Isolation and identification of pathogenic fungi causing sorghum anthracnose in Heilongjiang province

Abstract:

[Background] Sorghum anthracnose in Heilongjiang province is one of the main sorghum diseases, which seriously affects the yield and quality of sorghum. [Objective] To definitize the pathogen species of sorghum anthracnose in Heilongjiang province. [Methods] The pure culture of pathogenic fungi causing sorghum anthracnose was obtained by tissue separation and single spore purification. The isolated pathogenic fungi were confirmed by Koch’s rule. The morphological characteristics of colony, sporulation structure, morphology and size of conidia, were used to identify the pathogen combined with rDNA ITS sequence characteristics. [Results] Three isolates D13, H4 and Z24 isolated from different regions were pathogenic fungi of sorghum anthracnose by Koch’s rule. Morphological observation showed that the colony growth rate of 3 strains on PDA medium (28 °C) was 7.3?12.3 mm/d, the hyphae was white, grayish white to grayish brown, and the colony was light yellow to orange. Setae erected and its base distended, were brown or dark brown, with 3?5 grids. Conidiophore generates directly from hypha, colorless and eseptate, short, erected or slightly curved, unbranched. Conidia are unicellular, sickle, acuminate to both ends, smooth, colorless, sometimes with an oil ball. The appressorium produced from the apex of the hyphae or mycelium, the apex is dilated, with color of brown or dark brown, subglobose, ovoid, elliptic or spindle-shaped and its margin was smooth, lobes, more lobes or deep lobes. The rDNA ITS sequence accession numbers obtained from isolated D13, H4 and Z24 were MW040055, MW040057 and MW040056, respectively. The phylogenetic tree based on rDNA ITS sequence found that the D13, H4 and Z24 of the isolates were together with Colletotrichum sublineola. [Conclusion] The pathogen causing sorghum anthracnose in Heilongjiang province is C. sublineola.

Key words:sorghum, anthracnose, pathogenic fungi identification, Colletotrichum sublineola