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

Abstract

‘Candidatus 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 stol11 gene detection and therefore were further subjected to multigene molecular characterization on three genes: tuf, stamp and vmp1. 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 vmp1 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.

‘Candidatus Phytoplasma solani’, poznata po trivijalnom nazivu stolbur fitoplazma, biljni je patogen koji inficira brojne kulture u Srbiji. Biljke celera sa izraženim žutilom i hlorozom listova, sporadično i sa nekrozom tkiva, uočene su u avgustu 2020. u Futogu, predgrađu Novog Sada u Vojvodini. Ukupno 12 uzoraka celera, 8 simptomatičnih i 4 asimptomatične biljke, analizirane su na prisustvo ‘Ca. P. solani’. Svi simptomatični uzorci su se pokazali inficiranim stolbur fitoplazmom na osnovu analize stol11 gena i dalje su molekularno okarakterisani na 3 gena: tuf, stamp i vmp1. Kombinacijom molekularnih tehnika PCR/RFLP i sekvenciranja utvrđeno je prisustvo dva ‘Ca. P. solani’ multigenska genotipa, tuf-b/Rqg31/V14 i tuf-b/Rpm35/V14, prisutnih u po četiri uzorka. Dobijeni rezultati genotipizacije uzoraka stolbur fitoplazme odgovaraju prethodnim podacima o diverzitetu ovog patogena na celeru u Srbiji i dopunjeni su sa genotipizacijom vmp1 gena. Pojava stolbur fitoplazme u Futogu je vezana za tuf-b epidemiologiju, koja uglavnom izvire iz korovske vrste Convolvulus arvensis (poponac), koja je bila prisutna u istraživanom zasadu celera i mogla je biti izvor inokuluma. Vizuelna procena pojave simptoma pokazala je 10-15% prisustva simptomatičnih biljaka celera, nepravilno raspoređenih unutar zasada što ukazuje da je odgovorni vektor najverovatnije cikada Hyalesthes obsoletus (Hemiptera: Auchenorrhyncha) asocirana sa poponcem, najznačajniji vektor stolbur fitoplazme u Srbiji.