Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
Central Analytical Facilities, Mass Spectrometry Unit, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
Sci Rep. 2024 Nov 18;14(1):28490. doi: 10.1038/s41598-024-79402-2.
Citrus tristeza virus (CTV) causes economically important stem pitting in sensitive citrus types however the exact mechanisms of stem pitting development in citrus remain unclear. In this study, CTV infectious clones were used to study stem pitting induction in 'Duncan' grapefruit and 'Mexican' lime. A panel of open reading frame (ORF) replacement clones was generated focusing on the CTV ORFs implicated in stem pitting development and pathogenicity, namely p33, p18, p13 and p23. ORF replacements from severe- and mild-pitting CTV isolates were introduced into a mild-pitting infectious clone (genotype T36) to determine if stem pitting could be induced. A broad range of stem pitting outcomes were observed with ORF p18 (from isolate T3-KB) and ORF p23 (from isolate GFMS12-1.3) associated with enhanced stem pitting development. Metabolomic trends underlying the different stem pitting outcomes were further assessed by untargeted metabolite profiling. In each citrus host, the metabolite profiling identified statistically significant compounds that differed between stem pitting groups. These compounds were mainly phenolic acids and phenolic glycosides and are known to function as antioxidant and stress-signaling molecules. These metabolites can serve as targets for future time-course observations to potentially use mass spectrometry profiling to inform CTV management practices.
甜橙衰退病毒（CTV）可引起敏感柑橘品种的重要经济衰退，然而柑橘衰退茎陷斑病的发病机制仍不清楚。本研究使用 CTV 感染性克隆来研究‘邓肯’葡萄柚和‘墨西哥’莱檬的茎陷斑病诱导。一组开放阅读框（ORF）替换克隆被生成，重点关注与茎陷斑病发病机制和致病性相关的 CTV ORFs，即 p33、p18、p13 和 p23。从严重和轻度衰退的 CTV 分离物中引入 ORF 替换，以确定是否可以诱导茎陷斑病。用来自严重衰退的 CTV 分离物 T3-KB 的 p18ORF 和来自 GFMS12-1.3 分离物的 p23ORF 替换了轻度衰退的感染性克隆（基因型 T36），观察到广泛的茎陷斑病表型。代谢组学趋势进一步通过非靶向代谢物分析来评估不同茎陷斑病表型的基础。在每种柑橘寄主中，代谢组学分析鉴定了在茎陷斑病组之间存在统计学差异的化合物。这些化合物主要是酚酸和酚糖苷，已知其作为抗氧化和应激信号分子发挥作用。这些代谢物可以作为未来的时间过程观察的目标，有可能使用质谱分析来为 CTV 管理实践提供信息。
