Inducible expression of Bs2 R gene from Capsicum chacoense in sweet orange (Citrus sinensis L. Osbeck) confers enhanced resistance to citrus canker disease

LORENA NOELIA SENDÍN; INGRID GEORGINA ORCE; ROCÍO LILIANA GÓMEZ; RAMÓN ENRIQUE; CARLOS FROILÁN GRELLET BOURNONVILLE; ALDO SERGIO NOGUERA; ADRIÁN ALBERTO VOJNOV; MARÍA ROSA MARANO; LUCIANO RIGANO, CAROLINE PAYETTE, GENEVIÈVE BROUILLARD, MARIA ROSA MARANO, LAURA ABRAMOWICZ, PABLO TORRES, MAXIMINA YUN, ATILIO PEDRO CASTAGNARO, MOHAMED ELOIRDI, MATHIEU LANGLOIS, JOHN MAXWELL DOW, KAMAL BOUARAB AND ADRIAN VOJNOV.; MARÍA PAULA FILIPPONE

PLANT MOLECULAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2017

0167-4412

Transgenic expression of the pepper Bs2 geneconfers resistance to Xanthomonas campestris pv. vesicatoria(Xcv) pathogenic strains which contain the avrBs2avirulence gene in susceptible pepper and tomato varieties.The avrBs2 gene is highly conserved among members ofthe Xanthomonas genus, and the avrBs2 of Xcv shares 96%homology with the avrBs2 of Xanthomonas citri subsp.citri (Xcc), the causal agent of citrus canker disease. A previousstudy showed that the transient expression of pepperBs2 in lemon leaves reduced canker formation and inducedplant defence mechanisms. In this work, the effect of thestable expression of Bs2 gene on citrus canker resistancewas evaluated in transgenic plants of Citrus sinensis cv.Pineapple. Interestingly, Agrobacterium-mediated transformationof epicotyls was unsuccessful when a constitutivepromoter (2× CaMV 35S) was used in the plasmid construction,but seven transgenic lines were obtained with agenetic construction harbouring Bs2 under the control ofa pathogen-inducible promoter, from glutathione S-transferasegene from potato. A reduction of disease symptomsof up to 70% was observed in transgenic lines expressingBs2 with respect to non-transformed control plants. Thisreduction was directly dependent on the Xcc avrBs2 genesince no effect was observed when a mutant strain of Xccwith a disruption in avrBs2 gene was used for inoculations.Additionally, a canker symptom reduction was correlatedwith levels of the Bs2 expression in transgenic plants, asassessed by real-time qPCR, and accompanied by the productionof reactive oxygen species. These results indicatethat the pepper Bs2 resistance gene is also functional in a family other than the Solanaceae, and could be consideredfor canker control.