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Most plants are sensitive to salt-alkali stress, and the degree of tolerance to salt-alkali stress varies from different species and varieties. In order to explore the salt-alkali stress adaptability of Brassica napus , we collected the phenotypic data of 505 B. napus accessions at seedling and mature stages under control, low and high salt-alkali soil stress conditions in Inner Mongolia of China. Six resistant and 5 sensitive materials, respectively, have been identified both in Inner Mongolia and Xinjiang Uygur Autonomous Region of China. Genome-wide association studies (GWAS) for 15 absolute values and 10 tolerance coefficients (TCs) of growth and agronomic traits were applied to investigate the genetic basis of salt-alkali tolerance of B. napus. We finally mapped 9 significant QTLs related to salt-alkali stress response and predicted 20 candidate genes related to salt-alkali stress tolerance. Some important candidate genes, including BnABA4, BnBBX14, BnVTI12, BnPYL8 , and BnCRR1 , were identified by combining sequence variation annotation and expression differences. The identified valuable loci and germplasms could be useful for breeding salt-alkali-tolerant B.napus varieties. This study laid a foundation for understanding molecular mechanism of salt-alkali stress adaptation and provides rich genetic resources for the large-scale production of B. napus on salt-alkali land in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND Apart from being an oil crop, forage rape (Brassica napus) can be used to feed ruminants. The objective of this study was to investigate the effects of pelleted total mixed ration (TMR) diets with various levels of forage rape on growth performance, carcass traits, meat quality, meat nutritional value and rumen microbiota of Hu lambs, which was important for the efficient utilization of forage rape and alleviating the shortage of high‐quality forage in China. RESULTS: Lambs fed on diets with 200–400 g kg−1 forage rape had greater average daily gain (ADG) and lower feed conversion ratio (FCR) than those fed on diets with 0–100 g kg−1 of forage rape (P < 0.05). As dietary forage rape levels increased, the content of intramuscular α‐linolenic acid and a variety of amino acids in the muscle increased linearly (P < 0.05). No difference was found in carcass traits or meat quality among the dietary treatments (P > 0.05). However, the inclusion of forage rape increased the relative abundance of cellulolytic bacteria and short‐chain fatty acid producers, including Succiniclasticum, Fibrobacter and members of the Lachnospiraceae. Besides, Succiniclasticum was found to be positively correlated with the final body weight of lambs. CONCLUSION: TMR diets that included 200–400 g kg−1 forage rape could improve the growth performance of lambs, and elevated the content of intramuscular α‐linolenic acid and a variety of amino acids in the muscle, accompanied by increased abundance of cellulolytic bacteria in the rumen. [ABSTRACT FROM AUTHOR]

Brassica napus L. is a vital oil crop in China. As auxiliary tools for rapeseed breeding, transgenic technologies play a considerable role in heterosis, variety improvement, and pest resistance. Research on transgenic detection technologies is of great significance for the introduction, supervision, and development of transgenic rapeseed in China. However, the transgenic detection methods currently in use are complex and time-consuming, with low output. A single nucleotide polymorphism (SNP) chip can effectively overcome such limitations. In the present study, we collected 40 transgenic elements and designed 291 probes. The probe sequences were submitted to Illumina Company, and the Infinium chip technology was used to prepare SNP chips. In the present Brassica napus transgenic detection experiment, 84 high-quality probes of 17 transgenic elements were preliminarily screened, and genotyping effect was optimised for the probe signal value. Ultimately, a transgenic detection system for B. napus was developed. The developed system has the advantages of simple operation, minimal technical errors, and stable detection outcomes. A transgenic detection sensitivity test revealed that the probe designed could accurately detect 1% of transgenic samples and had high detection sensitivity. In addition, in repeatability tests, the CaMV35S promoter coefficient of variation was approximately 3.58%. Therefore, the SNP chip had suitable repeatability in transgene detection. The SNP chip developed could be used to construct transgenic detection systems for B. napus. [ABSTRACT FROM AUTHOR]

SUMMARY: Brassica napus is currently cultivated as an important ornamental crop in China. Flower color has attracted much attention in rapeseed genetics and breeding. Here, we characterize an orange‐flowered mutant of B. napus that exhibits an altered carotenoid profile in its petals. As revealed by map‐based cloning, the change in color from yellow to orange is attributed to the loss of BnaC09.ZEP (zeaxanthin epoxidase) and a 1695‐bp deletion in BnaA09.ZEP. HPLC analysis, genetic complementation and CRISPR/Cas9 experiments demonstrated that BnaA09.ZEP and BnaC09.ZEP have similar functions, and the abolishment of both genes led to a substantial increase in lutein content and a sharp decline in violaxanthin content in petals but not leaves. BnaA09.ZEP and BnaC09.ZEP are predominantly expressed in floral tissues, whereas their homologs, BnaA07.ZEP and BnaC07.ZEP, mainly function in leaves, indicating redundancy and tissue‐specific diversification of BnaZEP function. Transcriptome analysis in petals revealed differences in the expression of carotenoid and flavonoid biosynthesis‐related genes between the mutant and its complementary lines. Flavonoid profiles in the petals of complementary lines were greatly altered compared to the mutant, indicating potential cross‐talk between the regulatory networks underlying the carotenoid and flavonoid pathways. Additionally, our results indicate that there is functional compensation by BnaA07.ZEP and BnaC07.ZEP in the absence of BnaA09.ZEP and BnaC09.ZEP. Cloning and characterization of BnaZEPs provide insights into the molecular mechanisms underlying flower pigmentation in B. napus and would facilitate breeding of B. napus varieties with higher ornamental value. Significance Statement: Few studies have cloned petal‐pigmentation genes and revealed the molecular mechanism underlying carotenoid‐based variation in flower color. Cloning and characterization of BnaZEPs in the present study provide insights into the molecular mechanisms underlying flower pigmentation in B. napus and would facilitate breeding of B. napus varieties with higher ornamental value. [ABSTRACT FROM AUTHOR]

Brassica juncea is an important dietary vegetable cultivated and consumed in China for its edible stalks and leaves. The purple leaf mustard, which is rich in anthocyanins, is eye-catching and delivers valuable nutrition. However, the molecular mechanism involved in anthocyanin biosynthesis has not been well studied in B. juncea. Here, histological and transcriptome analyses were used to characterize the purple leaf color and gene expression profiles. Free-hand section analysis showed that the anthocyanin was mainly accumulated in the adaxial epidermal leaf cells. The anthocyanin content in the purple leaves was significantly higher than that in the green leaves. To investigate the critical genes and pathways involved in anthocyanin biosynthesis and accumulation, the transcriptome analysis was used to identify the differentially expressed genes (DEGs) between the purple and green leaves from the backcrossed BC3 segregation population in B. juncea. A total of 2,286 different expressed genes were identified between the purple and green leaves. Among them, 1,593 DEGs were up-regulated and 693 DEGs were down-regulated. There were 213 differently expressed transcription factors among them. The MYB and bHLH transcription factors, which may regulate anthocyanin biosynthesis, were up-regulated in the purple leaves. Interestingly, most of the genes involved in plant–pathogen interaction pathway were also up-regulated in the purple leaves. The late biosynthetic genes involved in anthocyanin biosynthesis were highly up-regulated in the purple leaves of B. juncea. The up regulation of BjTT8 and BjMYC2 and anthocyanin biosynthetic genes (BjC4H , BjDFR , and BjANS) may activate the purple leaf formation in B. juncea. This study may help to understand the transcriptional regulation of anthocyanin biosynthesis in B. juncea. [ABSTRACT FROM AUTHOR]

The oilseed Brassica juncea is an important crop with a long history of cultivation in India and China. Previous studies have suggested a polyphyletic origin of B. juncea and more than one migration from the primary to secondary centers of diversity. We investigated molecular genetic diversity based on 99 simple sequence repeat markers in 119 oilseed B. juncea varieties from China, India, Europe, and Australia to test whether molecular differentiation follows Vavilov's proposal of secondary centers of diversity in India and China. Two distinct groups were identified by markers in the A genome, and the same two groups were confirmed by markers in the B genome. Group 1 included accessions from central and western India, in addition to those from eastern China. Group 2 included accessions from central and western China, as well as those from northern and eastern India. European and Australian accessions were found only in Group 2. Chinese accessions had higher allelic diversity per accession (Group 1) and more private alleles per accession (Groups 1 and 2) than those from India. The marker data and geographic distribution of Groups 1 and 2 were consistent with two independent migrations of B. juncea from its center of origin in the Middle East and neighboring regions along trade routes to western China and northern India, followed by regional adaptation. Group 1 migrated further south and west in India, and further east in China, than Group 2. Group 2 showed diverse agroecological adaptation, with yellow-seeded spring-sown types in central and western China and brown-seeded autumn-sown types in India. [ABSTRACT FROM AUTHOR]

The PSII repair cycle is an important part of photosynthesis and is essential for high photosynthetic efficiency. The study of essential genes in Brassica napus provides significant potential for the improvement of gene editing technology and molecular breeding design. Previously, we identified a B. napus lethal mutant (7-521Y), which was controlled by two recessive genes (cyd1 and cyd2). BnaC06.FtsH1 was identified as a CYD1 target gene through functional verification. In the present study, we employed fine-mapping, genetic complementation, and CRISPR/Cas9 experiments to identify BnaA07.FtsH1 as the target gene of CYD2, functioning similarly to BnaC06.FtsH1. By analyzing CRISPR/Cas9 T 1 generation plants of the Westar variety, we found that the copy number of FtsH1 was positively correlated with its biomass accumulation. Transcriptome analysis of cotyledons revealed differences in the expression of photosynthesis antenna and structural proteins between the mutant and complementary seedlings. Phylogenetic and chromosome linear analyses, based on 15 sequenced cruciferous species, revealed that Brassica alone had lost FtsH5 during evolution. This may be related to the fact that FtsH5 was located at the end of chromosome ABK8 in the ancestor species. Cloning and identification of BnaFtsH1s provide a deeper understanding of PSII repair cycle mechanisms and offer new insights for the improvement of photosynthetic efficiency and molecular breeding design in B. napus., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Soil salinity is one of the most significant abiotic stresses affecting crop yield around the world. To explore the molecular mechanism of salt tolerance in rapeseed ( Brassica napus L.), the transcriptome analysis and metabolomics analysis were used to dissect the differentially expressed genes and metabolites in two rapeseed varieties with significant differences in salt tolerance; one is an elite rapeseed cultivar, Huayouza 62. A total of 103 key differentially expressed metabolites (DEMs) and 53 key differentials expressed genes (DEGs) that might be related to salt stress were identified through metabolomics and transcriptomics analysis. GO and KEGG analysis revealed that the DEGs were mainly involved in ion transport, reactive oxygen scavenging, osmotic regulation substance synthesis, and macromolecular protein synthesis. The DEMs were involved in TCA cycle, proline metabolism, inositol metabolism, carbohydrate metabolic processes, and oxidation-reduction processes. In addition, overexpression of BnLTP3 , which was one of the key DEGs, could increase tolerance to salt stress in Arabidopsis plants. This study reveals that the regulation mechanism of salt tolerance in rapeseed at the transcriptome and metabolism level and provides abundant data for further in-depth identification of essential salt tolerance genes.

The oilseed Brassica juncea is an important crop with a long history of cultivation in India and China. Previous studies have suggested a polyphyletic origin of B. juncea and more than one migration from the primary to secondary centers of diversity. We investigated molecular genetic diversity based on 99 simple sequence repeat markers in 119 oilseed B. juncea varieties from China, India, Europe, and Australia to test whether molecular differentiation follows Vavilov's proposal of secondary centers of diversity in India and China. Two distinct groups were identified by markers in the A genome, and the same two groups were confirmed by markers in the B genome. Group 1 included accessions from central and western India, in addition to those from eastern China. Group 2 included accessions from central and western China, as well as those from northern and eastern India. European and Australian accessions were found only in Group 2. Chinese accessions had higher allelic diversity per accession (Group 1) and more private alleles per accession (Groups 1 and 2) than those from India. The marker data and geographic distribution of Groups 1 and 2 were consistent with two independent migrations of B. juncea from its center of origin in the Middle East and neighboring regions along trade routes to western China and northern India, followed by regional adaptation. Group 1 migrated further south and west in India, and further east in China, than Group 2. Group 2 showed diverse agroecological adaptation, with yellow-seeded spring-sown types in central and western China and brown-seeded autumn-sown types in India.

In the present study, we have obtained one dwarf mutant (bnaC.dwf) from the Brassica napus inbred line T6 through chemical mutagen ethyl methanesulfonate (EMS). We have determined the phenotypic effects and genetic characteristics of dwarf mutant (bnaC.dwf). The dwarf mutant was insensitive to exogenous GA(3) for plant height, suggesting that it is significantly playing a crucial role in the gibberellins response pathway. Genetic analysis revealed that one recessive gene is responsible for controlling the phenotypic expression of dwarf mutant. Amplified Fragment Length Polymorphism (AFLP) technique was applied for selecting markers linked to the BnaC.DWF gene which assisted in screening of dwarf and normal individuals in the BC(4) population. We have screened 1,024 primer combinations and then identified nine AFLP markers linked to the BnaC.DWF gene. Identification and linkage of the markers were carried out by analysing 2,000 individuals from a larger population of the BC(4). Two markers EA10MC09 and EA12MC02 were located on the flanking region of the BnaC.DWF gene at a distance of 0.2 and 0.05 cM, respectively. Four AFLP markers EA09MG05, EA02MC07, EA01MC01 and EC04MC07 were successfully converted into Sequence Characterised Amplified Region markers namely SCA9G5, SCA2C7, SCA1C1 and SCC4C7. We further integrated BnaC.DWF linked Simple Sequence Repeat markers into two populations (Piquemal et al. Theor Appl Genet 111:1514-1523, 2005; Cheng et al. Theor Appl Genet 118:1121-1131, 2009). BnaC.DWF was mapped to the linkage region N18. The molecular markers developed from these investigations will greatly accelerate the selection process for developing dwarf varieties in B. napus by Marker Assisted Selection and genetic engineering.