感染CTV甜橙中挥发性成分的分析及萜类合成相关基因的表达变化

Analysis of Changes in Volatile Compounds by SPME-GC-MS Technique and Expression of Terpenoid Biosynthesis-Related Genes in Citrus sinensis Plants Infected with CTV

为明确柑橘衰退病毒(Citrus tristeza virus,CTV)对柑橘挥发性物质的影响,本研究采用顶空固相微萃取法(Headspace Solid-phase Micro-Extractions,HS-SPEM)结合气相色谱-质谱联用(Gas Chromatography-Mass Spectrometry,GC-MS)技术分析了感染CTV的甜橙和健康甜橙挥发性成分.结果表明,CTV侵染使甜橙挥发性成分总量显著降低,仅为健康甜橙的71.00%,与健康甜橙中检测出的59种挥发性成分相比,感病甜橙中检测出55种,两者共有物质51种,其中33种的质量分数显著降低;此外,还有8种仅在健康甜橙中被检出,4种仅在CTV侵染甜橙中被特异检出,分别为百里香酚、香叶酸甲酯、石竹素和2-亚甲基-莰烷;检出的挥发性物质以萜类居多,为44种.采用实时荧光定量PCR(RT-qPCR)技术进一步分析了4个萜类合成关键基因(香叶基香叶基二磷酸合酶、法呢基焦磷酸合酶、γ-萜品烯合酶和柠檬烯合酶)表达量,结果表明,感染CTV甜橙中4个基因表达显著下降,与感染CTV甜橙中γ-萜品烯和柠檬烯质量分数显著减少趋势一致,暗示了CTV侵染甜橙影响了寄主萜类合成途径进而影响了挥发性物质的释放.

To clarify the effect of Citrus tristeza virus(CTV)on citrus volatile compounds,the technology of Headspace Solid-phase Micro-extractions(HS-SPEM)coupled with Gas Chromatography-Mass Spectrometry(GC-MS)was used to analyze the volatile components of CTV-infected and healthy sweet orange plants in this study.The results showed that CTV significantly reduced the content of total volatile components of sweet orange,which was only 71.00%of the healthy ones.Fifty-nine volatile components were identified in healthy sweet orange plants,while 55 volatile components were detected in sweet orange plants infected with CTV isolate CT14.There were 51 common volatile components among them,of which,the contents of 33 components reduced significantly in sweet orange infected with CTV.Besides,eight volatile substances were detected only in healthy plants,and four volatile components were detected only in sweet orange infected with CT14,including thymol,methyl geranate,caryophyllene oxide and 2-methylenebornaney.Among all these volatile substances,the most components was the terpenoids,in total 44.The expression of 4 genes(GGPPS,FPPS,TPIS,and LMS)involving in terpenoids biosynthetic pathways was analyzed by reverse-transcription quantitative polymerase chain reaction(RT-qPCR).The results showed that the expression levels of 4 genes were all down-regulated significantly in sweet orange plants infected with CTV,which was consistent with the result that the emission ofγ-Terpinene and limonene was decreased in CTV-infected plants.The results indicated that CTV infection affected the biosynthesis of terpenoids and the release of volatile compounds in sweet orange plants.