Relação entre a estrutura foliar de feijoeiro e a pré-infecção por Glomerella cingulata f.sp. phaseoli

Abstract

Resumo -Os objetivos deste trabalho foram mensurar a área da nervura secundária e quantificar o número de tricomas da superfície foliar de cultivares de feijoeiro suscetível (Carioca), moderadamente resistente (Pérola) e resistente (IAPAR-81) à antracnose, e observar as relações entre tais características com o estágio pré-infeccional. Para mensurar a área da nervura secundária, fragmentos foliares foram amostrados, fixados em FAA 50, conservados em álcool 70%, infiltrados em resina glicol-metacrilato, cortados transversalmente e corados com azul de toluidina. Os tricomas foram quantificados em impressões epidérmicas em microscópio de projeção. Na análise pré-infeccional, o material foi fixado em glutaraldeído 2,5% e processado para o estudo ao microscópio eletrônico de varredura. A cultivar resistente apresentou menor área de nervura secundária e maior pilosidade que a cultivar moderadamente resistente e a suscetível. Na cultivar resistente, por causa da menor área de nervura e maior pilosidade, o patógeno permaneceu sobre a nervura e envolvido com o tricoma. Na cultivar suscetível, com maior área de nervura e menor pilosidade, foram observadas necrose e estruturas fúngicas na superfície foliar. Há relação entre estas características foliares e a resistência à antracnose durante o estágio pré-infeccional do patógeno.Termos para indexação: Phaseolus vulgaris, antracnose do feijoeiro, superfície foliar, tigmotropismo, tricomas. Relationship between bean leaf structure and the Glomerella cingulata f.sp. phaseoli preinfectionAbstract -The objectives of this work were to measure the secondary vein area and to quantify the trichomes of leaf surface in bean cultivar susceptible (Carioca), medium resistant (Pérola) and resistant (IAPAR-81) to anthracnose, and to observe relationships between leaf blade characteristics with the preinfectional stages. In order to measure the secondary vein area, sample leaf pieces were fixed in FAA 50 and conserved in 70% alcohol. These leaf samples were infiltrated in glycol metacrylate resin, cut transversally and stained with toluidine blue. The trichomes were quantified in epidermical impressions in projection microscopy. The material for preinfection analysis was fixed in 2.5% glutaraldehyde and processed to study the scanning electron microscopy. The resistant cultivar showed minor secondary vein area and high pilosity than the cultivar medium resistant and susceptible. In the resistant cultivar, due to minor vein area and high pilosity, the pathogen stayed on the vein and involved on the trichomes. In susceptible cultivar, with high vein and minor pilosity, necrosis and fungal structure on the leaf surface were observed. The results show a relation between the minor vein and high leaf trichomes quantity with the resistance to the anthracnose in pathogen preinfection stages.

Histochemical Screening of Leaves Compared to in situ and in vitro Calluses of Solanum aculeatissimum Jacq.

“…The plants' morphology can help in the identification of the microbe's family, and their functions are dependent on their type and location (Munien et al, 2015). The presence of trichomes in in situ leaves may be related to protection, and the following 2 factors are considered: the presence of substances derived from the secondary metabolism in secretory glands and the number of trichomes present (Jerba et al, 2005).…”

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

“…The level of resistance of bean cultivars to anthracnose was associated with a high trichome density (Jerba et al. ). Trichomes on the leaves of chickpea plants can secrete acidic fluid that inhibits the germination of conidia of Ascochyta rabiei (Armstrong‐Cho and Gossen ).…”

“…On the leaf sheaths of rice plants from a resistant cultivar, the hyphae of Rhizoctonia solani grew less abundantly; consequently, the sheath blight symptoms were reduced (Marshall and Rush 1980;Schurt et al 2015). The level of resistance of bean cultivars to anthracnose was associated with a high trichome density (Jerba et al 2005). Trichomes on the leaves of chickpea plants can secrete acidic fluid that inhibits the germination of conidia of Ascochyta rabiei (Armstrong-Cho and Gossen 2005).…”

Microscopia eletrônica de varredura do processo infeccioso de Ramularia areola em folhas de algodoeiro

“…A esporulação de R. areola ocorreu com os conidióforos emergindo agrupados através dos estômatos (Figuras 2a-b colonizam preferencialmente as nervuras das folhas são mais agressivos, pois, em contato direto com os vasos do xilema carreando seiva bruta, podem disseminar suas estruturas reprodutivas, além de toxinas, de forma mais rápida e eficiente a exemplo de Colletotrichum lindemuthianum em feijoeiro (Jerba et al, 2005). No caso do algodoeiro, é raro observar estômatos sob as nervuras.…”