title: Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.
abstract: Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa.
authors.affiliation: International Institute of Tropical Agriculture (IITA), Nairobi, Kenya.
authors.forename: Jaindra N
authors.initials: JN
authors.lastname: Tripathi
authors.forename: Jim
authors.initials: J
authors.lastname: Lorenzen
authors.forename: Ofir
authors.initials: O
authors.lastname: Bahar
authors.forename: Pamela
authors.initials: P
authors.lastname: Ronald
authors.forename: Leena
authors.initials: L
authors.lastname: Tripathi
mesh_terms: D001681:Biological Assay; D004269:DNA, Bacterial / Q000235:genetics; D060467:Disease Resistance / Q000276:immunology*; D018506:Gene Expression Regulation, Plant; D028521:Musa / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D009876:Operon / Q000235:genetics; D012275:Oryza; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051192:Receptors, Pattern Recognition / Q000378:metabolism*; D012038:Regeneration; D015203:Reproducibility of Results; D016959:Xanthomonas campestris / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D010940:Plant Proteins; D051192:Receptors, Pattern Recognition; C036483:T-DNA; C097148:Xa21 protein, Oryza sativa; D017346:Protein Serine-Threonine Kinases
keywords: Xa21; Xanthomonas campestris pv. musacearum; banana Xanthomonas wilt; rice pattern-recognition receptor; transgenic banana