Invasive Species Compendium

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Abstract Full Text

First report of Rhizoctonia zeae causing stunting and root rot on wheat in Turkey.

Abstract

Rhizoctonia is a destructive soilborne pathogen with a wide host range in the world. It is one of the main causal agents of dryland root rot on wheat in Turkey. Wheat is widely planted in the Central Anatolia Region in Turkey. In order to identify species of Rhizoctonia, surveys of wheat fields in the Konya, Ankara, Eskisehir, Yozgat and Kırıkkale (provinces in the Central Anatolia Regions) were undertaken. Three of the Rhizoctonia isolates collected from necrotic lesions on the root and crown were identified as Rhizoctonia zeae (teleomorph: Waitea circinata var. zeae), as well four of the isolates from rhizosphere soils. Species identification were done according to the basis of hyphal and colony morphology, anastomosis reaction with known tester isolates and comparing sequences of Internal Transcribed Spacer (ITS) region. Colonies growth on PDA were orange when young and became salmon colored with age. Sclerotia were uniform and nearly spherical, mostly 0.2 to 0.5 mm in diameter, initially orange and turned brown during time. The number of nucleus in each hypha cell was 4 to 8. The resulting sequences were compared to other sequences and were 82 to 95% identical to other R. zeae sequences in GenBank. First pathogenicity test was conducted with agar-plate assay with all isolates and then it was tested on seedlings grown in pots the most virulent isolate on susceptible wheat cultivar. Test was done in the greenhouse conditions at 23±2°C, with a 12-h photoperiod and 50-60% RH. Average disease severity value was determined as 81%. Pathogenicity tests revealed that Rhizoctonia zeae caused significant reduction of emergence, stunting, reduction in the number of seminal roots and superficial discolouration on the hypocotyls and roots on wheat. Non-inoculated plants remained healthy. This is the first report of R. zeae isolated from wheat plants and rhizosphere soils in Turkey.