Weeds as Potential Inoculum Reservoir for Colletotrichum nymphaeae Causing Strawberry Anthracnose in Iran and Rep-PCR Fingerprinting as Useful Marker to Differentiate C. acutatum Complex on Strawberry

Abstract

Strawberry anthracnose caused by <i>Colletotrichum</i> spp. is considered one of the most serious and destructive disease of strawberry worldwide. Weeds, as possible hosts of the pathogen, could have a role as potential inoculum reservoir. To prove this hypothesis, symptomless weeds were collected in strawberry fields showing anthracnose symptoms in Iran. Ten isolates with <i>Colletotrichum</i>-like colonies were recovered from symptomless <i>Amaranthus viridis</i> L., <i>Convolvulus arvensis</i> L., <i>Fumaria officinalis</i> L., <i>Lactuca serriola</i> L., and <i>Sonchus oleraceus</i> L. plants. The isolates were identified as <i>C. nymphaeae</i>, based on a combination of morphological and sequence data of TUB and GADPH genes. This identification was further validated using Rep-PCR fingerprinting analysis, which produces species-specific DNA fingerprints and unveils inter and intra variation of the species examined in this study. Moreover, rep-PCR marker was used to reveal accurate taxonomic position of <i>Colletorichum</i> spp. causing strawberry anthracnose belonging to the <i>C. acutatum</i> complex, including <i>C. acutatum sensu stricto, C. fiorinae, C. godetiae, C. nymphaeae, C. salicis</i>, and <i>C. simmondsii</i>. The <i>C. nymphaeae</i> isolates originating from symptomless weeds confirmed their pathogenicity on detached strawberry, proving that weeds in strawberry field may have a role as reservoir of inoculum. However, further studies are necessary to quantify their actual contribution to anthracnose epidemics in strawberry fields.