Abstract: Charcoal rot,causing by Macrophomina phaseolina (Tassi)Goid is an important soybean disease in the world.In late August 2005 and 2007,symptoms of charcoal rot-like were observed on soybean plants in one field in Tianjin and Beijing,respectively.Both fields had more than 80% disease incidence,with extensive premature death prior to pod-filling stage.Fungal isolations were made from the diseased stem tissue in order to identify the causal agent.Five resulting isolates were cultured on potato dextrose agar at 30℃,and were identified as M.phaseolina based on the gray color of the colony and the presence of microsclerotia 49.8 to 111.4 μm in size.Pathogenicity was performed by inoculation of 2-week-old seedlings of cv.Hefeng 25 using hypocotyl inoculation and cut stem techniques.All inoculated plants showed dark brown to black lesions.For each isolate tested,M.phaseolina was resolated from inoculated plants.To confirm the morphological identification,the rDNA-ITS region of the five isolates was amplified with universal primer ITS4 and ITS5.The obtained ITS sequences (one sequence GenBank accession No.FJ175382)were aligned with GenBank and showed 97%-99% similarity with isolates of M.phaseolina.PCR specific primersMpKF1 and MPKR1 for M.phaseolina were used to detect genome DNA of the five isolates,the primers produced single amplified product of 350 bp with the five isolates,and the results confirmed them as M.phaseolina.Up to now,only two notes about its occurrence were published in Liaoning Province and Shandong Province,and the causing pathogen did not have been identified.This is the first report of occurrence of charcoal rot of soybean in Northern China.

Key words: Glycine max, Charcoal rot, Macrophomina phaseolina, Identification

CLC Number: 

• S435.651