Morpho-molecular identification of Fusarium oxysporum as the causal agent of dry rot of carrot in Pakistan

Abstract

Fusarium  rot or dry rot  is an emerging threat to carrot field, which is responsible for significant economic losses worldwide. The objective of this study was to identify Fusarium species associated with  dry rot of carrot (Daucus carota).For this porpuse, ten isolates of Fusarium sp. were collected from symptomatic carrot roots at Vegetable Research Station Sahiwal (VRSS). During morphological studies, fungal colonies were observed whitish, cottony with abundunt arial mycelium. In microscopic observations, macroconidia was falciform and measured 12.1 to 30.7 (L) × 3.6 to 5.8 (W) μm with 2 to 3 septations, while elliptic microconidia of 5.8 to 8.6 (L) × 2.9 to 3.6 (W) μm with none or one septate. For molecular characterization, three isolates (ON955520, ON955053 & ON955054) were amplified using ITS1 & ITS4 primers. Sequence comparison revealed 99-100% genetic homology with previously reported isolates of F.oxysporum. To our knowledge, the occurrence of fusarium rot caused by F.oxysporum on carrot field is the first time reported in Pakistan which can cause reduction in crop yield.