Molecular characterization and pathogenicity of cylindrocarpon destructans isolates from grapevines in Duhok, north Iraq

الملخص EN

Ten Cylindrocarpon isolates were detected from roots of declined grapevines (Vitis vinifera L.) plants collected from five vineyards in Duhok governorate, North Iraq.

The symptoms of the declined host including reduce vigor with small-sized trunks ,reduction in root biomass, black discoloration and brown to black streaks in wood mainly at the base of rootstock .Based on cultural and morphological characteristics, all isolates were identified as C.destrunctans.

These isolates were subjected to species-specific PCR assay.

Total genomic DNA was isolated from pure cultures of the isolates.

The average DNA yields ranged between 1.5-6.7 μg / ml with a purity 1.6-1.8.

The specific primers for C.

destructans (400 bp) were used to amplify the ITS region of nuclear ribosomal DNA (rDNA) containing ITS1, ITS2 and the intervening 5.8 rRNA genes of Cylindrocaropon produced appropriate and successful results with the selected isolates confirmed that all isolates were correctly identified as C.

destructans.

Pathogenicity of C.

destructans was tested under greenhouse conditions.

One-year old dormant rooted cuttings of the two grape cultivars, Reshmew and Taefi, were inoculated by dipping their roots for 30 min in the conidial suspension (1 × 106 conidia ml-1).

Infected vines showed reduced vigour with small leaves, interveinal chlorosis and necrosis.

Other symptoms included a reduction in root biomass and root hairs.

The severity of root mass reduction reached to 0.41 on Taefi (cv.) after five months of inoculation with significant difference compared with control treatment.

C.

destructans caused significant decrease in the fresh and dry weight of grapevine shoots and roots.

This fungus is reported for the first time in Iraq during this study.