Molecular characterization of 'Candidatus Phytoplasma solani' in celery: Case study in Futog

Abstract

'Candidates Phytoplasma solani', known by its trivial name stolbur phytoplasma, is a plant pathogen infecting numerous crops in Serbia. Celery plants with prominent leaf yellowing and chlorosis, sporadically with tissue necrosis, were observed during August 2020 in Futog, situated in Novi Sad suburbia in Vojvodina. Total of 12 sampled celery plants, 8 symptomatic and 4 asymptomatic ones, were analysed for 'Ca. P. solani' presence. All symptomatic celery plants were infected with stolbur phytoplasma according to the stoll 1 gene detection and therefore were further subjected to multigene molecular characterization on three genes: tuf, stamp and vmpl. Combining molecular tools PCR/RFLP and sequencing reviled two 'Ca. P. solani' multilocus genotypes in celery: tuf-b/Rqg31/V14 and tuf-b/ Rpm35/V14, present in 4 samples each. Obtained results of the strain genotyping are in concordance with previous data on the 'Ca. P. solani' diversity on celery, but supplemented with genotyping of the vmpl gene. Outbreak of stolbur phytoplasma in the assessed locality in Futog is linked to tuf-b epidemiological cycle correlated in Serbia mainly with weed Convolvulus arvensis which was present in the subjected celery plot, and could have been the phytoplasma inoculum source. Visual evaluation of the symptom occurrence suggests on 10-15% of 'Ca. P. solani' affected celery plants scattered throughout the plot corresponding to the pathogen dispersal in crop by cixiid planthoper Hyalesthes obsoletus (Hemiptera: Auchenorrhyncha) associated with C. arvensis, main vector of stolbur phytoplasma in Serbia.