[前沿资讯] Wheat growth, applied water use efficiency and flag leaf metabolome under continuous and pulsed deficit irrigation 进入全文
[学术文献] sRNA Profiling Combined With Gene Function Analysis Reveals a Lack of Evidence for Cross-Kingdom RNAi in the Wheat – Zymoseptoria tritici Pathosystem 进入全文
Cross-kingdom small RNA (sRNA) silencing has recently emerged as a mechanism facilitating fungal colonization and disease development. Here we characterized RNAi pathways in Zymoseptoria tritici, a major fungal pathogen of wheat, and assessed their contribution to pathogenesis. Computational analysis of fungal sRNA and host mRNA sequencing datasets was used to define the global sRNA populations in Z. tritici and predict their mRNA targets in wheat. 389 in planta-induced sRNA loci were identified. sRNAs generated from some of these loci were predicted to target wheat mRNAs including those potentially involved in pathogen defense. However, molecular approaches failed to validate targeting of selected wheat mRNAs by fungal sRNAs. Mutant strains of Z. tritici carrying deletions of genes encoding key components of RNAi such as Dicer-like (DCL) and Argonaute (AGO) proteins were generated, and virulence bioassays suggested that these are dispensable for full infection of wheat. Nonetheless, our results did suggest the existence of non-canonical DCL-independent pathway(s) for sRNA biogenesis in Z. tritici. dsRNA targeting essential fungal genes applied in vitro or generated from an RNA virus vector in planta in a procedure known as HIGS (Host-Induced Gene Silencing) was ineffective in preventing Z. tritici growth or disease. We also demonstrated that Z. tritici is incapable of dsRNA uptake. Collectively, our data suggest that RNAi approaches for gene function analyses in this fungal species and potentially also as a control measure may not be as effective as has been demonstrated for some other plant pathogenic fungi.
[学术文献] Developing New Oligo Probes to Distinguish Specific Chromosomal Segments and the A, B, D Genomes of Wheat (Triticum aestivum L.) Using ND-FISH 进入全文
Non-denaturing FISH (ND-FISH) technology has been widely used to study the chromosomes of Triticeae species because of its convenience. The oligo probes for ND-FISH analysis of wheat (Triticum aestivum L.) chromosomes are still limited. In this study, the whole genome shotgun assembly sequences (IWGSC WGA v0.4) and the first version of the reference sequences (IWGSC RefSeq v1.0) of Chinese Spring (T. aestivum L.) were used to find new tandem repeats. One hundred and twenty oligo probes were designed according to the new tandem repeats and used for ND-FISH analysis of chromosomes of wheat Chinese Spring. Twenty nine of the 120 oligo probes produce clear or strong signals on wheat chromosomes. Two of the 29 oligo probes can be used to conveniently distinguish wheat A-, B-, and D-genome chromosomes. Sixteen of the 29 oligo probes only produce clear or strong signals on the subtelomeric regions of 1AS, 5AS, 7AL, 4BS, 5BS, and 3DS arms, on the telomeric regions of 1AL, 5AL, 2BS, 3BL, 6DS, and 7DL arms, on the intercalary regions of 4AL and 2DL arms, and on the pericentromeric regions of 3DL and 6DS arms. Eleven of the 29 oligo probes generate distinct signal bands on several chromosomes and they are different from those previously reported. In addition, the short and long arms of 6D chromosome have been confirmed. The new oligo probes developed in this study are useful and convenient for distinguishing wheat chromosomes or specific segments of wheat chromosomes.
[学术文献] Influence of different nitrogen application on flour properties, gluten properties by HPLC and end-use quality of Korean wheat 进入全文
This study was performed to identify how the different levels of nitrogen application affected the variances of gluten properties and end-use qualities and the differences of variances among Korean wheat cultivars. Protein and dry gluten content, SDS sedimentation volume and water absorption of Mixolab increased as nitrogen application increased. This ratio of the increase was higher in Korean wheat cultivars for bread than in Korean wheat cultivars for noodles and cookies. The proportion of (α+β)-gliadin measured by reversed-phase high-performance liquid chromatography (RP-HPLC) increased, but the proportion of ω- and γ-gliadin decreased as the protein content increased. The Korean wheat cultivars for bread showed a high proportion of (α+β)-gliadin increase, the Korean cultivars for noodles had a high proportion of γ-gliadin decrease and the Korean wheat cultivars for cookies had a high proportion of ω-gliadin decrease. However, there was no variation of the component in the proportion of glutenin component measured by RP-HPLC, even though the protein content was increased, but all of the protein fractions measured by size exclusion (SE)-HPLC were increased. The soluble monomeric protein showed a high proportion of Korean wheat cultivars for bread by the increase of protein content. Bread loaf volume increased by the increase of protein content but there were no variances in the ratio of increase among Korean wheat cultivars. The cookie diameter decreased with the increase of protein content, and this ratio of decrease was the highest in Korean wheat cultivars for cookies. The hardness of cooked noodles also increased by the increase of protein content but there were no variations in springiness and cohesiveness. The decrease proportion of ω-gliadin affected the increase of bread loaf volume, the hardness of cooked noodles, and the decrease of cookie diameter.
[前沿资讯] Infection by cyst nematodes induces rapid remodelling of developing xylem vessels in wheat roots 进入全文
胞囊线虫诱导寄主植物根细胞形成合胞体，并以此为食。对这些取食部位进行全面的组织学研究，由于其形状的变化和在根组织深处的位置而变得复杂。利用组织清除和共聚焦显微镜，我们检测了受胞囊线虫(Heterodera avenae)感染的小麦根厚切片(高达150μm)。该方法可以清晰地观察到线虫的取食部位和周围组织，分辨率足以揭示线虫、合胞体和宿主维管组织在细胞水平上的空间关系。合胞体附近的元胞管区域被发现偏离了典型的发育模式。这些区域的木质部导管元素没有伸长，而是发生放射状扩张，变得短而丰满，而不是长而圆润。进一步的调查显示，血管元素在感染后不久就停止伸长，之后它们的外细胞壁的次生增厚(木质化)发生延迟，其中一些元素最终被合并到合胞体的喂养位点。通过干扰，正常情况下会导致程序性细胞死亡的发育，H. avenae可以使木质部导管元素存活下来，以便以后被寄生虫利用。