Liquid shake culture overcomes solid plate culture in inducing conidial production of Colletotrichum isolates

Abstract

Species of fungi in the genus Colletotrichum cause damaging anthracnose diseases on many economically important fruit, vegetable, and ornamental crops. Unfortunately, the fact that many isolates fail to sporulate on artificial media limits research requiring conidia. We found that liquid culture efficiently rescued conidial production of Colletotrichum isolates being impotent to do so on solid plate media, with the yield averaging 107 per mL after four days. We determined that the most efficient culture protocol was potato dextrose broth (PDB) shake culture (140 rpm) at 25 °C. In addition, it was essential that enough medium was used to cover the mycelial balls. The method was applicable to different Colletotrichum species from a range of hosts. In sum, we report here that liquid shake culture offers an alternative in inducing conidia production of ‘non-sporulating’ Colletotrichum isolates, a critical step for many research activities in the lab.