Interferência de ulvana no desenvolvimento e melanização de apressórios de Colletotrichum gloeosporioides

Abstract

RESUMOO polissacarídeo algal ulvana induz resistência em macieira à mancha foliar de Glomerella. Porém, modificações no processo pré-infeccioso de Colletotrichum gloeosporioides vêm sendo relatadas em plantas previamente tratadas com ulvana. Assim, este trabalho objetivou verificar se o polissacarídeo interfere diretamente no desenvolvimento de estruturas pré-infectivas. Para tanto, depositou-se gotas de 10 µL de suspensão de 2x10 5 conídios.mL -1 em segmentos de papel celofane, assentados sobre lâminas de vidro. A suspensão conidial foi preparada com solução aquosa contendo ou não ulvana (10 mg.mL -1 ). As amostras foram incubadas a 25°C e 100% de humidade relativa. A cada duas horas, 100 conídios por gota foram examinados microscopicamente (200x), por um período de 16h. As taxas de germinação de conídios, formação e melanização de apressórios foram quantificadas. A germinação dos conídios não foi afetada. Ulvana estimulou o alongamento do tubo germinativo, mas retardou a diferenciação do primeiro apressório (séssil). O polissacarídeo acelerou a formação do segundo apressório, mas inibiu a sua melanização. Palavras-chave: Ulva fasciata, apressório, germinação, macieira, melanina, polissacarídeo. ABSTRACT Interference of ulvan on apressoria development and melanization of Colletotrichum gloeosporioidesThe algal polysaccharide ulvan induces resistance in apple to Glomerella leaf spot. However, changes in the pre-infectious process of Colletotrichum gloeosporioides have been reported in apple plants previously treated with ulvan. Thus, this study aimed to verify if the polysaccharide interferes directly in the development of pre-infective structures. For this, 10 µL drops of spore suspension (2x10 5 conidia.m L -1 ) were distributed on cellophane paper segments settled on glass slides. The conidial suspension was prepared with aqueous solution with (10 mg.mL -1 ) or without ulvan. Samples were incubated at 25°C and 100% relative humidity. At every two hours of incubation and over a period of 16 hours, 100 conidia per drop were microscopically (200x) examined. The rates of conidia germination, apressoria formation and melanization were quantified. Germination of conidia was not affected. Ulvan stimulated the elongation of the germ tube but retarded the differentiation of the first apressorium (sessile). The polysaccharide accelerated the formation of second apressorium, but inhibited its melanization.

Association of the Production of Phenylpropanoid Compounds at the Infection Sites of Corynespora cassiicola with Soybean Resistance against Target Spot

“…The appressorium is a primordial infection structure formed by some plant pathogens to penetrate their host tissue in an efficient way (Dean ; Araujo and Stadnik ; Gonçalves and Stadnik ; Araujo et al. ).…”

“…The appressorium is a primordial infection structure formed by some plant pathogens to penetrate their host tissue in an efficient way (Dean 1997;Araujo and Stadnik 2011;Gonc ßalves and Stadnik 2012;Araujo et al 2014c). An appressorium-like structure was formed by C. cassiicola at one or both extremities of the conidium, and preferentially at the major and minor veins on the adaxial leaf surface of plants from both cultivars.…”

“…An appressorium-like structure was formed by C. cassiicola at one or both extremities of the conidium, and preferentially at the major and minor veins on the adaxial leaf surface of plants from both cultivars. Some pathogens are able to form a second appressorium in case the first one fails to penetrate the host tissue; however, not all conidia have sufficient energy to invest in this event (Dean 1997;Araujo and Stadnik 2011;Gonc ßalves and Stadnik 2012;Araujo et al 2014c). In the present study, the formation of two appressoria-like structures per conidium of C. cassiicola indicated that it had sufficient energy to produce them.…”

Investigating variability and behaviour of Colletotrichum gloeosporioides strains from lesions of coffee blister spot

“…Ten strains showed the highest percentage of CATs, ranging from 7% (UFLA 43) to 16% (UFLA 39). The presence of CATs in species of Colletotrichum genus has been reported in common bean (Barcelos et al, ; Mota et al, ; Pinto et al, ) and apple (Araújo & Stadnik, ; Gonçalves & Stadnik, ).…”

“…(UFLA 39). The presence of CATs in species of Colletotrichum genus has been reported in common bean (Barcelos et al, 2014;Mota et al, 2016;Pinto et al, 2012) and apple (Araújo & Stadnik, 2013;Gonçalves & Stadnik, 2012).…”