Abstract
Thioredoxins (Trxs) and thioredoxin reductases (TrxRs) encompass a highly complex network involved in sustaining thiol-based redox homeostasis in plant tissues. The purpose of the study was to gain a new insight into transcriptional reprogramming of the several genes involved in functioning of Trx/TrxR system in maize (Zea mays L.) seedlings, exposed to the bird cherry-oat aphid (Rhopalosiphum padi L.) or the rose-grass aphid (Metopolophium dirhodum Walk.) infestation. The biotests were performed on two maize genotypes (susceptible Złota Karłowa and relatively resistant Waza). The application of real-time qRT-PCR technique allowed to identify a molecular mechanism triggered in more resistant maize plants, linked to upregulation of thioredoxins-encoding genes (Trx-f, Trx-h, Trx-m, Trx-x) and thioredoxin reductase genes (Ftr1, Trxr2). Significant enhancement of TrxR activity in aphid-infested Waza seedlings was also demonstrated. Furthermore, we used an electrical penetration graph (EPG) recordings of M. dirhodum stylet activities in seedlings of the two studied maize varieties. Duration of phloem phase (E1 and E2 models) of rose-grass aphids was about three times longer while feeding in Waza plants, compared to Złota Karłowa cv. The role of activation of Trx/TrxR system in maintaining redox balance and counteracting oxidative-induced damages of macromolecules in aphid-stressed maize plants is discussed.
Highlights
Plant thioredoxins (Trxs) are a diverse group of oxidoreductases involved in the cleavage of a disulfide bond between the cysteine residues in the target proteins [1,2]
The oxidized thioredoxins may undergo a reversible reduction reaction catalyzed by thioredoxin reductases (TrxRs)
Two Trx/TrxR systems have been found; one of them is linked to ferredoxin-thioredoxin reductase (FTR; EC 1.8.7.2), and the second one is associated with NADPH-dependent thioredoxin reductase (TrxR; EC 1.8.1.9) [8,9]
Summary
Plant thioredoxins (Trxs) are a diverse group of oxidoreductases involved in the cleavage of a disulfide bond between the cysteine residues in the target proteins [1,2]. Two Trx/TrxR systems have been found; one of them is linked to ferredoxin-thioredoxin reductase (FTR; EC 1.8.7.2), and the second one is associated with NADPH-dependent thioredoxin reductase (TrxR; EC 1.8.1.9) [8,9]. The Trx/TrxR systems play a pivotal role in restoring intracellular redox homeostasis during both physiological state of the cells and under exposure to environmental stresses, limiting oxidative-associated damages to crucial macromolecules in the plants [10,11]. There is scarce information regarding transcriptional regulation of the genes encoding thioredoxins and thioredoxin reductases in plant tissues [12]
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