Morpho-molecular variability of different isolates of Ustilagonoidea virens causing false smut of rice

Abstract Spore balls of false smut of rice caused by Ustilagonoidea virens were collected from different major rice belts of eastern part of India. Ten isolates from ten different locations were collected and isolated in the laboratory for their, cultural, morphological and molecular characterization. Potato sucrose agar media was used for their cultural studies and observation on colony diameter, colour and sporulation were made. Spores of all the isolates were observed under scanning electron microscope (SEM) and light microscope for spore size, spine length and colour. Differences in colony characters were observed where the highest mycelial growth was observed in isolate Uv2 with 5.33 cm colony diameter and lowest mycelial growth was observed in Uv9 (3.70 cm). Most of the isolates produced white and circular colony. Spores of all the isolates observed under a light microscope appeared to be olive green in colour, however, a significant variation in spore size and spike length under SEM was observed. Spores size and spike length of different isolates ranged between 4.533 μm to 6.169 μm and 362.567 nm to 799.533 nm, respectively. For genetic identification and variability, DNAs of isolates were amplified using ITS1 and ITS 4 primers. The length of nucleotide sequences of different isolates varied from 583 to 606 bp. Phylogenetic analysis revealed genetic variation among the isolates, dividing them into two major groups.