Identification of Pyricularia Species Isolated from Rice and Grasses using Morphological Characteristics and Pot2 rep–PCR

Abstract

Forty-two strains of Pyricularia were isolated from rice and grasses collected from selected areas in 16 provinces of Thailand. Fungal identification was studied on the basic of the conidial characteristics and host plant varieties. The conidial sizes of the fungal pathogens derived from rice (20.89 – 28.14 × 7.39 – 10.50 μm) are larger than those of all isolates derived from grasses (18.12 – 24.93 × 5.27 – 9.77 μm). In addition, conidial average sizes of isolates derived from neck blast (20.89 – 28.14 x 7.60 –10.50 μm) are larger than those of the isolates isolated from leave (18.12 – 26.51 × 5.27 – 9.77 μm). Differentiations on the basis of the conidial shape were divided into six groups, but the shape, length and width of conidia are slightly different from those groups, resulting to morphologically unsuccessful identification. Molecular data for genetic relationships using the Pot2 rep–PCR technique revealed that five isolates of Pyricularia grisea were discovered from grasses, whereas thirty-seven isolates of P. oryzae were found from both grasses and rice. Additionally, the genetic characteristics of the fungal isolates have partially similar sequences that are highly similar among isolates. Due to the high genetic diversity of Pyricularia species, the data showed that the conidial characters and molecular genetic evidence are incongruent.