Russian Isolates of Potato spindle tuber viroid Exhibit Low Sequence Diversity.

Potato spindle tuber viroid (PSTVd) is currently widespread in seed potatoes grown in Russia. Characterization of 39 PSTVd isolates collected over a 15-year period from widely separated areas in Russia revealed the presence of 17 different sequence variants, all but one of which were previously unknown. Most variants were recovered only once, but two were more widely distributed; one of these was a mild variant previously isolated in Germany, the second was a novel variant inducing symptoms similar to those of the type strain in tomato.

Identification of phytoplasma species associated with potato diseases in Russia.

Four out of six known potato diseases attributed to phytoplasma infection were previously reported to occur in Russia based on a combination of biological properties such as symptomatology and/or vector relationships and electron microscopy of infected phloem tissue. In 2007, the first molecular identification of potato diseases causing symptoms including purple top, round leaves, stunting, bud proliferation and formation of aerial tubers was carried out using PCR methods. A nested PCR using primer pair P1/P7 in the first amplification followed by R16F2n/R16R2n in the second amplification was performed to detect phytoplasma in infected potato samples.

Russian isolates of potato spindle tuber viroid.

Forty PSTVd isolates collected from five regions of Russia (North-western, Central, Volga region, Northern Caucasus and the Far East) were sequenced during 2006-2008. All isolates lacked the adenine residue present at position 123 of the type strain; i.e.

Molecular Detection and Identification of Group 16SrI and 16SrXII Phytoplasmas Associated with Diseased Potatoes in Russia.

Phytoplasmal diseases have long been suspected to occur in several potato-growing regions in Russia on the basis of symptoms and the presence of insect vectors. Symptoms resembling stolbur are most prevalent, but round leaf disease, potato witches'-broom, and potato purple top wilt also occur (1). The phytoplasma etiologies of these diseases have never been verified by molecular means.

Recovery of Four Novel Potato spindle tuber viroid Sequence Variants from Russian Seed Potatoes.

First described in the early 1930s, the limited distribution of potato "gothic" disease made it of little economic significance in European Russia until the early 1970s when meristem-tip culture was widely adopted throughout the former USSR to increase production of virus-free seed potatoes. Shortly thereafter, the yield and quality of Russian seed potatoes began a dramatic decline. Symptoms of potato "gothic" resemble those of Potato spindle tuber viroid (PSTVd) (3), and initial suspicions that in vitro plantlets and seed potatoes might be viroid-infected were later proved correct when Kastalyeva et al.