Isolation and Identification of Phomopsis vexans Harter and Optimization of Sporulation Conditions

【Objective】Phomopsis blight of eggplant caused by Phomopsis vexans Harter is an important disease in the current eggplant industry. A sufficient amount of spores is the material basis for studying the spore germination of P. vexans and its pathogenic mechanism. This research is aimed to further simplify the current complex sporulation process and improve the sporulation efficiency.【Method】The tissue separation method was used to isolate and purify the pathogen. The morphological characteristics observation and rDNA-ITS sequence analysis were used to identify the pathogen. The liquid culture method was used to optimize the sporulation conditions of P. vexans.【Result】The rDNA-ITS sequence of P. vexans was obtained. The sequence had the closest genetic relationship with P. vexans through NCBI and sequence alignment, with a homology of 99%. After cultivation for one day under the same condition, the mycelial growth in the liquid medium was better. The spore production after culture at 28 ℃ for one day then 24 ℃ for three days was 1.2 × 1010 spores/mL, which was larger than the spore production（6 × 107 spores/mL）after culture at 24 ℃ for four days. The spore production at different culture temperatures were 2.5×107（20 ℃）, 1.2×1010（22 ℃）, 9.4×109（24 ℃）and 8.5×108（26 ℃）spores/mL, respectively. Under the same culture condition, the 25% glucose PDB medium had the highest spore production（1.2×1010 spores/mL）.【Conclusion】The pathogens of P. vexans were isolated and identified, and the sporulation conditions were optimized. The optimized sporulation conditions were as follows: in a 150 r/min shaker, using the 25% glucose PDB medium to culture at 28 ℃ for one day, and then culture at 24 ℃ for three days.