Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, NSW, 2006, Australia.
Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, NSW, 2006, Australia.
Phytochemistry. 2019 May;161:139-148. doi: 10.1016/j.phytochem.2019.02.007. Epub 2019 Mar 2.
Rust fungi, which are responsible for some of the world's most destructive plant diseases, are named for the distinctive rusty colour of one or more of their spore forms. Rust spore pigments are thought to provide protection against UV radiation and oxidative stress, and may act as virulence factors. However, with the exception of daisy rust spores, the identity and relative abundance of the carotenoids in the rust spore cytoplasm have not been investigated using modern analytical methods, and little is known about the dependence of the carotenoid complement on species, pathotype, spore-colour mutations and season. We developed and validated a method to separate, identify and quantify rust carotenoids by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with mass spectrometry. The carotenoids identified were lycopene, γ-carotene, β-carotene and phytoene. Rates of carotenoid degradation depended greatly on spore storage conditions, with freezing at -80 °C providing optimal stability. Carotenoid profiles of 103 isolates from 14 rust species were compared, showing that the ratio γ-carotene:β-carotene varied substantially among species. Total carotenoid content was generally lower in spring than in autumn (Sydney, Australia)-possibly due to differences in solar exposure-but the percentage of individual carotenoids was relatively stable. Among the colour mutants tested, chocolate mutants of Puccinia graminis f. sp. tritici (wheat stem rust) contained no carotenoid pigments, while albino mutants of P. striiformis f. sp. tritici (wheat stripe rust) contained only phytoene, a colourless carotenoid. We discuss our results in terms of the biogenesis and biological functions of carotenoids in rust fungi.
锈菌会引起一些世界上最具破坏性的植物病害，其名称来源于其一种或多种孢子形式的独特锈色。锈菌孢子色素被认为可以提供对紫外线辐射和氧化应激的保护，并且可能作为毒力因子发挥作用。然而，除了雏菊锈菌孢子之外，锈菌孢子细胞质中的类胡萝卜素的身份和相对丰度尚未使用现代分析方法进行研究，并且对类胡萝卜素补充物对物种、致病型、孢子颜色突变和季节的依赖性知之甚少。我们开发并验证了一种通过反相高效液相色谱（RP-HPLC）结合质谱分离、鉴定和定量锈菌类胡萝卜素的方法。鉴定出的类胡萝卜素为番茄红素、γ-胡萝卜素、β-胡萝卜素和phytoene。类胡萝卜素的降解速度很大程度上取决于孢子的储存条件，在-80°C 下冷冻可提供最佳稳定性。比较了来自 14 种锈菌的 103 个分离物的类胡萝卜素图谱，表明γ-胡萝卜素：β-胡萝卜素的比值在物种之间有很大差异。春季节总类胡萝卜素含量通常低于秋季（澳大利亚悉尼）-可能是由于太阳暴露的差异-但个别类胡萝卜素的百分比相对稳定。在所测试的颜色突变体中，小麦条锈菌 Puccinia striiformis f. sp. tritici 的巧克力突变体不含类胡萝卜素色素，而小麦秆锈菌 Puccinia graminis f. sp. tritici 的白化突变体仅含有phytoene，一种无色的类胡萝卜素。我们根据锈菌中类胡萝卜素的生物发生和生物学功能讨论了我们的结果。
