Transcriptional responses of catalase genes in maize seedlings exposed to cereal aphids' herbivory

The performed study was aimed at assessing the influence of two species of cereal aphids (bird cherry-oat aphid, Rhopalosiphum padi L. and grain aphid, Sitobion avenae F.) on the transcriptional responses of all three catalase (cat1, cat2, cat3) genes in seedling leaves of maize (Zea mays L.) genotypes varying in resistance levels to the insects' infestation. Furthermore, time-course generation of hydrogen peroxide (H2O2) in the aphid-attacked plants was estimated. Colonization experiments were conducted on 14 day-old seedlings of six selected Z. mays genotypes (Tasty Sweet and Zlota Kariowa - susceptible; Nana and Touran - moderately resistant; Ambrozja and Waza - highly resistant) that were artificially infested with adult apteral females of the tested hemipterans. Relative expression of target cat genes was monitored using real-time qRT-PCR technique, whereas hydrogen peroxide content was screened using a spectrophotometric microplate method. The obtained data indicated a crucial role of cat1 and cat2 genes in overcoming aphid-triggered disturbances in the redox homeostasis in the infested maize seedlings. It has been revealed dissimilar patterns of transcriptional reprogramming of the analysed cat genes in seedlings of resistant and sensitive maize cultivars. However, there were no significant changes in cat3 gene expression in maize plants in response to cereal aphids' attack. It was also found that all tested Z. mays genotypes responded an elevation in H2O2 content compared to the uninfested control, and this accumulation was linked with resistance degrees to the aphids' colonization. (C) 2015 Elsevier Ltd. All rights reserved.