The Biological Characterization And Molecular Phylogenetic Analyses Of Penicillium Spp. That Causing The Mold Fruit Of Citrus

Penicillium spp. was the most important fungus causing the citrus fruit to decay.34 isolates were collected from citrus fruit with typical blue and green mould symptoms in the major citrus production area of China; Utilization of the colony characteristics on different media and their molecular identification, identify and classify each isolates into species; Examination of the pathogenicity of these isolates on citrus fruit, and the infection process was also observed by using sanning electron microscope (SEM) and paraffin section; Analysis of the sensitivity of all these isolates to the fungicide-Prochloraz; Evaluation of the phylogenetic diversity among these isolates based on the sequences of ITS, CO1 and BenA gene. The main results were as below:1. Based on one gene, the correct identification of these isolates can not be gained. By using the sequences of ITS, BenA and CO1 gene, and combining the traditional morphological taxonomic method, these isolates were classified into five species.2. P. digitatum and P. italicum had the highest pathogenicity, and there had no lesion in citrus fruit inoculated with P. chrysogenum. P. crustosum and P. polonicum had the intermediate pathogenicity between them. The pathogenicity of these five species on the satsuma mandarin was consistent with valencia orange.3. Prochloraz was highly effective against P. italicum, P. digitatum and P. polonicum, the EC50 of which was less than 3μg/ml. However, for the most isolates belonged to P. crustosum, they had a high Prochloraz-resistance.4. Scanning electron microscopy showed the fruit surface was adhered with artificially inoculated spores of Penicillium spp. The mycelium grow profusely at the wound sites. The technology of paraffin sections was also used to observe the process of the infection. It was found that the degeneration of the albedo occurred earlier than the out yellow.5. These 34 isolates were selected for further molecular phylogenetic analysis based on the sequences of ITS, BenA and CO1 gene. Although the phylogenetic trees were structed well, respectively. In this study, the relationship among the Penicillium species was different from one gene to other.