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[学术文献 ] Comparative analysis of drought responsive transcriptome in Brassica napus genotypes with contrasting drought tolerance under different potassium levels 进入全文
Euphytica
Drought is a major limiting factor of Brassica napus (rapeseed) and potassium (K) plays important roles in rapeseed drought tolerance. Previous studies have reported that rapeseed cultivars characterized by different K status showed contrasting drought tolerance. However, the molecular mechanism underlying drought tolerance remains unclear. In this study, comparative transcriptome analysis was conducted between drought-tolerant cultivar Youyan57 and drought-sensitive cultivar Chuanyou36 exposed to PEG6000 simulated drought stress with two K levels (1.0 and 0.01 mM K2SO4, referred to NK and LK, respectively). A total of 1689 differentially expressed genes (DEGs) were identified at NK. DEGs involved in photosynthesis, glutathione biosynthesis, IAA signal transduction were up-regulated in Youyan57 at NK. By contrast, the down-regulated DEGs were significantly enriched in biosynthesis of amino acids, cysteine and methionine metabolism and glucosinolate biosynthesis. Transcription profile was affected seriously at LK treatment since only 1050 DEGs were identified. DEGs involved in biosynthesis of amino acids reduced largely. Furthermore, the conspicuous up-regulation of protein phosphatase 2 C in Chuanyou36 could lead to more severe drought stress at LK, which negatively participated in abscisic acid (ABA) signal transduction. Taken together, the comparative transcriptome analysis identified a set of drought-regulated genes involved in several pathways, and provided important information about molecular mechanisms underlying rapeseed drought tolerance.
[学术文献 ] Molecular Markers for Detecting Inflorescence Size of Brassica oleracea L. Crops and B. oleracea Complex Species (n = 9) Useful for Breeding of Broccoli (B. oleracea var. italica) and Cauliflower (B. oleracea var. botrytis) 进入全文
Plants
The gene flow from Brassica oleracea L. wild relatives to B. oleracea vegetable crops have occurred and continue to occur ordinarily in several Mediterranean countries, such as Sicily, rep-resenting an important hot spot of diversity for some of them, such as broccoli, cauliflower and kale. For detecting and for exploiting the forgotten alleles lost during the domestication processes of the B. oleracea crops, attention has been pointed to the individuation of specific markers for in-dividuating genotypes characterized by hypertrophic inflorescence traits by the marker assisted selection (MAS) during the first plant growing phases after the crosses between broccoli (B. oleracea var. italica)/cauliflower (B. oleracea var. botrytis) with B. oleracea wild relatives (n = 9), reducing the cultivation and evaluation costs. The desired traits often found in several B. oleracea wild relatives are mainly addressed to improve the plant resistance to biotic and abiotic stresses and to increase the organoleptic, nutritive and nutraceutical traits of the products. One of the targeted traits for broccoli and cauliflower breeding is represented by the inflorescences size as is documented by the domestication processes of these two crops. Based on the previous results achieved, the numerical matrix, obtained utilizing five simple sequence repeats (SSRs), was analyzed to assess the relationship among the main inflorescence characteristics and the allelic variation of the SSRs loci analyzed (BoABI1, BoAP1, BoPLD1, BoTHL1 and PBCGSSRBo39), both for the Brassica oleracea and B. oleracea wild relatives (n = 9) accessions set. The main inflorescence morphometric characteristics, such as weight, height, diameter, shape, inflorescence curvature angle and its stem diameter, were registered before the flower anthesis. We analyzed the correlations among the allelic variation of the SSRs primers utilized and the inflorescence morphometric characteristics to individuate genomic regions stimulating the hypertrophy of the reproductive organ. The relationships found explain the diversity among B. oleracea crops and the B. oleracea complex species (n = 9) for the inflorescence size and structure. The individuated markers allow important time reduction during the breeding programs after crossing wild species for transferring useful biotic and abiotic resistances and organoleptic and nutraceutical traits to the B. oleracea crops by MAS.
[学术文献 ] Genetic Dissection and Germplasm Selection of the Low Crude Fiber Component in Brassica napus L. Shoots 进入全文
Foods
Background: Brassica napus is one of the most important oil crops in the world, and B. napus shoots are nutrient-rich fresh vegetables. The crude fiber (CF) component is one of the most important factors affecting the taste quality of B. napus shoots, but the factors underlying the desirable low-CF trait remain poorly understood. Methods: In this study, a high-density single-nucleotide polymorphism (SNP) map was used to map quantitative trait loci (QTLs) for five CF-related traits in a recombinant inbred population. Results: A total of 49 QTLs were obtained in four environments, including eleven, twelve, eight, twelve and six QTLs for content of neutral detergent fiber, acid detergent fiber, acid detergent lignin, hemicellulose and cellulose, respectively. The phenotypic variation explained by single QTL ranged from 4.62% to 14.76%. Eight of these QTLs were further integrated into four unique QTLs, which controlled two different traits simultaneously. Five CF-component-related candidate genes were identified, among which BnaC03g07110D and BnaC07g21271D were considered to be the most likely candidate genes. In addition, five lines with low CF content were selected, which can be used as excellent germplasm resources in breeding. Conclusions: The QTLs identified in this study will contribute to our understanding of the genetic mechanism of CF and can be used as targets for reducing CF content in B. napus shoots. In addition, this study also provided excellent germplasm resources for low CF content breeding.
[学术文献 ] Genetic Diversity Analysis of Non-Heading Chinese Cabbage of Resistance to Clubroot Disease Based on SNP Molecular Markers 进入全文
Agronomy
Clubroot disease is a kind of soil-borne disease that seriously infects Brassica species. In this study, we collected 121 varieties of non-heading Chinese cabbages. In order to better understand the genetic variation and to screen suitable clubroot disease-resistant parental material, we re-sequenced them to examine the population genetic structure, population genetic diversity, population differenti-ation index, and selective sweep based on SNPs. The mapping rate with the reference genome was high, and data quality analysis revealed that the sequencing quality was good. The annotated data indicated that intronic and intergenic areas held the majority of SNPs and indels. Four subgroups of 121 non-heading Chinese cabbages were identified using principal component analysis, phylogenetic tree, and genetic structure analysis. An examination of genetic diversity revealed that while selfing may happen in subgroups C and D, heterozygosity may exist in subgroups A and B. In subgroup B, self-fertilization is not possible. There was a moderate degree of genetic differentiation between subgroups B and C (Fst = 0.0744347). For genes in certain sweep regions, we also ran GO enrich-ment and KEGG enrichment analysis. Two disease resistance-related genes, BraA01g042910.3.5C and BraA06g019360.3.5C, were examined. These findings will serve as a theoretical foundation for developing novel, clubroot disease-resistant types of non-heading Chinese cabbages.
[学术文献 ] Effects of Low Nighttime Temperature on Fatty Acid Content in Developing Seeds from Brassica napus L. Based on RNA-Seq and Metabolome 进入全文
Plants
Brassica napus L. is a vital plant oil resource worldwide. The fatty acid biosynthesis and oil accumulation in its seeds are controlled by several genetic and environmental factors, including daytime and nighttime temperatures. We analyzed changes in oleic and erucic acid content in two double haploid (DH) lines, DH0729, a weakly temperature-sensitive line, and DH0815, a strongly temperature-sensitive line, derived from B. napus plants grown at different altitudes (1600, 1800, 2000, 2200, and 2400 m a.s.l., 28.85° N, 112.35° E) and nighttime temperatures (20/18, 20/16, 20/13 and 20/10 °C, daytime/nighttime temperature). Based on medium- and long-chain fatty acid metabolites, the total oleic acid content 35 and 43 days after flowering was significantly lower in low nighttime temperature (LNT, 20/13 °C) plants than in high nighttime temperature (HNT, 20/18 °C) plants (HNT: 58-62%; LNT: 49–54%; an average decrease of 9%), and the total erucic acid content was significantly lower in HNT than in LNT plants (HNT: 1-2%; LNT: 8-13%; an average increase of 10%). An RNA-seq analysis showed that the expression levels of SAD (LOC106366808), ECR (LOC106396280), KCS (LOC106419344), KAR (LOC106367337), HB1(LOC106430193), and DOF5 (LOC111211868) in STSL seeds increased under LNT conditions. In STSL seeds, a base mutation in the cis-acting element involved in low-temperature responsiveness (LTR), the HB1 and KCS promoter caused loss of sensitivity to low temperatures, whereas that of the KCS promoter caused increased sensitivity to low temperatures.
[学术文献 ] BcAMT1;5 Mediates Nitrogen Uptake and Assimilation in Flowering Chinese Cabbage and Improves Plant Growth When Overexpressed in Arabidopsis 进入全文
Horticulturae
Nitrogen (N) is a major limiting factor for plant growth and vegetable production. Understanding the regulatory mechanisms of N uptake, transport, and assimilation is key to improving N use efficiency in plants. Ammonium transporters (AMTs) play an important role in plant N metabolism. In this study, we isolated an important AMT1 subfamily member (BcAMT1;5) with a highly conserved signatural AMT1 subfamily motif from flowering Chinese cabbage. Based on functional complementation in yeast mutant 31019b and overexpression of BcAMT1;5 in Arabidopsis, BcAMT1;5 is a functional AMT. Tissue expression analysis showed that BcAMT1;5 was mainly ex-pressed in roots and showed multiple N regime transcript patterns to respond to varying nutritional conditions. This was up-regulated by N-deficiency and down-regulated by supplying NH4+. The glucuronidase (GUS) activities of BcAMT1;5pro::GUS showed a similar change in response to different N conditions. Overexpression of BcAMT1;5 accelerated the growth of transgenic seedlings, increased NH4+ net influxes, and enhanced the content and accumulation of NH4+ and NO3− at low N concentrations. Additionally, it increased the transcript levels of N assimilation-related genes in shoots. These results indicate that BcAMT1;5 may participate in N uptake and assimilation under various N conditions in flowering Chinese cabbage, but it was differed obviously from other AMT1s.
