RESUMO
Citrus canker is a major disease caused by Xanthomonas citri pv. citri. Snakin-1 is an antimicrobial peptide, which was previously shown to be effective against different bacterial and fungal diseases in potato, wheat and lettuce when expressed in transgenic plants. We generated transgenic Citrange Troyer citrus rootstocks constitutively expressing this peptide and 5 different transgenic lines were challenged against virulent X. citri isolates. Challenge assays conducted in vitro using detached leaves and in planta by infiltration revealed a significant reduction of the number and size of canker lesions in some of the transgenic lines.
Assuntos
Anti-Infecciosos , Citrus , Solanum tuberosum , Xanthomonas , Doenças das Plantas , Solanum tuberosum/genética , Xanthomonas/genéticaRESUMO
KEY MESSAGE: The novel sunflower gene HaGLP1 is the first germin-like protein characterized from the family Asteraceae. It alters the host redox status and confers protection against Sclerotinia sclerotiorum and Rhizoctonia solani. Germin-like proteins (GLPs) are a large, diverse and ubiquitous family of plant glycoproteins belonging to the Cupin super family. These proteins have been widely studied because of their diverse roles in important plant processes, including defence. The novel sunflower gene HaGLP1 encodes the first germin-like protein characterized from the family Asteraceae. To analyse whether constitutive in vivo expression of the HaGLP1 gene may lead to disease tolerance, we developed transgenic Arabidopsis plants that were molecularly characterized and biologically assessed after inoculation with Sclerotinia sclerotiorum or Rhizoctonia solani. HaGLP1 expression in Arabidopsis plants conferred tolerance to S. sclerotiorum at the first stages of disease and interfered with R. solani infection, thus giving rise to significant protection against the latter. Furthermore, HaGLP1 expression in Arabidopsis plants elevated endogenous ROS levels. HaGLP1-induced tolerance does not appear to be related to a constitutive induction of the plant defence or the ROS-related genes examined here. In conclusion, our data suggest that HaGLP1 is an interesting candidate for the engineering of plants with increased fungal tolerance and that this gene could also be useful for the selection of naturally overexpressing sunflower genotypes for conventional breeding purposes.
Assuntos
Arabidopsis/metabolismo , Arabidopsis/microbiologia , Ascomicetos/fisiologia , Glicoproteínas/metabolismo , Helianthus/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Glicoproteínas/genética , Helianthus/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismoRESUMO
Genetically engineered expression of replicase encoding sequences has been proposed as an efficient system to confer protection against virus diseases by eliciting protection mechanisms in the plant. Potato leaf-roll was one of the first diseases for which this kind of protection was engineered in potato plants. However, details of the protecting mechanism were not reported, so far. The ORF2b of an Argentinean strain of PLRV was cloned and sequenced finding 94% and 97% of homology with Australian and Dutch strains, respectively. To elucidate the mechanism of protection against PLRV infection, three versions of ORF2b (non-translatable sense, translatable sense with an engineered ATG and antisense) were constructed under the control of the 35S CaMV promoter and the nos terminator and introduced in potato plants (cv. Kennebec) by Agrobacterium tumefaciens-mediated transformation. Grafting infection experiments showed that resistant transgenic plants could be obtained with any of the constructs, suggesting that the mechanism of protection is independent of the expression of protein and is RNA mediated. Field trial infection confirmed that resistant transgenic events were obtained. Biolistic transient transformation experiments of leaves derived from transgenic plants using a gene coding for the fusion protein GUS-ORF2b, followed by scoring of the number of GUS expressing leaf spots, supported that the protection is mediated by a post-transcriptional gene silencing mechanism.
Assuntos
Inativação Gênica , Luteovirus/genética , Plantas Geneticamente Modificadas/virologia , RNA Polimerase Dependente de RNA/genética , Solanum tuberosum/virologia , Transformação Genética , Clonagem Molecular , Luteovirus/enzimologia , Dados de Sequência Molecular , Fases de Leitura Aberta , Homologia de Sequência do Ácido Nucleico , Solanum tuberosum/genéticaRESUMO
Asr is a family of genes that maps to chromosome 4 of tomato. Asr2, a recently reported member of this family, is believed to be regulated by abscisic acid (ABA), stress and ripening. A genomic Asr2 clone has been fully sequenced, and candidate upstream regulatory elements have been identified. To prove that the promoter region is functional in vivo, we fused it upstream of the beta-glucuronidase (GUS) reporter gene. The resulting chimeric gene fusion was used for transient expression assays in papaya embryogenic calli and leaves. In addition, the same construct was used to produce transgenic tomato, papaya, tobacco, and potato plants. Asr2 upstream sequences showed promoter function in all of these systems. Under the experimental conditions tested, ABA stimulated GUS expression in papaya and tobacco, but not in tomato and potato systems.