63ª Reunião Anual da SBPC

E. Ciências Agrárias - 1. Agronomia - 3. Fitossanidade

Changes in pigments promoted by Colletotrichum lindemutianum in Phaseolus vulgaris plants

Geisielly Sousa Araújo 1 Railan do Nascimento Ferreira 1 Daniele Viana da Costa 1 Talitha Soares Pereira 1 Cândido Ferreira de Oliveira Neto 1 Allan Klynger da Silva Lobato 1

1. Núcleo de Pesquisa Vegetal Básica e Aplicada - UFRA

INTRODUÇÃO:

Anthracnose is a disease promoted by the pathogen Colletotrichum lindemuthianum that attack Phaseolus vulgaris plants. This fungus under favorable conditions as high temperature and humidity can infect common bean crop in all growth stages. In addition, this pathogen causes morphological, physiological and biochemical alterations that has been previously described in Phaseolus vulgaris, such as the significant decrease in photosynthetic pigments. The objective of this study was to evaluate infection effects promoted by Colletotrichum lindemutianum pathogen (race 2047) on leaf pigments in Phaseolus vulgaris plants (cv. Mexico 222).

METODOLOGIA:

The study was conducted in greenhouse and growth chamber conditions located in Núcleo de Pesquisa Aplicada à Agricultura (Nupagri) that is situated in Research Station of the Universidade Estadual de Maringá (UEM). Seeds of Phaseolus vulgaris Mexico 222 cultivar, which presents a determined growth, it was obtained from the Nupagri seed bank. Pathogen employed to infect the plants was the fungus Colletotrichum lindemuthianum race 2047, and cultivar Mexico 222 was to this fungus. Chlorophyll a and b was determined using 25 mg of leaf tissue taken from first trifoliate leaf that presented progressive infection symptoms during 4, 8 and 12th day after the pathogen inoculation. Tissue samples were homogenized in dark with 2 mL of acetone 80% (Nuclear) and centrifuged at 5.000 g, for 10 minutes at 5ºC. Chlorophyll a and b, carotenoids and total chlorophyll were quantified using spectrophotometer in the supernatant phase.Data were analyzed employing a variance analysis, and using Tukey test at 5% level of probability. Standard errors were also calculated in all treatments evaluated.

RESULTADOS:

The chlorophyll a/b ratio presented significant differences only at the 12th day after pathogen inoculation showing a significant reduction in the chlorophyll a/b ratio, if compared with the 8th day Similarly, carotenoids contents was altered by the pathogen presence, which showed significant reductions at the in 8 and 12th day after the pathogen inoculation. Total chlorophyll level also was modified (significant differences) at the 8 and 12th day after infection. Inoculated plants a decreases of 6.4, 20.6 and 21.3% at the 4, 8 and 12th respectively, when they are compared with the control plants. A reduction on the chlorophyll a/b ratio on infected plants by the fungical pathogen occurred mainly by minor chlorophyll a content. Carotenoids level presented significant reductions in 8 and 12th day as consequence of the infection expansion and consequent cell death produced by the pathogen in leaf tissue. Total chlorophyll amount in inoculated plants presented significant decrease by two factors, means as less leaf photosynthetic area, less light absorption, and chloroplast disorders during the pathogen.

CONCLUSÃO:

Study reveals that infection by Colletotrichum lindemuthianum causes significant changes in chlorophylls and carotenoids.

Palavras-chave: chlorophylls, carotenoids, common bean.