IDENTIFICACIÓN MOLECULAR DE GRUPOS ANASTOMÓSICOS DE Rhizoctonia solani ASOCIADOS A LA COSTRA NEGRA Y CANCRO DEL TALLO EN EL CULTIVO DE PAPA EN SINALOA

Abstract

The potato is the fourth most important food in the world. In Mexico, this is very important crop and is grown almost everywhere in the country, being Sinaloa among the states with the highest production. Black scurf and stem canker diseases caused by the fungus Rhizoctonia solani affects potato cultivation worldwide, decreasing tuber quality and causing yield losses up to 30%. R. solani has divided into anastomosis groups (AGs), in which isolates are categorized according to the ability of their hyphae to anastomose (fuse) with another. The AGs AG1, AG2, AG3, AG4, AG5 and AG7 have been associated with black scurf disease of potato, causing necrosis of shoots, stem canker, strangulation of stolons, tubers deformation, and formation of sclerotia on them, being the most common and aggressive AG3 and AG4. The aim of this study was the molecular identification of anastomosis groups of R. solani associated to black scurf and stem canker of potato in Sinaloa crops. Symptomatic plants and tubers were collected from potato crops in Sinaloa. The isolates obtained from R. solani were maintained on PDA medium. Molecular identification of AGs was made by PCR using ITS1/ITS4 primers and AG1, AG2 and AG3 group specific primers, sequencing of amplified PCR fragments and new AG4 designed primers. PCR fragment sequences of 27 putative Rhizoctonia isolates allowed us to identify Rhizoctonia binucleate (two isolates), R. solani AG4 (five isolates) y R. solani AG3 (18 isolates). Specific PCR primers for AG3 and AG4 showed low specificity for the amplification of the isolates from this study