Monitoring of the leaf biochemical compositions in Mexican lime (Citrus aurantifolia Swingle) during the progression of Witches’ Broom Disease of Lime (WBDL)

Witches’ broom disease of lime (WBDL), caused by ‘Candidatus Phytoplasma aurantifolia’, is major limiting factor for Mexican lime (Citrus aurantifolia Swingle) production in southern Iran. In this investigation, biochemical composition profiling of the healthy and infected rooted Mexican lime wasmonitored during WBDL progression (90-330 days) as well as to distinguish infected from healthy Mexican limes under greenhouse conditions. For this aim, stem cuttings is taken from healthy Mexican lime. After three months, half of Mexican lime cutting were inoculated by bark-grafting from WBDL-affected Mexican. Six healthy and infected plants were sampled 90, 150, 210, 270 and 330 days after inoculation with Phytoplasma. Pigments, total phenol, antioxidant capacity, soluble carbohydrate and starch content in leaves were measured. Results showed Phytoplasmal infection caused growth inhibition and reduced stem and root dry mater. Moreover, infection mostly caused to a marked decrease in pigments and significantly increased soluble carbohydrates and starch. In Mexican lime leaves, phenol contents and antioxidant capacity were increased after inoculation with Phytoplasma. In addition, the principal components analysis (PCA) revealed a clear distinction between the leaf biochemical profiles of healthy and infected plants during the progression of WBDL. In conclusion, this study provides new insights into the lime response to phytoplasma infection during the progression of WBDL. Finally, we showed that healthy plants can be isolated from infected plants using biochemical profiles.