Phenalenone-type phytoalexins mediate resistance of banana plants ( Musa spp.) to the burrowing nematode Radopholus similis

Abstract

The global yield of bananas-one of the most important food crops-is severely hampered by parasites, such as nematodes, which cause yield losses up to 75%. Plant-nematode interactions of two banana cultivars differing in susceptibility to Radopholus similis were investigated by combining the conventional and spatially resolved analytical techniques 1 H NMR spectroscopy, matrixfree UV-laser desorption/ionization mass spectrometric imaging, and Raman microspectroscopy. This innovative combination of analytical techniques was applied to isolate, identify, and locate the bananaspecific type of phytoalexins, phenylphenalenones, in the R. similiscaused lesions of the plants. The striking antinematode activity of the phenylphenalenone anigorufone, its ingestion by the nematode, and its subsequent localization in lipid droplets within the nematode is reported. The importance of varying local concentrations of these specialized metabolites in infected plant tissues, their involvement in the plant's defense system, and derived strategies for improving banana resistance are highlighted.plant protection | induced plant defense | matrix-free LDI-MSI

The Impact of Plant-Parasitic Nematodes on Agriculture and Methods of Control

“…In a bioassay-based study, phenylphenalenones extracted from Musa spp. showed antinematode efects on R. similis which was demonstrated by nematode motility inhibition [64].…”

Publisher's Note

“…They are polycyclic aromatic compounds consisting of a tricyclic phenalene core structure with a keto functional group and a lateral phenyl ring (ring D) (see structure in Table 1). Because of their fungicidal (Otálvaro et al, 2007;Hidalgo et al, 2009) and nematicidal properties (Hölscher et al, 2014) and their inducibility after pathogen/herbivore attack (Luis et al, 1994;Jitsaeng and Schneider, 2010;Otálvaro et al, 2010), phenylphenalenones play an important role as phytoalexins in the chemical defense of Musa plants. The physiological and/or ecological importance of these metabolites in the three other plant families has yet to be explored, although their antioxidant capacity could be one of the reasons they are produced (Blokhina et al, 2003;Duque et al, 2010;Brewer, 2011).…”

The Intramolecular Diels-Alder Reaction of Diarylheptanoids — Quantum Chemical Calculation of Structural Features Favoring the Formation of Phenylphenalenones

“…Phenylphenalenones are a group of polycyclic plant natural products mainly occurring in the Haemodoraceae [1][2][3][4] and the Musaceae [5][6][7][8]. There is ample evidence that the biosynthesis of phenylphenalenones, first discussed by Thomas in 1961 [9], involves a diarylheptanoid, which undergoes cyclization to form the substituted tricyclic phenylphenalenone.…”

“…The conversion could proceed either by chemical reaction in vitro [10], starting from compound 1a, or in vivo after administration to plant material [11]. [2][3][4][5][6][7][8][9][10][11][12][13] C]1-(3,4-Dihydroxyphenyl)-7-phenylhepta-4,6-dien-3-one (1a), when administered to cultured roots of Anigozanthos preissii, was smoothly converted to [8][9][10][11][12][13] C]anigorufone [11]. …”