Transcriptional reprogramming of genes related to ascorbate and glutathione biosynthesis, turnover and translocation in aphid-challenged maize seedlings

Aphids are pierce-sucking insects that severely affect redox homeostasis in the host tissues. Reduced ascorbate (AsA) and glutathione (GSH) serve as multifunctional molecules involved in constituting sophisticated plant defense responses to aphids' herbivory. This survey aimed to decipher transcriptional responses of forty-one genes associated with AsA and GSH biosynthesis, turnover and translocation in maize (Zea mays L.) seedlings infested with two hemipterans' species: bird cherry-oat aphid (Rhopalosiphum padi L.) and grain aphid (Sitobion avenae F). Cereal aphids' attack substantially stimulated the expression of fifteen maize genes - encoding l-galactose dehydrogenase (GalDH), l-galactono-1,4-lactone dehydrogenase (GLDH), ascorbate oxidase (AO), glutamate-cysteine ligase (GCL), glutathione synthetase (GS), two isozymes of glutathione peroxidase (GPX1, GPX3), five isoforms of glutathione transferase (GST9, GST11, GST16, GST31, GST38) and three GSH transporters (ABCC2, ABCC6, GT1). Transcriptional alternations of these genes were dependent on maize genotype, insect species, duration of infestation and aphids' abundance. Specific patterns of genes' expression as well as total activity of the corresponding enzymes in insect-challenged maize seedlings (cvs Ambrozja and Tasty Sweet, which are relatively resistant and susceptible, respectively) highlighted the molecular background of crucial part of the complex antioxidative responses of maize model plant toward cereal aphids' colonization.