title: Sensitivity of salad greens (Lactuca sativa L. and Eruca sativa Mill.) exposed to crude extracts of toxic and non-toxic cyanobacteria.
abstract: We evaluated the effect of crude extracts of the microcystin-producing (MC+) cyanobacteria Microcystis aeruginosa on seed germination and initial development of lettuce and arugula, at concentrations between 0.5 μg.L(-1) and 100 μg.L(-1) of MC-LR equivalent, and compared it to crude extracts of the same species without the toxin (MC-). Crude extracts of the cyanobacteria with MC (+) and without MC (-) caused different effects on seed germination and initial development of the salad green seedlings, lettuce being more sensitive to both extracts when compared to arugula. Crude extracts of M. aeruginosa (MC+) caused more evident effects on seed germination and initial development of both species of salad greens than MC-. Concentrations of 75 μg.L(-1) and 100 μg.L(-1) of MC-LR equivalent induced a greater occurrence of abnormal seedlings in lettuce, due to necrosis of the radicle and shortening of this organ in normal seedlings, as well as the reduction in total chlorophyll content and increase in the activity of the antioxidant enzyme peroxidase (POD). The MC- extract caused no harmful effects to seed germination and initial development of seedlings of arugula. However, in lettuce, it caused elevation of POD enzyme activity, decrease in seed germination at concentrations of 75 μg.L(-1) (MC-75) and 100 μg.L(-1) (MC-100), and shortening of the radicle length, suggesting that other compounds present in the cyanobacteria extracts contributed to this result. Crude extracts of M. aeruginosa (MC-) may contain other compounds, besides the cyanotoxins, capable of causing inhibitory or stimulatory effects on seed germination and initial development of salad green seedlings. Arugula was more sensitive to the crude extracts of M. aeruginosa (MC+) and (MC-) and to other possible compounds produced by the cyanobacteria.
authors.affiliation: Department of Biological Sciences, Luiz de Queiroz College of Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
authors.forename: M C
authors.initials: MC
authors.lastname: Bittencourt-Oliveira
authors.affiliation: Department of Biological Sciences, Luiz de Queiroz College of Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
authors.forename: T C
authors.initials: TC
authors.lastname: Hereman
authors.affiliation: Graduating Program on Biological Sciences, Universidade Estadual Paulista "Júlio de Mesquita Filho", Rio Claro, SP, Brazil.
authors.forename: I
authors.initials: I
authors.lastname: Macedo-Silva
authors.affiliation: Department of Biological Sciences, Luiz de Queiroz College of Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
authors.forename: M K
authors.initials: MK
authors.lastname: Cordeiro-Araújo
authors.affiliation: Department of Biological Sciences, Luiz de Queiroz College of Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
authors.forename: F F C
authors.initials: FF
authors.lastname: Sasaki
authors.affiliation: Department of Exact Sciences, Luiz de Queiroz College of Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
authors.forename: C T S
authors.initials: CT
authors.lastname: Dias
mesh_terms: D019607:Brassicaceae / Q000187:drug effects* / Q000254:growth & development; D045424:Complex Mixtures / Q000633:toxicity*; D000458:Cyanobacteria / Q000737:chemistry*; D018545:Lactuca / Q000187:drug effects* / Q000254:growth & development
chemical_list: D045424:Complex Mixtures