Comparisons of photosynthetic parameters in tomato genotypes with differing levels of fatty acid desaturation and aphid resistance

Fatty acid desaturases (FADs), which introduce double bonds into the acyl chains of fatty acids, play important roles in plant responses to a variety of stresses. Loss of function of Fatty Acid Desaturase 7 (FAD7) in tomato (Solanum lycopersicum) enhances resistance against potato aphids (Macrosiphum euphorbiae). Our hypothesis is that mutations in FAD7 perturb photosynthesis by altering the lipid composition of chloroplast membrane; limitations in photochemical quenching could in turn lead to increased ROS production and enhanced ROS-dependent defensive signaling. To test the influence of FAD7 on photosynthesis, we compared gas exchange, chlorophyll fluorescence, and chlorophyll content in isogenic tomato genotypes with normal and impaired FAD7 function.  Results indicate reduced chlorophyll content in mutant plants, as well as differences in photosynthetic parameters. These data provide a foundation for further investigations of the relationship between photosynthetic activity and ROS accumulation in FAD7 mutants.