Mineral deficiencies influence on tomato leaves: pigments, hydrogen peroxide and total phenolic compounds contents

The detection of hydrogen peroxide, chlorophyll pigments, anthocynin, carotenoids, total phenolic compounds and lipid peroxidation levels as potential stress signaling molecules in tomato (Lycopersicon esculentum Mill.) leaves in response to specific mineral deficiency were studied. The stress signaling molecules were measured in the plant leaves at different growth time points cultured in specific mineral deficient nutrient solutions. The results showed that hydrogen peroxide was significantly increased after 48 and 72h of growth in NO3 ̄ and S deficient nutrient solutions. While the significant accumulation of H2O2 in the plant leaves was observed after 72h and 96h of growth in K deficient nutrient solution. In the case of Mg and Fe deficiency the significant accumulation was observed after 72h cultivation. The only significant reduction in chlorophyll a content was detected after 96h cultivation under Mg specific deficiency with no significant changes due to NO3 , SO4 , Fe, K, Ca and PO4 2 ̄ deficiencies. Meanwhile, chlorophyll b contents were significantly reduced in the plant leaves grown for 48h under Mg and Ca specific mineral deficiency. Longer cultivation in Mg dificient hydroponic culture for 96h resulted in 215% increment in chlorophyll b content. No significant changes in chlorophy b contents were detected in hydroponic cultures dificient in NO3 , SO4 , Fe, and PO4 . Impose of minerals deficiencies on anthocyanins and carotenoids contents were showed parallel changes. Both increased significantly in response to PO4 2 ̄ and NO3 ̄ specific deficiencies after 48h and in the case of Mg deficiency after 72h. Meanwhile, SO4 deficiency caused the significant increase of both after 72h and 96h. Regarding TPC the results clarified that Mg, Ca and K specific deficiencies caused significant reductions that appeared after 48h. In contrast, S deficiency caused significant increase in TPC values after 72h. On the other hand, the estimated levels of MDA showed significant increment under Ca and K and PO4 2 ̄ specific deficiencies at all time points while in the case of Mg and Fe deficiencies the increment was first reported after 48h and with the later one (Fe) the increment continues up to 96h. These results indicate that some of presented metabolites could be used as stress markers. These results support the possible role of anthocyanins, carotenoids, hydrogen peroxide, total phenolic compounds contents and MDA as early signaling metabolites in tomato plants under specific mineral deficiency.