Variation in pathogenicity, morphology, and RAPD marker profiles in Colletotrichum graminicola from turfgrasses

Anthracnose basal rot (ABR), caused by Colletotrichum graminicola (Ces.) Wils., is a destructive disease of annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis palustris Huds.) golf course putting greens in North America and western Europe. Typically, only one of these turfgrass species is affected by ABR when both are present in putting greens. The objectives of this study were to determine if isolates of C. graminicola from annual bluegrass and creeping bentgrass are host specific and if differences in pathogenicity, morphology, and randomly amplified polymorphic DNA (RAPD) marker profiles occur amoug isolates from annual bluegrass, creeping bentgrass, and corn (Zea mays L.). One isolate of C. sublineolum P. Henn. apud Kabat and Bub. from sorghum [Sorghum bicolor (L.) Moench] was included for comparison in morphology and RAPD marker studies. Pathogenicity studies using C. graminicola isolates were conducted in growth chambers on annual bluegrass and creeping bentgrass. Although several isolates were more virulent on the host species from which they were isolated, strict host specificity was not observed. No consistent differences in conidia length were found between annual bluegrass isolates and those from creeping bentgrass. However, differences in conidia length were found between corn isolates and isolates from turfgrasses and sorghum. Cluster analyses of RAPD markers showed that isolates from annual bluegrass and creeping bentgrass separated into two distinct groups. Analysis of molecular variance (AMOVA) revealed that significant genetic differences (P = 0.001) exist between isolates obtained from annual bluegrass and isolates from creeping bentgrass.