Clubroot is one of the major diseases adversely affecting Chinese cabbage (Brassica rapa) yield and quality. To precisely characterize the Plasmodiophora brassicae infection on Chinese cabbage, we developed a dual fluorescent staining method for simultaneously examining the pathogen, cell structures, and starch grains. The number of starch (amylopectin) grains increased in B. rapa roots infected by P. brassicae, especially from 14 to 21 days after inoculation. Therefore, the expression levels of 38 core starch metabolism genes were investigated by quantitative real-time PCR. Most genes related to starch synthesis were up-regulated at seven days after the P. brassicae inoculation, whereas the expression levels of the starch degradation-related genes increased at 14 days after the inoculation. Then genes encoding the core enzymes involved in starch metabolism were investigated by assessing their chromosomal distributions, structures, duplication events, and synteny among Brassica species. Genome comparisons indicated that 38 non-redundant genes belonging to six core gene families related to starch metabolism are highly conserved among Arabidopsis thaliana, B. rapa, Brassica nigra, and Brassica oleracea. Genome sequencing projects have revealed that P. brassicae obtained host nutrients by manipulating plant metabolism. Starch may serve as a carbon source for P. brassicae colonization as indicated by the histological observation and transcriptomic analysis. Results of this study may elucidate the evolution and expression of core starch metabolism genes and provide researchers with novel insights into the pathogenesis of clubroot in B. rapa.

中文翻译：

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甘蓝根霉感染协同诱导大白菜淀粉含量变化及代谢相关基因调控


根肿病是影响大白菜产量和品质的主要病害之一。为了精确表征大白菜上的芸苔根霉感染，我们开发了一种双荧光染色方法，可同时检查病原体、细胞结构和淀粉粒。受芸苔白菜病感染的白菜根中淀粉（支链淀粉）粒的数量增加，特别是在接种后14至21天。因此，通过实时定量PCR研究了38个核心淀粉代谢基因的表达水平。大多数与淀粉合成相关的基因在接种甘蓝后7天时表达量上调，而淀粉降解相关基因的表达水平在接种后14天时增加。然后，通过评估芸苔属物种中编码参与淀粉代谢的核心酶的基因的染色体分布、结构、重复事件和同线性，对这些基因进行了研究。基因组比较表明，属于与淀粉代谢相关的6个核心基因家族的38个非冗余基因在拟南芥、白菜、黑芥和甘蓝中高度保守。基因组测序项目表明，甘蓝菜通过操纵植物代谢来获取宿主营养。组织学观察和转录组分析表明，淀粉可以作为芸苔假单胞菌定殖的碳源。这项研究的结果可能阐明核心淀粉代谢基因的进化和表达，并为研究人员提供白菜根肿病发病机制的新见解。