Alterations in mineral and morpho-chemical composition in citrus plants in response to citrus tristeza virus

Abstract Citrus tristeza virus (CTV) alters the biochemistry and physiology of infected citrus plants and the mineral contents, reducing the defense response, making the plant more vulnerable and predisposing to other biotic factors. The study was carried out to investigate the biochemical alterations, enzymes, total phenolic compounds (TPC), total soluble sugar (TSS), antioxidant, and minerals profiling in healthy and CTV infected leaves. The TPC in infected citrus plants was lower both in leaf and bark. In contrast, healthy leaves and bark had significantly higher phenolic contents than CTV infected leaves and bark. The TSS were higher in healthy leaves than in diseased leaves and bark. Catalase (CAT) was the most abundant enzyme, followed by superoxide dismutase (SOD) and peroxidase (POD). The TSS amount in healthy leaves was 2.5 (°Brix), showed the higher ratio as compared to 1.7 (°Brix), in diseased leaves. While the higher TPC in healthy leaves 185.073 mg/100 g as compared to that of in diseased leaves, 92.228 mg/100 g, showed the role of TPC in resistance. Among different varieties, CAT in lemon was higher in healthy (57) and diseased plants (61.33) as compared to healthy and diseased plants of other varieties. Similarly, POD in lemon was also high in healthy (16) and diseased plants (20) compared to healthy and diseased plants of other varieties. Lemon also showed a high SOD in healthy (41.66 micro/ml/min) and diseased plants (47 micro/ml/min) compared to the healthy and diseased plants of other varieties. The minerals and heavy metals were plentiful in healthy and diseased plants, followed by iron, zinc, manganese, and copper. Citrus plants showed various physiological alterations due to CTV presence (transpiration rate, chlorophyll content, respiration rate, and photosynthetic rate) in both healthy and diseased plants. Furthermore, the leaf surface area of diseased plants was significantly less than healthy plants. Therefore, biochemical and mineral characterization to detect CTV will lead to new aspects of physiology, biochemistry and the symptoms development in diseased plants.