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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The current research addressed the effect of fertilizers containing Ca2+ and Mg2+ on cassava (Manihot esculenta Crantz) storage roots (CSRs) during postharvest physiological deterioration (PP D). Cassava PP D tolerant and susceptible genotypes were grown in pots and treated with fertilizers containing Ca2+ or Mg2+. Eight months after planting, CSRs were harvested and stored at room temperature for 30 d. Morphological changes, antioxidant activities, mineral content, and starch content were determined. The results indicated that application of Ca2+ and Mg2+ fertilizers delayed PP D for >10 d in the susceptible genotype (SC5), but Mg2+ fertilizer elevated PP D in the tolerant genotype (QZ1). The Ca2+ fertilizer significantly increased fresh weight. A significant decrease in starch content in CSRs of SC5 treated with Mg2+ fertilizer was observed. The Mg2+ fertilizer slightly enhanced Ca2+, Mg2+, and K+ contents in both genotypes. In addition, Ca2+ fertilization led to a significant increase in H2O2 content and subsequent elevation of activities of catalase and peroxidase in both genotypes, especially at harvest. Our findings suggest that soil fertilization with fertilizers containing Ca2+ and Mg2+ may play a distinct role in PP D delay in CSRs. [ABSTRACT FROM AUTHOR]