Cultural characteristics and aggressiveness of isolates of Alternaria solani from potato and tomato / Características culturais e agressividade de isolados de Alternaria solani de batateira e tomateiro

AUTOR(ES)

Christiana de Fátima Bruce da Silva

DATA DE PUBLICAÇÃO

2006

RESUMO

Several experiments were conducted both under laboratory and greenhouse conditions to quantify putative differences between isolates of A. solani obtained from potato and tomato plants. Morphophysiological attributes and aggressiveness components were assessed. The following morphophysiological variables were measured: septation, length, width, shape, and color of conidia; length and number of beaks; colony texture and color; and mycelial growth. There were no significant differences between potato and tomato isolates for any of the morphophysiological variables included in this study. Conidia of isolates from both potato and tomato were dark-brown and long-cone shaped. Colony texture was in general cottony, and aerial mycelium was reddish-yellow (2.5 Y and 10 YR) or, predominantly, greenishyellow (7.5Y) in color. Lack of pigmentation was more frequently observed for isolates obtained from tomato. There was variation regarding mycelial growth. In both trials, values of the area under the growth curve for the isolates from potato were smaller than those for tomato. There was no difference between conidia germination for tomato and potato isolates. In one of the two trials, the in vitro production of conidia for the potato isolates was smaller than that obtained for the tomato isolates; however, in general, no significant differences were detected. No differences regarding aggressiveness, estimated by the epidemiological components: infection frequency, incubation and latent periods, and lesion size were detected between potato and tomato isolates. There was no evidence of host-specific populations of A. solani. Morphological, physiological and pathogenic data on variables obtained from this study suggest that there is a homogeneous species of Alternaria in Brazil: A. solani, causing early blight in the two hosts.

ASSUNTO(S)

physiology fitopatologia solanum tuberosum lycopersicon esculentum solanum tuberosum pinta-preta lycopersicon esculentum solanum lycopersicon alternaria solani fisiologia solanum lycopersicon plant pathogenic fungi early blight fungos fitopatogênicos alternaria solani

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