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BackgroundThe effects of exogenously applied H2O2 on growth, water status, the mineral ion content (Na+, K+, Ca2+, Mg2+ and Cu2+), proline, total sugars and soluble proteins were assessed in leaves of maize (Zea mays L.) cultivars, Akpinar and Pegaso exposed to excess copper (0.5 mM). Seedlings were grown in equal-sizes plastic pots and irrigated with Hoagland nutrient solution containing H2O2 or/and copper. Different treatments taken for pot experiments were named as the control (C), H2O2 treatment only (H2O2), excess Cu (Cu) and, Cu stress combined with H2O2 pretreatment (Cu + H2O2).ResultsTreatment of H2O2 caused the increases in growth, water content, mineral concentration, proline, total sugar and soluble protein contents compared to the control groups in the leaves of both cultivars. Yet excess copper caused reductions in the growth, leaf water potential, Na+, K+, Ca+, Mg2+ concentrations and soluble protein levels but increases in proline, total soluble sugars and Cu2+ contents compared to the control group. Dry matter, leaf water potential and mineral content of Cu + H2O2 group revealed a lower decrease than Cu group ones. A higher increase was also observed in proline and total sugar contents of Cu + H2O2 group than Cu group ones in both cultivars.ConclusionsThese data revealed that exogenous H2O2 might increase the dry matter production and the mineral ion distribution in maize seedlings. Moreover, osmotic regulation might be involved in alleviation of copper toxicity of maize leaves by pretreatment of H2O2.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-26) contains supplementary material, which is available to authorized users.

Phosphorus (P), nitrogen (N), carbon (C), and sulfur (S) contents of the leaves and specific leaf area (SLA), leaf mass per area (LMA), and N and P resorption were researched in Vaccinium arctostaphylos L. and Vaccinium myrtillus L., economically important for the East Black Sea region of Turkey. The leaves samples were collected from Solaklı Valley in Trabzon at 60 to 1800 m for V. arctostaphylos L. and 2100 to 2300 m for V. myrtillus L. The N, C, and S contents were determined by Dumas method and P concentration by the stannous chloride method. Nutrient contents, SLA, and LMA in leaves and N, P, organic matter, and pH in soil were measured. The foliar N, P, C, and S contents of the plants depending on the altitude gradient were statistically significant. N and S contents were significantly important during the growing season for both species. There were significant differences in terms of N and P proficiency for both species. Resorption values of V. myrtillus L. were found to be within the normal limits and the resorption efficiency values increased in parallel with the altitude changes. N resorption levels of V. arctostaphylos at lower (60 m) and higher (1800 m) altitudes were below the declared limits. It was also seen that while N proficiency showed significant increase, P proficiency decreased depending on the altitude. Both N and P proficiency for V. myrtillus decreased with the altitude increase.

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Cytochrome P450 monooxygenases are one of the largest heme-containing protein groups, and the majority of them catalyze hydroxylation reactions dependent on nicotinamide adenine dinucleotide phosphate and oxygen. Cytochrome P450 (CYP) enzymes function in a wide range of monooxygenation reactions essential in primary and secondary metabolism in plants. Camellia sinensis (L.) Kuntze is a commercially and economically valuable plant due to its medicinally important secondary metabolites and as a beloved beverage. Cytochrome P450 monooxygenases play a significant role in the biosynthesis of a variety of secondary metabolites in tea. Although the biosynthesis of secondary metabolites has been investigated in detail, there have been limited studies conducted on identifying the genetic mechanisms of CYP-catalyzed secondary metabolic pathways in the C. sinensis (tea) plant. In our study, we characterized a putative C. sinensis (L.) Kuntze cytochrome P450 monooxygenase gene (Csp450), which has 1759 bp full-length cDNA with 49 bp of 5ʹ and 183 bp of 3ʹ untranslated regions. The CDS of the gene is 1527 bp and 508 amino acids in length. BLAST results of the deduced amino acid sequence revealed a high similarity with the CYP704C1-like superfamily. Preharvest period gene expression analysis from May, July, and September did not show any difference.