Photochemical performance and source-sink relationships in galls induced by Pseudophacopteron longicaudatum (Hemiptera) on leaves of Aspidosperma tomentosum (Apocynaceae)

Abstract

The establishment of the galling insect generates a biotic stress that leads to tissue transformation. However, galls can maintain chlorophyll (Chl) and consequently photosynthesize. Herein, we evaluated the consequences of the biotic stress generated by the galling insect Pseudophacopteron longicaudatum on photosynthetic rate during the leaf galls development on Aspidosperma tomentosum. In addition, we quantified polysaccharides and water content in order to evaluate the capacity of gall tissues to drain photoassimilates. The non-galled leaves contained more Chl and carotenoids per gram of fresh mass. Galls had lower values of maximum PSII quantum yield, fluorescence decline ratio, and nonphotochemical quenching compared to non-galled tissue. These results showed a significant reduction of photosynthesis photochemistry in galled tissues although total soluble sugar did not differ between gall and non-galled leaves. Water-soluble polysaccharides, relative water content, and leaf specific mass were significantly higher in galls and increased through their development, suggesting a sink relationship.

Keywords

• gall photosynthesis
• green island
• herbivory
• kautsky effect
• oxidative stress