Green Kimberly A, Berry Daniel, Feussner Kirstin, Eaton Carla J, Ram Arvina, Mesarich Carl H, Solomon Peter, Feussner Ivo, Scott Barry
School of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.
Bioprotection Research Centre, Massey University, Palmerston North, 4442, New Zealand.
New Phytol. 2020 Jul;227(2):559-571. doi: 10.1111/nph.16528. Epub 2020 Apr 13.
Epichloë festucae is an endophytic fungus that forms a symbiotic association with Lolium perenne. Here we analysed how the metabolome of the ryegrass apoplast changed upon infection of this host with sexual and asexual isolates of E. festucae. A metabolite fingerprinting approach was used to analyse the metabolite composition of apoplastic wash fluid from uninfected and infected L. perenne. Metabolites enriched or depleted in one or both of these treatments were identified using a set of interactive tools. A genetic approach in combination with tandem MS was used to identify a novel product of a secondary metabolite gene cluster. Metabolites likely to be present in the apoplast were identified using MarVis in combination with the BioCyc and KEGG databases, and an in-house Epichloë metabolite database. We were able to identify the known endophyte-specific metabolites, peramine and epichloëcyclins, as well as a large number of unknown markers. To determine whether these methods can be applied to the identification of novel Epichloë-derived metabolites, we deleted a gene encoding a NRPS (lgsA) that is highly expressed in planta. Comparative MS analysis of apoplastic wash fluid from wild-type- vs mutant-infected plants identified a novel Leu/Ile glycoside metabolite present in the former.
禾本科内生真菌（Epichloë festucae）是一种与多年生黑麦草（Lolium perenne）形成共生关系的内生真菌。在此，我们分析了在用禾本科内生真菌的有性和无性分离株感染该宿主后，黑麦草质外体的代谢组如何变化。采用代谢物指纹图谱方法分析未感染和感染多年生黑麦草的质外体洗液的代谢物组成。使用一组交互式工具鉴定在这两种处理中的一种或两种中富集或减少的代谢物。结合串联质谱的遗传学方法用于鉴定次生代谢物基因簇的一种新产物。使用MarVis结合BioCyc和KEGG数据库以及一个内部的禾本科内生真菌代谢物数据库，鉴定可能存在于质外体中的代谢物。我们能够鉴定出已知的内生真菌特异性代谢物、麦角酰胺和禾本科内生真菌环肽，以及大量未知标记物。为了确定这些方法是否可用于鉴定新的禾本科内生真菌衍生代谢物，我们删除了一个在植物中高表达的编码非核糖体肽合成酶（lgsA）的基因。对野生型感染植物与突变体感染植物的质外体洗液进行比较质谱分析，鉴定出前者中存在一种新的亮氨酸/异亮氨酸糖苷代谢物。
