PATHOGENIC AND MOLECULAR VARIABILITY OF PUCCINIA HORIANA Henn. ISOLATES

Abstract

The pathogenic and molecular variability of 16 isolates of Puccinia horiana collected from the States of México, Morelos and Puebla were studied. Five chrysanthemum Dendranthema grandiflara Tzveler cultivars (‘Indianápolis’, ‘Harman’, ‘Eleonora’, ‘Vikyngo’ y ‘Marble’) were inoculated with the isolates. The isolates from the State of México were the most virulent as compared to those collected from Morelos and Puebla, since the incubation period in ‘Indianapolis’ took around 15 d whereas the isolates from Morelos and Puebla required 3 and 4 more d. For the isolates from the State of México the maximum incidence in ‘Indianápolis’ was reached only 4 d after the first symptoms appeared, whereas those from Morelos and Puebla needed 5 and 6 more d. Of the isolates coming from the State of México, 539 to 977 basidiospores were trapped in 0.25 cm² ; in contrast, for those from Morelos and Puebla only 76 and 42 basidiospores were trapped. In the isolates from the State of México the severity fluctuated from 23 to 36 %, whereas in those coming from Morelos and Puebla varied from 5.7 to 8.5 % and from 4.2 to 7.3 %. Through the DNA polymorphism
analyses with RAPD, MP-PCR and RAMP, three groups were identified (a, b y c) which corresponded exactly to the geographical origin of the isolates.