Mineral deficiencies effect on resistance-related enzymes activities in tomato leaves
2018
Alsharafa, Khalid Y.
Crop yield and quality are limited by different biotic and abiotic factors. This study focused on the ability of phenylalanine ammonia-lyase, ascorbate peroxidase and polyphenol oxidase to impart resistance to mineral deficiencies. Tomato plants (Lycopersicon esculentum L.) were grown for 48, 72 and 96 hr with different specific deficiencies of minerals, including Mg²⁺, Ca²⁺, Fe²⁺, PO₄²⁻, K⁺, NO₃⁻ and SO₄²⁻, and then the soluble protein content and enzymatic activities (phenylalanine ammonia-lyase, polyphenol oxidase and ascorbate peroxidase) were analyzed. The impact of the mineral deficiencies varied in the tomato leaves. Mineral deficiencies that caused early significant protein accumulation were detected in tomato leaves grown in hydroponic cultures deficient in Ca²⁺, PO₄²⁻ and NO₃⁻ after 48, 72 and 96 hr of incubation, whereas the soluble protein level was drastically reduced in tomato leaves grown in cultures deficient in Mg²⁺, Fe²⁺, K⁺ and SO₄²⁻ that reveal remarkable time-dependent increase in resistance-related enzymes' activities. The resistancerelated enzymes' activities were not correlated with the soluble protein levels. These findings suggest that these activities depend on the amount of foliar nutrients, particularly Mg²⁺, Fe²⁺, K⁺ and SO₄²⁻. These nutrients act synergistically on the phenolic compound biosynthesis and degradation-dependent enzymes, and this synergistic process could be considered as a mechanism of acclimation for plants against specific mineral deficiencies.
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