Fatty acid composition and lipid profiles as chemotaxonomic markers of phytopathogenic fungi Puccinia malvacearum and P. glechomatis

Abstract

The analysis of the overall fatty acid pattern as well as their distribution in various lipid classes of phytopathogenic fungi Puccinia malvacearum and P. glechomatis are considered as chemotaxonomic biomarkers. Puccinia malvacearum on Alcea rosea and P. glechomatis on Glechoma hederacea collected from plants grown in various localities were analysed to determine their fatty acid composition. Both species synthesised significant amounts of saturated palmitic and stearic acids as well as 9,10-epoxy-octadecanoic acid, which rarely occurs in the nature. Both species synthesised hydroxy FAs including 9,10-dihydroxy octadecanoic acid and long-chain 2-hydroxy fatty acids.2-hydroxy 18:0 and 3-hydroxy 20:0 fatty acids were present only in P. malvacearum spores, and these may be the chemotaxonomic markers of the species. Ultra-high performance liquid chromatography mass spectrometry was performed for a comparative lipidomic analysis of P. malvacearum and P. glechomatis. The results revealed the complexity of molecular lipid species of these fungi. P. malvacearum and P. glechomatis lipids were characterised by the presence of a high number of triglyceride (TG) species. 9,10-epoxy octadecanoic fatty acid was found in TGs. Among the many types of oxidised TGs identified in P. glechomatis lipids, the most abundant species corresponds to TG(22:5+6O_17:0_18:2). P. malvacearum and P. glechomatis produced various ceramide species with different FAs from 14 to 24 chain-length. Unusual lipids like (O-acyl)-ω-hydroxy FA 18:0/18:0 in P. glechomatis and (O-acyl)-ω-hydroxy FA 18:0/20:0 and 18:0/22:0 in P. malvacearum were detected. The analysis of the polar lipid composition showed the presence of phosphatidylcholine and phosphatidylethanolamine as the main phospholipid classes of Puccinia spp. with the highest diversity of molecular species. Other phospholipids phosphatidic acid, phosphatidylglycerol phosphatidylserine and phosphatidylinositol were present in smaller amounts. The diversity of the neutral and polar lipid composition and fatty acid profile of P. malvacearum and P. glechomatis can be used in chemotaxonomic studies.

Keywords: Epoxy-octadecanoic fatty acid; Lipidomic analysis; Puccinia glechomatis; Puccinia malvacearum; Rust fungi.