Functional implications of cell wall composition in leaf-folding galls induced by Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae) on Ficus benjamina L. (Moraceae)

Abstract

Ficus benjamina - Gynaikothrips uzeli system was herein used as the study model to test if and to what degree the leaf-folding and establishment of the colony of thrips demand alterations in cell wall flexibility and porosity, which were mapped by immunocytochemical techniques. Cell wall flexibility was related to arabinans at the epidermis level, while the balance of methyl-esterified and non-esterified forms of homogalacturonans in the cell walls of the homogeneous parenchyma provided a balance between flexibility and rigidity. In this specific gall morphotype, arabinans contribute to regulating water balance and nutrient transport while also providing extra structural support to the inner epidermis of the gall, which is the area most affected by the thrip colony. The methyl-esterified homogalacturonans also improved the porosity necessary for translocating nutrients and water from cell-to-cell. Some degree of rigidity in gall tissues was guaranteed by the xyloglucans, whose epitopes were labeled in the homogeneous parenchyma cells. As expected, the dynamics of pectins and hemicelluloses in the G. uzeli on F. benjamina system implied in cell expansion and porosity, which related to leaf folding and apoplastic translocation of water and nutrients.