Phenolic substances and cyanogenesis in galled and non-galled tissue of the fern species Microgramma vacciniifolia

Abstract

Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midge-induced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.

Alterations induced by Tortrimosaica polypodivora on the stems of Microgramma vacciniifolia: simple or complex galls?

“…A previous comparison of phenolic substances that accumulated in the NGSs and galls induced by T. polypodivora revealed that they had similar accumulated phenolic substances (Santos et al 2022). On the other hand, in the same comparisons, the galls induced by P. microgrammae showed differences with the NGSs (Santos et al 2022), revealing that the latter species induced alterations in polyphenol biosynthesis in the same host plants.…”

“…Furthermore, the maintenance of an intact meristele is related to the phenolic accumulation in the circumendodermal band walls, which were usually related to the defense against herbivores and pathogens (Feeny 1976;Tempel 1981), and removal of excessive reactive oxygen species (Tuladhar et al 2021), avoiding premature cell senescence in the galls (Isaias et al 2018;Ferreira et al 2018;Guedes et al 2022). A previous comparison of phenolic substances that accumulated in the NGSs and galls induced by T. polypodivora revealed that they had similar accumulated phenolic substances (Santos et al 2022). On the other hand, in the same comparisons, the galls induced by P. microgrammae showed differences with the NGSs (Santos et al 2022), revealing that the latter species induced alterations in polyphenol biosynthesis in the same host plants.…”