ABSTRACT
The major aim of the present study was to investigate the influence of juglone (JU; 5-hydroxy-1,4-naphthoquinone) treatments on the expression level of Cat1, Cat2 and Cat3 genes, encoding the respective catalase isozymes in maize (Zea mays L.) and wheat (Triticum aestivum L.) seeds. In parallel, germination efficiency, catalase (CAT) activity and hydrogen peroxide (H2O2) content in juglone-exposed cereal seeds were assessed. Juglone applications significantly stimulated abundance of three target catalase transcripts as well as induced CAT activity and generation of H2O2 in both maize and wheat kernels. Furthermore, germination process of juglone-affected maize seeds was more severe suppressed than in case of wheat kernels. The role of juglone in triggering the oxidative stress as well as antioxidative responses in seeds of the studied model cereal species are discussed.
Subject(s)
Catalase/genetics , Gene Expression Profiling/methods , Naphthoquinones/pharmacology , Plant Proteins/genetics , Seeds/drug effects , Transcriptome/drug effects , Triticum/drug effects , Zea mays/drug effects , Catalase/biosynthesis , Enzyme Induction/drug effects , Gene Expression Regulation, Plant/drug effects , Germination/drug effects , Hydrogen Peroxide/metabolism , Isoenzymes , Plant Proteins/biosynthesis , Seeds/enzymology , Seeds/genetics , Triticum/enzymology , Triticum/genetics , Zea mays/enzymology , Zea mays/geneticsABSTRACT
Despite senescence-induced chlorophyll depletion in plants has been widely studied, the enzymatic background of this physiologically regulated process still remains highly unclear. The purpose of this study was to determine selected biochemical properties of partially purified fractions of chlorophyllase (Chlase, chlorophyll chlorophyllido-hydrolase, EC 3.1.1.14) from leaves of three Prunus species: bird cherry (Prunus padus L.), European plum (Prunus domestica L.), and sour cherry (Prunus cerasus L.). Secondarily, this report was aimed at comparing seasonal dynamics of Chlase activity and chlorophyll a (Chl a) content within investigated plant systems. Molecular weight of native Chlase F1 has been estimated at 90 kDa (bird cherry) and approximately 100 kDa (European plum and sour cherry), whereas molecular mass of Chlase F2 varied from 35 kDa (European plum) to 60 kDa (sour cherry). Furthermore, enzyme fractions possessed similar optimal pH values ranging from 7.6 to 8.0. It was found that among a broad panel of tested metal ions, Hg(+2), Fe(+2), and Cu(+2) cations showed the most pronounced inhibitory effect on the activity of Chlase. In contrast, the presence of Mg(+2) ions influenced a subtle stimulation of the enzymatic activity. Importantly, although Chlase activity was negatively correlated with the amount of Chl a in leaves of examined Prunus species, detailed comparative analyses revealed an incidental decrement of enzymatic activity in early or moderately senescing leaves. It provides evidence that foliar Chlase is not the only enzyme involved in autumnal chlorophyll breakdown and further in-depth studies elucidating this catabolic process are required.
Subject(s)
Carboxylic Ester Hydrolases/chemistry , Chlorophyll/chemistry , Plant Leaves/enzymology , Plant Proteins/chemistry , Prunus/enzymology , Carboxylic Ester Hydrolases/isolation & purification , Cations, Divalent , Chlorophyll A , Copper/chemistry , Enzyme Assays , Hydrogen-Ion Concentration , Iron/chemistry , Kinetics , Magnesium/chemistry , Mercury/chemistry , Molecular Weight , Plant Leaves/chemistry , Plant Leaves/classification , Plant Proteins/isolation & purification , Prunus/chemistry , Prunus/classification , Species Specificity , Time FactorsABSTRACT
Pea aphid fed on a high-saponin line of alfalfa showed reduction of reproduction and survival, and disturbance in development of its population. This line negatively influenced aphid probing behaviour, particularly prolonging the non-probing period and probing of the peripheral tissues (epidermis and mesophyll) and shortening the period of phloem sap ingestion. The high-saponin line of alfalfa differed from the low-saponin one by the presence of zanhic acid tridesmoside and a higher level of 3-GlcA,28-AraRhaXyl medicagenic acid glycoside. The saponins incorporated into sucrose-agarose gels significantly reduced number of the aphid probes into the gels and extended their duration in comparison to the control gels (without tested compounds). Role of zanhic acid tridesmoside and 3-GlcA,28-AraRhaXyl medicagenic acid glycoside as potential factors for partial resistance of alfalfa towards the pea aphid is discussed.
