Pepper BS2 gene is functional in citrus and increases canker resistance

SENDIN, L; ORCE, I; GÓMEZ, R; RUBIO, C; ROMERO, L; ATHAYDE, MG; CASTAGNARO AP.; FILIPPONE, MP

Congreso; International Citrus Congress; 2016

Pepper Bs2 gene confers resistance to Xanthomonas campestris pv. vesicatoria (Xcv) pathogenic strains containing the avrBs2 avirulence gene in susceptible pepper and tomato varieties. The avrBs2 gene is highly conserved among members of the Xanthomonas genus, and the avrBs2 of Xcv shares 96% homology with the avrBs2 of Xanthomonas citri subsp citri, the causal agent of citrus canker disease. A previous study showed that transient expression of pepper Bs2 in lemon leaves reduced canker formation and induced plant defense mechanisms. In this work, the effect of stable expression of Bs2 resistance gene on citrus canker resistance was evaluated in transgenic plants of Citrus sinensis cv. Pineapple. Reduction of disease symptoms of up to 70% was observed in transgenic lines expressing Bs2 with respect to non-transformed control plants. This reduction was directly depending on the Xcc avrBs2 gene since no effect was observed when a mutant strain of Xcc with a disruption in avrBs2 gene was inoculated. Additionally, canker symptoms reduction was correlated with levels of Bs2 expression in transgenic plants, as assessed by real-time qPCR, and accompanied by production of reactive oxygen species. These results indicate that pepper Bs2 resistance gene is also functional in other different family to Solanaceae, and could be considered for canker control.