Department of Plant Agriculture, University of Guelph, 4890 Victoria Ave. N., P.O. Box 7000, Vineland Station, ON, L0R 2E0, Canada.
Plant Cell Rep. 2011 Oct;30(10):1799-809. doi: 10.1007/s00299-011-1087-x. Epub 2011 May 19.
Ginger (Zingiber officinale Roscoe), is an important spice crop that is badly affected by Ralstonia solanacearum wilt. Ginger does not set seed and sexual recombination has never been reported. In spite of extensive search in its habitats, no resistance source to Ralstonia induced bacterial wilt, could be located in ginger. Curcuma amada Roxb. is a potential donor for bacterial wilt resistance to Z. officinale, if the exact mechanism of resistance is understood. Pathogenesis-related (PR)-5 proteins are a family of proteins that are induced by different phytopathogens in many plants and share significant sequence similarity with thaumatin. Two putative PR5 genes, CaPR5 and ZoPR5, were amplified from C. amada and ginger, which encode precursor proteins of 227 and 224 amino acid residues, respectively, and share high homology with a number of other PR5 genes. The secondary and three-dimensional structure comparison did not reveal any striking differences between these two proteins. The expression of Ca and ZoPR5s under R. solanacearum inoculation was analyzed at different time points using quantitative real-time PCR (qRT-PCR). Our results reveal that CaPR5 is readily induced by the bacterium in C. amada, while ZoPR5 induction was very weak and slow in ginger. These results suggest that the CaPR5 could play a role in the molecular defense response of C. amada to pathogen attack. This is the first report of the isolation of PR5 gene from the C. amada and Z. officinale. Promoter analysis indicates the presence of a silencing element binding factor in ZoPR5-promoter, but not in CaPR5. Prospective promoter elements, such as GT-1 box and TGTCA, implicated as being positive regulatory elements for expression of PR proteins, occur in the 5'-flanking sequences of the CaPR5. Transient GUS expression study confirms its action with a weaker GUS expression in ginger, indicating that the PR5 expression may be controlled in the promoter.
生姜（Zingiber officinale Roscoe）是一种重要的香料作物，但其易受青枯病菌（Ralstonia solanacearum）引起的枯萎病的影响。生姜不会结籽，也从未有过性重组的报道。尽管在其栖息地进行了广泛的搜索，但仍未找到对青枯病有抗性的生姜来源。如果了解了确切的抗性机制，Curcuma amada Roxb. 可能是 Z. officinale 细菌性枯萎病抗性的潜在供体。
病程相关（PR）-5 蛋白是一类在许多植物中被不同植物病原体诱导的蛋白，它们与 thaumatin 具有显著的序列相似性。从 C. amada 和生姜中扩增出两个假定的 PR5 基因，CaPR5 和 ZoPR5，分别编码 227 和 224 个氨基酸残基的前体蛋白，与许多其他 PR5 基因具有高度同源性。二级和三维结构比较没有显示这两种蛋白质之间有任何显著的差异。使用定量实时 PCR（qRT-PCR）在不同时间点分析 Ca 和 ZoPR5s 在 R. solanacearum 接种下的表达。我们的结果表明，CaPR5 很容易被细菌诱导在 C. amada 中，而 ZoPR5 在生姜中的诱导非常弱且缓慢。这些结果表明，CaPR5 可能在 C. amada 对病原体攻击的分子防御反应中发挥作用。这是首次从 C. amada 和 Z. officinale 中分离 PR5 基因的报道。启动子分析表明，ZoPR5 启动子中存在一个沉默元件结合因子，但在 CaPR5 中不存在。GT-1 盒和 TGTCA 等潜在启动子元件被认为是 PR 蛋白表达的正调控元件，出现在 CaPR5 的 5' 侧翼序列中。瞬时 GUS 表达研究证实了其作用，在生姜中的 GUS 表达较弱，表明 PR5 的表达可能在启动子中受到调控。
