their derivatives) were widely detected and showed significant differences in distribution between the yellow- and black-seeded rapeseed. Furthermore, the related genes (e.g., BnTT3, BnTT18, BnTT10, BnTT12, and BnBAN) involved in the proanthocyanidin pathway had lower expression levels in yellow-seeded rapeseed, strongly suggesting that the seed coat color could be mainly determined by the levels of epicatechin and their derivatives. These results improve our understanding of the primary constituents of rapeseed and lay the foundation for breeding novel varieties with a high nutritional value.

Higher amounts of cuticular wax in plants have been associated with improved plant stress tolerance and increased potential for industrial use. In this study, orthologs of KCS1and CER1in Arabidopsis, designated BnKCS1-1, BnKCS1-2, and BnCER1-2, were isolated from Brassica napus. Transcription of BnKCS1-1and BnKCS1-2in B. napuswere induced by abscisic acid (ABA) and drought treatment, while transcription of BnCER1-2was induced only by drought treatment. All three gene transcripts decreased significantly when plants were treated with methyl jasmonate (MeJA) or subjected to cold stress. Overexpression of BnKCS1-1, BnKCS1-2, and BnCER1-2under the control of the CaMV35S promoter led to a significant increase in cuticular wax on transgenic B. napusleaves. BnKCS1-1and BnKCS1-2overexpression led to similar differences from non-transformed plants, with significantly higher levels of aldehydes (C29and C30), alkanes (C28, C29, and C31) and secondary alcohols (C28and C29), and a significantly lower level of C29ketone. Overexpression of BnCER1-2led to an increase in alkanes (C27, C28, C29, and C31), a decrease in secondary alcohols (C28and C29), and insignificant changes in other wax components. Scanning electron microscopy revealed that overexpression of BnKCS1-1, BnKCS1-2, and BnCER1-2in B. napusresulted in a higher density of wax crystals on the leaf surface than observed in non-transformed plants. Transgenic plants showed a reduced rate of water loss and increased drought tolerance compared to non-transformed plants. These results suggest that BnKCS1-1, BnKCS1-2, and BnCER1-2gene products can modify the cuticular wax of B. napus. Changing cuticular waxes using transgenic approaches is a new strategy for genetic improvement of plant drought tolerance and provides an opportunity for development of B. napusas a surface-wax crop.

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.ocsci.2021.01.001. The duplicate article has therefore been withdrawn.

Abstract: The adenomatous polyposis coli (APC) gene has been shown to be involved in genetic instability and to be downregluated in several human carcinomas. The chromosome locus of APC, 5q21-22, is frequently deleted in colorectal cancers (CRCs). The functional impact of such regions needs to be extensively investigated in large amount of clinical samples. Case-matched tissues of CRC and adjacent normal epithelium (n = 134) were included in this study. Quantitative PCR was carried out to examine the copy number as well as mRNA expression of APC gene in colorectal malignancies. Our results showed that copy number deletions of APC were present in a relatively high percentage of colorectal cancer samples (26.1%, 35 out of 134). There was a positive correlation between copy number decrease of APC and tumor progression in CRCs. Furthermore, copy number loss of APC was correlated with decreased mRNA expression. However, mRNA levels of APC were also impaired in CRC samples with unaltered copy numbers, indicating that sporadic CRCs exhibit different mechanisms of APC regulation.

The leaf is the main organ for rapeseed photosynthesis, and its morphology influences photosynthetic efficiency and supports increased planting density and yield. However, the molecular regulatory mechanism of leaf morphology in Brassica napusis poorly understood, restricting progress in breeding for the trait. We describe a novel dominant mutation, curly leaf 1(cl1), which confers uneven dorsal–ventral axis development, irregular cellular structure and influenced gravitropic response in the seedling stage. The CL1locus was mapped to a 1.573-Mb interval on chromosome A05 using simple sequence repeat (SSR) markers, and co-segregated with the phenotype of plants in the curly F2population. A substitution (P62S) was identified in the highly conserved degron motif (GWSPV) of the IAA2 protein in the cl1mutant, and the P62S substitution impaired the interaction between IAA2 and TIR1 in the presence of auxin, influencing auxin signaling. The P62S substitution-induced curly leaf phenotype was verified by ectopic expression of BnaA05.iaa2in Arabidopsisand B. napus. Our findings explain the function of IAA2in rapeseed, providing a foundation for future investigation of auxin signaling and the mechanisms underlying leaf development in B. napus.

A narrow genetic base has hindered improvement of Brassica juncea(AjAjBjBj). In this study, large-scale genomic components were introduced from diploid ancestor species into modern B. junceausing a digenomic hexaploid strategy. The hexaploids AjAjArArBjBjand AjAjBjBjBnBnwere first developed from B. juncea × B. rapa(ArAr) and B. juncea × B. nigra(BnBn), and then crossed with dozens of B. nigraand B. rapa, respectively. Both types of hexaploid showed high pollen fertility and moderate seed set throughout the S1to S3generations, and could be crossed with diploid progenitor species under field conditions, in particular for the combination of AjAjBjBjBnBn × B. rapa. Thirty AjArBnBj-type and 31 AjArBnBj-type B. juncearesources were generated, of which the AjArBnBjtype showed higher fertility. Of these new-type B. juncearesources, 97 individual plants were genotyped with 42 simple sequence repeat markers, together with 16 current B. junceaaccessions and 30 hexaploid plants. Based on 180 polymorphic loci, the new-type B. juncearesources and current B. junceawere separated clearly into distinct groups, with large genetic distance between the new-type B. juncearesources and current B. juncea. Our study provides a novel approach to introducing large-scale genomic components from diploid ancestor species into B. juncea.

Brassicacrops, which are of worldwide importance, provide various oil, vegetable and ornamental products, as well as feedstocks for animal husbandry and biofuel industry. Cinnamoyl-CoA reductase (CCR) is the entry point to the lignin pathway and a crucial locus in manipulation of associated traits, but CCR-associated metabolism and traits in Brassicacrops have remained largely unstudied except in Arabidopsis thaliana. We report the identification of 16 CCRgenes from Brassica napusand its parental species B. rapaand B. oleracea. The BnCCR1and BnCCR2subfamilies displayed divergent organ-specificity and participation in the yellow-seed trait. Their functions were dissected via overexpression of representative paralogs in B. napus. BnCCR1was expressed preferentially in G- and H-lignin biosynthesis and vascular development, while BnCCR2was expressed in S-lignin biosynthesis and interfascicular fiber development. BnCCR1showed stronger effects on lignification-related development, lodging resistance, phenylpropanoid flux control, and seed coat pigmentation, whereas BnCCR2showed a stronger effect on sinapate biosynthesis. BnCCR1upregulation delayed bolting and flowering time, while BnCCR2upregulation weakened the leaf vascular system in consequence of suppressed G-lignin accumulation. BnCCR1and BnCCR2were closely but almost oppositely linked with glucosinolate metabolism via inter-pathway crosstalk. We conclude that BnCCR1and BnCCR2subfamilies offer great but differing potential for manipulating traits associated with phenylpropanoids and glucosinolates. This study reveals the CCR1–CCR2divergence in Brassicaceae and offers a resource for rapeseed breeding for lodging resistance, yellow-seed traits, and glucosinolate traits.

Inflammatory mechanisms are important in stroke risk, and genetic variation in components of the inflammatory response has been implicated as risk factors for stroke. We tested the inflammatory gene polymorphisms and their association with ischemic stroke in Chinese Han population.