Asma yaprak kıvırcıklık virüsü-1 Türk izolatlarının Genetik Varyasyon ve Rekombinasyon Analizleri

Asma yaprak kıvırcıklık virüsü -1 (Grapevine leafroll-associated virus 1-GLRaV-1), asma yaprak kıvırcıklık hastalığına (Grapevine leafroll disease-GLRD) neden olan etmenler arasında yer almakta olup dünya çapında virüs kökenli bağ hastalıkları arasında önem derecesi yüksektir. Bu çalışmada, Türkiye’den izole edilen GLRaV-1’ in yaygınlık derecesi, genetik varyasyonu ve rekombinasyon olayları araştırılmıştır. İlk olarak, farklı bölgelerden toplanan 197 adet asma örneği serolojik olarak test edilmiştir. Test edilen örneklerden 109 adetinin (%55.32) GLRaV-1 ile infekte olduğu tespit edilmiştir. İnfekte olduğu tespit edilen bu örnekler arasından her bir coğrafik bölgeyi temsil eden 9 adet izolat seçilerek GLRaV-1’in kılıf proteini (CP), ikincil kılıf proteini (CPd2), açık okuma çerçevesi 9 (p24) ve ısı şok protein homologu 70 (HSP70h) gen bölgelerinin genetik analizleri yapılmıştır. Yapılan analizlerde, çalışılan dört gen bölgesinden CPd2 gen bölgesinin genetik çeşitliliğinin en yüksek olduğu gözlenirken en korumalı bölgenin HSP70h geni olduğu tespit edilmiştir. Gen Bankasından alınan kayıtların da kullanılması ile oluşturulan filogenetik analizler sonucunda, izolatların iki büyük grup altında kümelendiği ve Türk izolatlarının da çoğunlukla aynı grup içerisinnde kümelendiği tespit edilmiştir. Fakat, değişik coğrafik bölgelerden toplanan izolatların coğrafik bölgeye göre kümelenmediği tespit edilmiştir. Bununla birlikte, Rekombinasyon Bulma Programında (RDP) yer alan algoritmaların aracılığı ile yapılan analizlerde çeşitli rekombinasyon olayları gözlenmiştir. Sonuç olarak, elde edilen bu veriler GLRaV-1’in gerek ülkesel gerekse dünya çapında genetik varyasyon çalışmalarına katkı sağlamakta olup bağcılıkta üretim materyallerinin sanitasyon programlarının geliştirilmesine yardımcı olacağı düşünülmektedir.

Anahtar Kelimeler:

Vitis vinifera L., CP, CPd2, p24, HSP70h, genetik varyasyon

Genomic Variability and Recombination Analysis of Grapevine leafroll-associated virus-1 Isolates from Turkey

Grapevine leafroll-associated virus-1 (GLRaV-1), one of the causal agents of Grapevine leafroll disease (GLRD), is one of the most important viral diseases of grapevine worldwide. In this study, the prevalence of GLRaV-1, genetic variation and recombination events among GLRaV-1 isolates in Turkey were investigated. Initially, 197 grapevine samples from different provinces of the country were serologically tested. Of the total samples, 109 (55.32%) were identified as GLRaV-1 infected. Subsequently, 9 samples representing different geographic distribution were selected for further sequence analysis of the heat-shock protein 70 homolog (HSP70h), open reading frame 9 (p24), coat protein (CP) and coat protein duplicate 2 (CPd2). Among the four gene regions, CPd2 was found the most divergent region while HSP70h gene exhibited the lowest genetic diversity. The phylogenetic analysis of four genomic regions including GenBank records clustered all variants in two major groups and grouped Turkish isolates mostly together. However, the isolate clusters were not correlated to their geographic origin. Furthermore, several putative recombination events were detected with trace to moderate evidence support of algorithms implemented in Recombination Detection Program (RDP). Taken together, the results provide a better understanding on genetic variation of Turkish GLRaV-1 isolates in the country and worldwide and can help to improve sanitation of propagated material programs for the grape growers.

Keywords:

Vitis vinifera L., CP, CPd2, p24, HSP70h, genetic variation,

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