The Eucalyptus grandis NBS-LRR Gene Family: Physical Clustering and Expression Hotspots.
The Eucalyptus grandis NBS-LRR Gene Family: Physical Clustering and Expression Hotspots.
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DOI：
10.3389/fpls.2015.01238
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发表时间：
2015
影响因子：
5.6
通讯作者：
Külheim C
中科院分区：
文献类型：
--
作者：
Christie N;Tobias PA;Naidoo S;Külheim C
大桉树是一种商业上重要的硬木树种，已知易受许多害虫和病原体的影响。因此，确定防御机制是研究的重点。已发表的大肠杆菌基因组有助于鉴定一类包含核苷酸结合位点和富含亮氨酸重复结构域（NBS-LRR）的重要抗性基因。使用迭代搜索过程，我们确定了大叶蝉基因组内的NBS-LRR基因模型。我们描述了基因模型并确定了它们的基因组排列。在受到真菌病原菌（Chrysoporthe austrstroafricana）和害虫（Leptocybe invasa）侵染后，研究了该基因的表达模式。基于NB-ARC结构域，共确定了1515个NBS-LRR推定编码序列，并将其划分为Toll或白细胞介素-1受体（TIR）和螺旋状（CC）两大类。NBS-LRR基因丰富的区域被鉴定为76%组织在三个或更多基因的集群中。另外还鉴定出272个假定的不完全耐药基因。结果表明，与其他木本植物相比，大叶青的TIR与CC分类基因的比例更高，而单NBS-LRR基因的比例更低。转录组谱显示了物理簇内的表达热点，包括许多不完整基因的表达。NBS-LRR基因的聚类与抗性和易感植物的差异表达反应相关，表明该基因家族的物理排列具有功能相关性。本研究分析了大叶豆NBS-LRR基因库和表达，为鉴定新的和功能性的r基因提供了重要的资源；加强复原力战略的关键目标。
Eucalyptus grandis is a commercially important hardwood species and is known to be susceptible to a number of pests and pathogens. Determining mechanisms of defense is therefore a research priority. The published genome for E. grandis has aided the identification of one important class of resistance (R) genes that incorporate nucleotide binding sites and leucine-rich repeat domains (NBS-LRR). Using an iterative search process we identified NBS-LRR gene models within the E. grandis genome. We characterized the gene models and identified their genomic arrangement. The gene expression patterns were examined in E. grandis clones, challenged with a fungal pathogen (Chrysoporthe austroafricana) and insect pest (Leptocybe invasa). One thousand two hundred and fifteen putative NBS-LRR coding sequences were located which aligned into two large classes, Toll or interleukin-1 receptor (TIR) and coiled-coil (CC) based on NB-ARC domains. NBS-LRR gene-rich regions were identified with 76% organized in clusters of three or more genes. A further 272 putative incomplete resistance genes were also identified. We determined that E. grandis has a higher ratio of TIR to CC classed genes compared to other woody plant species as well as a smaller percentage of single NBS-LRR genes. Transcriptome profiles indicated expression hotspots, within physical clusters, including expression of many incomplete genes. The clustering of putative NBS-LRR genes correlates with differential expression responses in resistant and susceptible plants indicating functional relevance for the physical arrangement of this gene family. This analysis of the repertoire and expression of E. grandis putative NBS-LRR genes provides an important resource for the identification of novel and functional R-genes; a key objective for strategies to enhance resilience.