Hemicelluloses and associated compounds determine gall functional traits

Abstract

The intriguing questions concerning gall development refer to the processes of the remodelling of the host plant organ. Such processes involve the restructuring of cell walls and can be influenced by phenolics, indole‐3‐acetic acid (IAA) and reactive oxygen species (ROS). Alterations in cell walls demand the interference in the coupling of cellulose fibrils and hemicelluloses (xyloglucans) at specific stages of gall development. In addition to cell wall remodelling, hemicelluloses, such as the, xyloglucans and heteromannans can act as reserve carbohydrates, while xylans provide rigidity to the secondary cell walls. Developmental traits of the lenticular, fusiform and globoid galls on Inga ingoides (Fabaceae) were analysed using anatomical, cytometric, histochemical and immunocytochemical tools. Phenolics, IAA and ROS accumulated in similar gall tissue compartments, and may have influenced the restructuring of hemicelluloses and pectins. Contrary to expectations, cell wall flexibility regarding the dynamics of xyloglucans and cellulose fibrils does not relate to a temporal scale. The detection of xyloglucans in nutritive cell walls relate to carbohydrate nutritional resources to the galling insect, while xylans were associated to the lignified cell walls. Heteromanans were not detected, either in non‐galled or galled tissues. The patterns of cell expansion during gall development relied on the relationship among phenolics, ROS and IAA with the hemicelluloses (xyloglucans and xylans) and cellulose fibrils. Although cell wall dynamics is specific to each gall morphotype in I. ingoides, the xyloglucans function as carbohydrate reserve to the gall inducers, which constitutes a functional trait common to the three morphotypes.

Structural and Nutritional Peculiarities Related to Lifespan Differences on Four Lopesia Induced Bivalve-Shaped Galls on the Single Super-Host Mimosa gemmulata

“…Recently, the xyloglucans were reported as reserve carbohydrates in cell walls of nematodeinduced galls on Miconia spp. (Melastomaceae) (Ferreira et al, 2020), and cell walls of the common storage and of the typical nutritive tissues of Cecidomyiidae-induced galls on Inga ingoides (Fabaceae) (Bragança et al, 2020a). Herein, the epitopes of xyloglucans labeled by LM15 in the common storage tissue of the BLG and the GG, and in the schlerenchymatic layers of the LG and GLG can influence the dynamics of cell wall expansion and rigidity.…”

“…The cells of the typical nutritive tissue have conspicuous nuclei, fragmented vacuoles, and dense protoplasm, which accumulate energetic metabolites related to the nutrition of the gall inducer (Bronner, 1992;Oliveira et al, 2010Oliveira et al, , 2011aFerreira et al, 2015). The additional accumulation of carbohydrates in cell walls have been recently evaluated in nematode-induced galls (Ferreira et al, 2020) and in insect-galls (Bragança et al, 2020a), with peculiarities regarding the type and distribution of hemicellulose epitopes. The hemicelluloses, xyloglucans and heteromannans, integrate the primary or secondary cell walls, may regulate cell expansion (Cosgrove, 2016(Cosgrove, , 2018, and have also been related to the galling organism maintenance (Bragança et al, 2020a;Ferreira et al, 2020).…”

“…The additional accumulation of carbohydrates in cell walls have been recently evaluated in nematode-induced galls (Ferreira et al, 2020) and in insect-galls (Bragança et al, 2020a), with peculiarities regarding the type and distribution of hemicellulose epitopes. The hemicelluloses, xyloglucans and heteromannans, integrate the primary or secondary cell walls, may regulate cell expansion (Cosgrove, 2016(Cosgrove, , 2018, and have also been related to the galling organism maintenance (Bragança et al, 2020a;Ferreira et al, 2020). In an overall analysis, the storage and nutritive tissues accumulate different metabolites in Cecidomyiidae galls (Bronner, 1992;Moura et al, 2008;Oliveira et al, 2010) but can perform specific functions in the diverse host plant-galling insect systems (Amorim et al, 2017;Bragança et al, 2017).…”

“…Accordingly, the longer the galling insect stay inside the gall, the higher the gall demand is (Carneiro et al, 2017), therefore, the long-life cycle of the galling insect may determine more complex gall structural profiles (Gonçalves et al, 2005). Such presumption may be analyzed in the nutritional perspective, and the accumulation of energetic resources in gall storage tissues can be higher, the longer the gall lifespan is, which may be elegantly evaluated in superhost plants with several associated galling-insects (Formiga et al, 2014;Amorim et al, 2017;Bragança et al, 2020a;Costa et al, submitted).…”