RESUMO
Phloem-feeding aphids cause serious damage to plants. The mechanisms of plant-aphid interactions are only partially understood and involve multiple pathways, including phytohormones. In order to investigate whether salicylic acid (SA) is involved and how it plays a part in the defense response to the aphid Macrosiphoniella sanbourni, physiological changes and gene expression profiles in response to aphid inoculation with or without SA pretreatment were compared between the aphid-resistant Artemisia vulgaris 'Variegata' and the susceptible chrysanthemum, Dendranthema nankingense. Changes in levels of reactive oxygen species, malondialdehyde (MDA), and flavonoids, and in the expression of genes involved in flavonoid biosynthesis, including PAL (phenylalanine ammonia-lyase), CHS (chalcone synthase), CHI (chalcone isomerase), F3H (flavanone 3-hydroxylase), F3'H (flavanone 3'-hydroxylase), and DFR (dihydroflavonol reductase), were investigated. Levels of hydrogen peroxide, superoxide anions, MDA, and flavonoids, and their related gene expression, increased after aphid infestation and SA pretreatment followed by aphid infestation; the aphid-resistant A. vulgaris exhibited a more rapid response than the aphid-susceptible D. nankingense to SA treatment and aphid infestation. Taken together, our results suggest that SA could be used to increase aphid resistance in the chrysanthemum.
Assuntos
Afídeos/fisiologia , Artemisia/efeitos dos fármacos , Chrysanthemum/efeitos dos fármacos , Proteínas de Plantas/genética , Ácido Salicílico/farmacologia , Aciltransferases/genética , Aciltransferases/metabolismo , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Animais , Afídeos/patogenicidade , Artemisia/genética , Artemisia/metabolismo , Artemisia/parasitologia , Chrysanthemum/genética , Chrysanthemum/metabolismo , Chrysanthemum/parasitologia , Comportamento Alimentar/fisiologia , Flavonoides/biossíntese , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Parasita , Liases Intramoleculares/genética , Liases Intramoleculares/metabolismo , Malondialdeído/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Fenilalanina Amônia-Liase/genética , Fenilalanina Amônia-Liase/metabolismo , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Especificidade da EspécieRESUMO
Many angiotensin converting enzyme inhibitory peptides (ACEIP) have been identified in recent years. Among all the literatures available thus far, almost all the ACEIP were obtained by means of enzymatic hydrolysis. However, little information was available on antihypertensive peptides obtained by DNA recombination technology. In the present paper, our aims were 1) to establish a new method to produce antihypertensive peptides (AHP), and 2) to study the expression profiles of different host strains (Escherichia coli JM109 and DH5alpha). To achieve these objectives, a DNA fragment encoding the published ACEIP, identified as FFVAPFPEVFGK (known as CEI12) was synthesized, ligated with the expression vector, pQE16, and transformed into E. coli JM109 and DH5alpha. SDS-PAGE analysis and Western-blotting detection demonstrated that the peptide CEI12 (fused with dihydrofolate reductase [DHFR]) was specifically expressed only in E. coli JM109 with IPTG induction. The expression profiles of the AHP CEI12 at different IPTG concentrations and different inducing times demonstrated no significant differences by SDS-PAGE analysis. The expression level of CEI12 (fused with DHFR) was about 500 microg/L culture.