Ulubaş Serçe, Çiğdem

Phytoplasmas cause infections in numerous plants in agricultural ecosystems, causing significant yield and quality losses in products. In recent years, it has been known that diseases caused by phytoplasmas cause economic losses in eggplant (Solanum melongena L.) cultivation. In Turkey, research on infections caused by phytoplasmas in eggplant growing areas is quite limited. This study was carried out to detect phytoplasma infections symptomatologically and molecularly in eggplant production areas in Şanlıurfa province. Fourteen samples were collected from eggplants exhibiting symptoms such as witches’ broom, flower abnormalities (virescence, phyllody), elongation of the pedicle, arising of new shoots from flower parts, yellowing and proliferation. Phytoplasma infection was detected in 8 symptomatic samples using 16S rRNA-specific primers, P1/P7 and R16F2n/R16R2, by direct and nested PCR. Sequence information of fragments obtained as a result of molecular studies was extracted and BLAST analyses were performed. According to nucleotide sequence similarity in the 16S rRNA gene region, it was determined that the genetic group of phytoplasma causing infection in eggplant was related to ‘Candidatus Phytoplasma solani’ (CaPsol) belonging to 16SrXII-A subgroup with 98% sequence identity. To our best knowledge, this study suggests comprehensive symptomatic diagnosis of CaPsol infecting eggplants in Türkiye.

The apple orchards in Niğde, Turkiye were surveyed for ‘Candidatus Phytoplasma mali’ associated with apple proliferation disease, and the suspicious samples were tested by PCR-RFLP methods. A comprehensive study was conducted which included sampling from a total of 19 orchards from four different districts. The samples were collected according to the major symptoms of phytoplasma disease which were foliar reddening, witches’ brooms, leaf rosettes, yellowing, longer peduncles and development of undersized fruits. It was determined that six out of 62 plant samples were infected with pyhtoplasma. Also, two out of six infected samples were determined as infected by ‘Ca. P. mali’ and unexpectedly four out of six infected samples were determined as infected by ‘Ca. P. prunorum’ associated with European Stone Fruit Yellows disease. Even if the incidence of the disease (9.7%) was low, the characterized phytoplasmas were considered as a significant potential threat for these locations. Key words: PCR-RFLP Survey, Niğde, Apple proliferation, European stone fruit yellows

Aims: In this study, the best sampling time and tissues for phytoplasma detection in twenty pear trees (cv. Deveci) infected by ‘Candidatus Phytoplasma pyri’, causal agent of pear decline disease, in Bursa province of Turkey were investigated.Methods and Results: Sampling was done throughout the year in leaf midribs, shoot and root tissues, where as the flower tissues were tested once a year in March and fruit tissues in September. All samples were analyzed by nested-PCR using P1/P7 and fU5/rU3 universal primer pairs. Nested PCR products were digested with RsaI and SspI restriction enzymes. The results revealed that the detection rate of ‘Ca. P. pyri’ in different plant tissues was greatly depending on the sample collection period. The fruit tissues, which were only sampled in September due to the ripening time of Deveci pear cultivar in Bursa, showed the highest detection rate of ‘Ca. P. pyri’ (100%) followed by flower tissues (75%). The average detection rate in root, shoot tissues and leaf midribs was found as 43.75, 39.58 and 16.25%, respectively. The present results showed that the best plant tissues for detecting ‘Ca. P. pyri’ in pear trees were fruit columella and flowers. The highest detection rate of this phytoplasma in root tissues was found from November to March, whereas it could be detected whole year around except summer months in shoot samples in Turkey.Conclusions: For 'Candidatus Phytoplasma pyri', detection, if there is no seasonal limitation for testing, the most suitable tissues are fruits and flowers. When it comes to testing throughout the year, the most suitable tissues were determined as the root, the phloem and cambium layer of the shoots and the leaves, respectively.Significance and Impact of the Study: This study on seasonal variations of ‘Candidatus Phytoplasma pyri’ in different pear tissues has been first time investigated in Turkey. This preliminary data provides important knowledge on molecular detection of Ca. P. pyri, causal agent of pear decline disease for further studies and sertification-quarantine programmes of pear trees in Turkey.