Journal of Phytopathology

AbstractZinnia peruviana (Asteraceae) is an annual flowering plant cultivated in various gardens of Mysore, the south of Karnataka state, India. During 2021, phytoplasma‐like symptoms such as virescence and phyllody were observed on Zinnia in Mysore local gardens. A total of 10 symptomatic and five asymptomatic samples were collected, and the DNA was amplified by PCR using primers specific to 16S RNA and secA genes. The nucleotide sequence analysis showed that the 16S RNA and SecA gene sequences were most similar to those of ‘Ca. P. aurantifolia’, with identities greater than 99%. The phytoplasma sequence from this study shared a common clade with ‘Ca. P. aurantifolia’ when phylogenetic analysis was done. Similarly, the reference sequences for the 16S rRNA and SecA region confirmed the identity of the phytoplasma associated with the leaves of Zinnia. This is the new host record for ‘Ca. P. aurantifolia’ (16SrII‐D) phytoplasma associated with Z. peruviana from India.

AbstractIncreasing incidences of phytoplasma infestations in Almond trees warrants the better management approach to prevent yield losses. Disease management rely on identification of the pathogen based on molecular profiling. The present study aimed, to identify the phytoplasma agent in almond trees and to measure the biochemical responses it causes in the host. Direct and Nested PCRs performed using phytoplasma specific primer pairs 16S rRNA, detected the presence of phytoplasma agent in symptomatic trees but not in symptomless trees. Phylogeny based on the sequence analysis revealed that the infecting agent was closely related to ‘Candidatus Phytoplasma phoenicium’ (16SrIX‐B subgroup). Then the study was carried out to determine the responses of physiological and biochemical mechanisms in almond trees infected with phytoplasma. Total chlorophyll and protein contents of infected almond trees were lower compared to healthy control, on the other hand, the levels of catalase and peroxidase activity increased in infected trees. Higher levels of stress‐related metabolites such as proline (20.53–39.23 μmol/g), phenol (3.00–4.44 mg GAE/g), salicylic (94.96–138.22 ng SA/mg protein) and jasmonic acid (965.86–1465.10 ng JA/mg protein) were observed in infected trees compared to asymptomatic trees, respectively in healthy and infected trees. The results showed that the Ca. P. phoenicium, which was detected for the first time in Türkiye, was able to change the physiological and biochemical mechanisms. The pathogenic agent could possess a potential danger in almond production areas. It is crucially important that this agent should be considered in certification programs.