The overexpression of RXam1, a cassava gene coding for an RLK, confers disease resistance to Xanthomonas axonopodis pv. manihotis
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The overexpression of RXam1 leads to a reduction in bacterial growth of XamCIO136, suggesting that RXam1 might be implicated in strain-specific resistance.
Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) is a prevalent disease in all regions, where cassava is cultivated. CBB is a foliar and vascular disease usually controlled through host resistance. Previous studies have found QTLs explaining resistance to several Xam strains. Interestingly, one QTL called XM5 that explained 13% of resistance to XamCIO136 was associated with a similar fragment of the rice Xa21-resistance gene called PCR250. In this study, we aimed to further identify and characterize this fragment and its role in resistance to CBB. Screening and hybridization of a BAC library using the molecular marker PCR250 as a probe led to the identification of a receptor-like kinase similar to Xa21 and were called RXam1 (Resistance to Xam 1). Here, we report the functional characterization of susceptible cassava plants overexpressing RXam1. Our results indicated that the overexpression of RXam1 leads to a reduction in bacterial growth of XamCIO136. This suggests that RXAM1 might be implicated in strain-specific resistance to XamCIO136.
KeywordsCassava bacterial blight Pattern-recognition receptor Plant immunity R genes Receptor-like kinases Transgenic cassava
Days post inoculation
Cassava bacterial blight
Elongation factor receptor
Microbe-associated molecular pattern
Quantitative trait loci
Xanthomonas axonopodis pv. manihotis
This research was supported by Colciencias (110152128399). PADT was supported with a scholarship for graduated students from Universidad Nacional de Colombia. The authors would like to acknowledge Rosa Juliana Gil for careful and critical reading of the manuscript, Camilo Dorado for his support on the statistical analysis and Fabio Gómez for his support on the molecular cloning of RXam1. The authors have no conflict of interest to declare.
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