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- Author or Editor: Yu Xu x
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Wheat Fusarium head blight (FHB) may cause serious losses in grain yield and quality in China. More than 7 million hectares which approximately accounts for 25% of the total areas in China is infected by the disease. The cultivation of wheat varieties with resistance to Fusarium head blight is recognized as one of the most important components to diminish losses due to this disease. Chinese wheat breeders have commenced the research on FHB since 1950s. Wheat cultivars with improved FHB resistance were developed through conventional breeding. Some famous resistant varieties such as Sumai 3, Yangmai 158 and Ning 7840 were released from Jiangsu Academy of Agricultural Sciences, these varieties were widely applied in wheat production and breeding programs. Significant achievements concerning molecular mapping and marker assisted selection have been made in the past decade. The major QTL on chromosome 3BS was identified and located in the same region on chromosome 3BS in Sumai 3, Ning 894037, Wangshuibai, and Chinese Spring. Using SSR marker in this QTL region for assisted selection, some lines with the same resistance to FHB were obtained. New STS markers and SSCP markers were developed and will be tested for the efficiency of MAS. However, further achievements are still hindered by a number of constraints. More FHB resistance genetic resources from landrace in middle to lower reaches of Yangtze River are necessary to be used for improving FHB resistant. The genetic mechanism of the varieties contributing the resistance to improved cultivars is needed to be understood. Development of functional markers for FHB is discussed.
Objective of this study was to assess the quantification of osteocalcin (OCN) expression by ovine osteoblasts cultured with different concentrations of sodium fluoride (F) and sodium selenite (Se) to evaluate the interaction of these agents on OCN expression in vitro . We wanted to demonstrate a possible protective effect of selenium on the toxic effect of fluoride. Osteoblasts were isolated by complete trypsin and collagenase digestion from ovine calvarial bone and cultured in DMEM supplemented with 15% FBS at 37 °C in a humidified 5% CO 2 incubator. Identified osteoblasts were divided into one control group (C) and eight experimental groups, which were exposed to different concentrations of sodium fluoride (F; 0, 0.5, 1 mM) sodium selenite (Se; 0, 0.1, 1 μM). At different time points after treatment total RNA was extracted and reverse transcribed into first-strand cDNA. OCN mRNA was indirectly measured by real-time fluorescent quantitative PCR (qPCR). OCN mRNA expression in F 1 mM with Se 1 μM group was found to have a high peak at day seven and was lower before and afterwards. Expression of OCN mRNA in all groups except control could be promoted by F and/or Se showing a general upregulation. Furthermore, the toxicity from excessive exposure of osteoblast with F could be circumvented by usage of moderate concentration of Se. Osteoblasts cultured in vitro may have stressful responses to F and Se at the first few days. Low concentrations of Se inhibit the toxic effects of high concentrations of F. Therefore, F and Se could be used as antagonistic factors, which could regulate osteocalcin expression.
Changes in microbial population, pH, sugar, organic acid, anthocyanins, total soluble phenolics, and anti-glucosidase contents were measured during fermentation of mulberry juice at 30 °C by probiotic Leuconostoc mesenteroides showing rapid growth after an approximately 1-day lag phase and reaching a maximum of 8.6 log CFU ml−1 after 4 d. During the rapid growth phase, the main mulberry juice sugars, glucose and fructose, were largely consumed, and the acidic metabolites, lactic acid and acetic acid, were produced accordingly. A slow decrease in the concentration of the main organic acid, citric acid, was also observed during fermentation. After 4 d fermentation, anthocyanin content showed a 44.4% reduction, but the total amount of soluble phenolics and α-glucosidase inhibitory activity showed no significant changes (P>0.05). This suggests that L. mesenteroides fermentation of mulberry juice is a good strategy to enhance its probiotic value and to decrease the sugar content without changing the anti-glucosidase activity, which is required to reduce postprandial rise in blood glucose.
Fusarium head blight (FHB), mainly caused by Fusarium graminearum , is a very serious disease in wheat and barley production area. FHB epidemics cause yield decreases and production of mycotoxin that renders the grain useless for flour and malt products. Understanding the infection mechanism of F. graminearum plays an important role for the disease control. In present study, green fluorescence protein (GFP)-tagged were infected to wheat and barley varieties by single floret injection and screened via GFP signal. Results showed similar infection pattern of F. graminearum on both wheat and barley. Pathogen geminated in the inoculated spikelets, grew on the top of ovary or between lemma and palea, and extended towards and through rachis to the adjacent spikelets to infect the whole spike. When a spike of cultivar with FHB resistance was inoculated by F. graminearum , only the injected spikelet showed symptom at 6 days past inoculation (dpi). GFP signals indicated that F. graminearum colonized only in the inoculated spikelet and stop at the compact tissue of rachilla at 6 dpi. On the contrary, the diseased spikelets were up to 5 at 6 dpi in the spike of cultivars susceptible to FHB. F. graminearum extended through compact tissue to rachis and infected to the adjacent spikelets by spreading upward and downward to adjacent florets inter- and intra-cellularly in vascular bundles and cortical tissue of the rachis.
Chinese endemic wheat landraces possess unique morphological features and desirable traits, useful for wheat breeding. It is important to clarify the relationship among these landraces. In this study, 21 accessions of the four Chinese endemic wheat landrace species were investigated using single-copy genes encoding plastid Acetyl-CoA carboxylase (Acc-1) and 3-phosphoglycerate kinase (Pgk-1) in order to estimate their phylogenetic relationship. Phylogenetic trees were constructed using maximum parsimony (MP), maximum likelihood (ML) and Bayesian, and TCS network and gene flow values. The A and B genome sequences from the Pgk-1 loci indicated that three accessions of Triticum petropavlovskyi were clustered into the same subclade, and the T. aestivum ssp. tibetanum and the Sichuan white wheat accessions were grouped into a separate subclade. Based on the Acc-1 gene, T. aestivum ssp. tibetanum and T. aestivum ssp. yunnanense were grouped into one subclade in the A genome; the B genome from T. petropavlovskyi and T. aestivum ssp. tibetanum, and the Sichuan white wheat complex and T. aestivum ssp. tibetanum were grouped in the same clades. The D genome of T. aestivum ssp. yunnanense clustered with T. petropavlovskyi. Our findings suggested that (1) T. petropavlovskyi is distantly related to the Sichuan white wheat complex; (2) T. petropavlovskyi, T. aestivum ssp. tibetanum and T. aestivum ssp. yunnanense are closely related; (3) T. aestivum ssp. tibetanum is closely related to T. aestivum ssp. yunnanense and the Sichuan white wheat complex; and (4) T. aestivum ssp. tibetanum may be an ancestor of Chinese endemic wheat landraces.
