Bharathi Kosaraju, Santosh P, Sreenath H L
Plant Biotechnology Division, Unit of Central Coffee Research Institute, Coffee Board, Manasagangothri, Mysore, 570 006, India.
3 Biotech. 2017 May;7(1):45. doi: 10.1007/s13205-017-0715-8. Epub 2017 Apr 25.
Of the two commercially cultivated coffee (Coffea) species, C. arabica (arabica) is highly susceptible and C. canephora (robusta) is highly resistant to the insect pest Xylotrechus quadripes (Coleoptera: Cerambycidae), commonly known as coffee white stem borer (CWSB). We constructed a forward-subtracted cDNA library by Suppression Subtractive Hybridization (SSH) from robusta bark tissue for profiling genes induced by CWSB infestation. Among the 265 unigenes of the SSH EST library, 7 unigenes (5 contigs and 2 singletons) matching different pectin-degrading enzymes were discovered. These ESTs matched one pectate lyase, three polygalacturonases, and one pectin acetylesterase gene. Quantitative real-time PCR (qRT-PCR) revealed that CWSB infestation strongly induces the pectate lyase gene at 72 h. Complete cDNA sequence of the pectate lyase gene was obtained through 3' and 5' RACE reactions. It was a 1595 bp long sequence that included full CDS and both UTRs. Against C. canephora genome sequences in Coffee Genome Hub database ( http://coffee-genome.org/ ), it had 22 matches to different pectate lyase genes mapped on 9 of the 11 pseudochromosomes, the top match being Cc07_g00190 Pectate lyase. In NCBI database, it matched pectate lyase sequences of several plants. Apart from C. canephora, the closest pectate lyase matches were from Sesamum indicum and Nicotiana tabacum. The pectinolytic enzymes discovered here are thought to play a role in the production of oligogalacturonides (OGs) which act as Damage-Associated Molecular Pattern (DAMP) signals eliciting innate immunity in plants. The pectate lyase gene, induced by CWSB infestation, along with other endogenous pectinolytic enzymes and CWSB-specific elicitors, may be involved in triggering basal defense responses to protect the CWSB-damaged tissue against pathogens, as well as to contain CWSB in robusta.
在两种商业种植的咖啡（咖啡属）品种中，阿拉比卡咖啡（C. arabica）对害虫咖啡旋皮天牛（Xylotrechus quadripes，鞘翅目：天牛科）高度敏感，而卡内弗拉咖啡（C. canephora）对该害虫具有高度抗性，咖啡旋皮天牛俗称咖啡白茎天牛（CWSB）。我们通过抑制性消减杂交（SSH）从罗布斯塔树皮组织构建了一个正向消减cDNA文库，用于分析受CWSB侵染诱导的基因。在SSH EST文库的265个单基因中，发现了7个与不同果胶降解酶匹配的单基因（5个重叠群和2个单拷贝）。这些EST与一个果胶酸裂解酶、三个多聚半乳糖醛酸酶和一个果胶乙酰酯酶基因匹配。实时定量PCR（qRT-PCR）显示，CWSB侵染在72小时时强烈诱导果胶酸裂解酶基因。通过3'和5' RACE反应获得了果胶酸裂解酶基因的完整cDNA序列。它是一个1595 bp长的序列，包括完整的CDS和两个UTR。与咖啡基因组中心数据库（http://coffee-genome.org/）中的卡内弗拉咖啡基因组序列相比，它与映射在11条假染色体中的9条上的不同果胶酸裂解酶基因有22个匹配，最匹配的是Cc07_g00190果胶酸裂解酶。在NCBI数据库中，它与几种植物的果胶酸裂解酶序列匹配。除了卡内弗拉咖啡，最接近的果胶酸裂解酶匹配序列来自芝麻和烟草。这里发现的果胶分解酶被认为在低聚半乳糖醛酸（OGs）的产生中起作用，低聚半乳糖醛酸作为损伤相关分子模式（DAMP）信号引发植物的先天免疫。由CWSB侵染诱导的果胶酸裂解酶基因，连同其他内源性果胶分解酶和CWSB特异性激发子，可能参与触发基础防御反应，以保护受CWSB损伤的组织免受病原体侵害，并在罗布斯塔中控制CWSB。
