Abstract
Due to changing climate, flooding (waterlogged soils and submergence) becomes a major problem in agriculture and crop production. In the present study, the effect of waterlogging was investigated on peroxidases of maize (Zea mays L.) leaves. The plants showed typical adaptations to flooding stress, i.e., alterations in chlorophyll a/b ratios and increased basal shoot diameter. Seven peroxidase bands could be detected by first dimension modified SDS-PAGE and 10 bands by first dimension high resolution Clear Native Electrophoresis that altered in dependence on plant development and time of waterlogging. Native isoelectric focusing revealed three acidic to neutral and four alkaline guaiacol peroxidases that could be further separated by high resolution Clear Native Electrophorese in the second dimension. One neutral peroxidase (pI 7.0) appeared to be down-regulated within four hours after flooding, whereas alkaline peroxidases (pI 9.2, 8.0 and 7.8) were up-regulated after 28 or 52 h. Second dimensions revealed molecular masses of 133 kDa and 85 kDa for peroxidases at pI 8.0 and 7.8, respectively. Size exclusion chromatography revealed native molecular masses of 30–58 kDa for peroxidases identified as class III peroxidases and ascorbate peroxidases by mass spectrometry. Possible functions of these peroxidases in flooding stress will be discussed.
Highlights
Weather records documented a steady and significant increase in flooding events over the past six decades [1]
Two types of flooding are generally discriminated in the field: (1) waterlogging, in which root and some portion of the shoot are under water or the soil appears water saturated without free-standing water; and (2) complete submergence, where the whole plant is under water [3]
Gels used for guaiacol staining were generally loaded with 40 μg soluble proteins, except for proteins loaded on first dimension high resolution Clear Native Electrophoresis (hrCNE) (25 μg) used for the calculation of native molecular mass of peroxidases
Summary
Weather records documented a steady and significant increase in flooding events over the past six decades [1]. One of the key players in rice and wetland species grown under submerged conditions is ethylene, which induces (i) aerenchyma in the root cortex by programmed cell death; (ii) adventitious root growth and (iii) elongation of internode by regulation of gibberellic acid biosynthesis and sensitivity [3]. Class III peroxidases (secretory pathway) are antioxidative systems involved in several physiological functions including plant development, cell wall related processes and oxidative stress [17,18,19,20] Due to their reactive cycles, heme-containing peroxidases are involved in both production and detoxification of ROS and are affected under several stress conditions [19,20,21]. Possible functions of identified peroxidases in flooding stress will be further discussed in the results and discussion section
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