Aphid-Triggered Changes in Oxidative Damage Markers of Nucleic Acids, Proteins, and Lipids in Maize (Zea mays L.) Seedlings

Abstract

Prior experiments illustrated reactive oxygen species (ROS) overproduction in maize plants infested with bird-cherry-oat (Rhopalosiphum padi L.) aphids. However, there is no available data unveiling the impact of aphids feeding on oxidative damages of crucial macromolecules in maize tissues. Therefore, the purpose of the current study was to evaluate the scale of oxidative damages of genomic DNA, total RNA and mRNA, proteins, and lipids in seedling leaves of two maize genotypes (Złota Karłowa and Waza cvs—susceptible and relatively resistant to the aphids, respectively). The content of oxidized guanosine residues (8-hydroxy-2′-deoxyguanosine; 8-OHdG) in genomic DNA, 8-hydroxyguanosine (8-OHG) in RNA molecules, protein carbonyl groups, total thiols (T-SH), protein-bound thiols (PB-SH), non-protein thiols (NP-SH), malondialdehyde (MDA) and electrolyte leakage (EL) levels in maze plants were determined. In addition, the electrical penetration graphs (EPG) technique was used to monitor and the aphid stylet positioning and feeding modes in the hosts. Maize seedlings were infested with 0 (control), 30 or 60 R. padi adult apterae per plant. Substantial increases in the levels of RNA, protein and lipid oxidation markers in response to aphid herbivory, but no significant oxidative damages of genomic DNA, were found. Alterations in the studied parameters were dependent on maize genotype, insect abundance and infestation time.

Expression of Thioredoxin/Thioredoxin Reductase System Genes in Aphid-Challenged Maize Seedlings

“…(highly resistant). Similarly, Sytykiewicz et al [ 22 ] elucidated that R. padi aphid infestation caused up to two times higher accumulation of MDA in maize leaves of susceptible Złota Karłowa cv., compared to more resistant Waza cv., and the highest increments at 24 h were noted. In addition, at this time point of the aphid infestation occurred the highest degree of the electrolyte leakage (indicating disruption of plasma membrane) in relation to the control.…”

“…Short-time increments in ROS level in the host tissues are linked to plant innate immunity responses toward adverse environmental stimuli; however, tolerance of the plant systems to long-term exposure to excessive ROS amounts is essential to maintain the functioning of numerous physiological processes. Our recent studies [ 20 , 22 ] demonstrated a significant increase in level of several biochemical markers of the oxidatively-induced damages of total and mRNAs, proteins and lipids in the aphid-stressed maize plants. Łukasik and Goławska [ 20 ] reported an increase in the content of malondialdehyde (MDA; biomarker of lipid peroxidation) in M. dirhodum -stressed seedlings of Ambrozja and Płomyk maize cvs, and the highest level of this compound at 48–96 h was recorded.…”

“…Previously, we revealed that R. padi and M. dirhodum aphid infestation induced accumulation of superoxide anion radicals and hydrogen peroxide in the maize seedlings, depending on the host and aphid genotypes, duration of infestation period and number of insects per plant [ 17 , 18 , 19 , 20 , 21 ]. Furthermore, we recorded profound increments in the content of several markers of oxidative damages of RNA, proteins and lipids in R. padi - or M. dirhodum -infested maize seedlings [ 21 , 22 ]. Based on our prior results [ 21 , 22 ] evidencing significant disturbances in the thiol metabolism in the aphid-stressed maize seedlings, we hypothesized that aphid infestation may modulate expression of the genes associated with functioning of Trx/TrxR system and/or total activity of TrxR in the maize plants.…”

“…Furthermore, we recorded profound increments in the content of several markers of oxidative damages of RNA, proteins and lipids in R. padi - or M. dirhodum -infested maize seedlings [ 21 , 22 ]. Based on our prior results [ 21 , 22 ] evidencing significant disturbances in the thiol metabolism in the aphid-stressed maize seedlings, we hypothesized that aphid infestation may modulate expression of the genes associated with functioning of Trx/TrxR system and/or total activity of TrxR in the maize plants. However, the involvement of Trx/TrxR system in plants exposed to environmental stimuli, remains largely unknown.…”

“…The EPG method enables real-time monitoring of changes in electrical signals (i.e., specific waveforms) that correspond to various feeding/probing behavior of piercing-sucking insects in the host plant tissues [ 23 , 24 ]. Previously [ 22 ], we assessed profound differences in EPG recordings of R. padi aphids in the seedlings of those two maize genotypes. Hence, comparison the EPG data derived from the two cereal aphid species ( M. dirhodum and R. padi ) would extend the knowledge regarding stylet positioning and feeding activities in both susceptible and relatively resistant maize varieties.…”