63ª Reunião Anual da SBPC
E. Ciências Agrárias - 1. Agronomia - 4. Fitotecnia
Interference on chlorophylls a and b of common bean produced by Colletotrichum lindemuthianum
Raquel Passabom Lemos 1
Argemiro Pereira Martins Filho 1
Eldenira Barbosa Uchôa 1
Railan do Nascimento Ferreira 1
Izabelle Pereira Andrade 1
Allan Klynger da Silva Lobato 1
1. Núcleo de Pesquisa Vegetal Básica e Aplicada, Univesidade Federal Rural da Amazônia
INTRODUÇÃO:
Photosynthetic pigments in plants are comprised by chlorophylls a and b, and these pigments are responsible mainly by capture light in the antenna complex via photosystem II, with consequent electron transport. Investigating Phaseolus vulgaris plants exposed to pathogen infection described significant pigment loss. Recent study carried by reveals a negative effect of Colletotrichum lindemuthianum pathogen (race 2047) on leaf pigments in Phaseolus vulgaris plants (Mexico 222), which caused significant reductions in carotenoids and chlorophyll. Aim of this study was to investigate impact on chlorophylls a and b in Phaseolus vulgaris leaf induced by two Colletotrichum lindemuthianum races, which promote resistance and susceptibility in Mexico 222 cultivar.
METODOLOGIA:
The study was conducted in greenhouse and growth chamber conditions located in Núcleo de Pesquisa Aplicada à Agricultura (Nupagri), 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 races 7 and 2047, where Mexico 222 is resistant and susceptible to races 7 and 2047, respectively. Plants were grown in greenhouse conditions controlled by the local weather minimum/maximum temperature was 34.8/13.5ºC and relative humidity was 55/81%, respectively, during the experimental period. Inoculum obtained from Nupagri was transferred culture tubes that contained growing medium and immature pod beans. Experimental design employed was completely randomized with 3 treatments (control, resistant and susceptible). The experiment was composed of six replicates, and thirty six experimental units (1 plant in each unit). In this study were evaluated chlorophylls a and b in 8th after inoculation, being measured in well expanded trifoliolate leaves 3rd, located at the middle of the main branch at the stage V4. Pigments were quantified according to Lichthenthaler (1987). Data were analyzed employing a variance analysis, and using Scott-Knott test at 5% level of probability. Standard errors were also calculated in all treatments evaluated.
RESULTADOS:
Chlorophyll a levels showed in control, resistant, and susceptible treatments were 3.64, 3.37, and 2.90 mg g FM-1, respectively, and statistically control and resistant treatments were similar, despite reduction promoted by pathogen contact with leaf superficies. Fall significant not in resistant treatment can be explained due to resistance activation process, occurring accumulation of reactive oxygen species (ROS) that cause oxidation of pre-existing pigments in chloroplasts. Similar results with reported in this study were described by studying interaction between Mexico 222 x race 23, where this cultivar is resistant also to this race, showing not significant alterations of chlorophylls a. In relation to chlorophyll b were obtained 3.31, 3.08, and 2.83 mg g FM-1 in control, resistant, and susceptible treatments, respectively. In addition, significant reduction was showed only in susceptible treatment. Reductions in chlorophylls a and b showed in susceptible treatment probably will have consequence in carbon metabolism, because damage in chloroplast structures promoted by C. lindemuthianum pathogen reduces capacity of light absorption carried by these pigments, and this energy is fundamental during process of carbon fixation.
CONCLUSÃO:
This investigation proves that plant-pathogen interaction in common bean presents significant interference on photosynthetic pigments in susceptible, and significant not in resistant plants.
Palavras-chave: pathogen, Phaseolus vulgaris, chlorophylls.