Transgenic expression of the rice Xa21 pattern‐recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum

Abstract

Summary 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, bio-control 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 plants in the glass house for resistance against Xcm. About fifty percent of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the non-transgenic 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.

Quantitative, image-based phenotyping methods provide insight into spatial and temporal dimensions of plant disease

“…Elucidating the molecular mechanisms that govern host-microbe interactions has a robust track record of leading to the development of new and effective resistance strategies. For example, plant innate immunity employs several tiers of receptors that, at least in some instances, can be transferred among species (Tai et al, 1999;Zhao et al, 2005;Lacombe et al, 2010;Tripathi et al, 2014;Schoonbeek et al, 2015). Similarly, molecular dissection of the mechanisms used by pathogens to induce susceptibility has led to the development of biotechnology methods for blocking pathogenesis (Li et al, 2012;Strauss et al, 2012;Boch et al, 2014).…”

Pattern Recognition Receptors—Versatile Genetic Tools for Engineering Broad-Spectrum Disease Resistance in Crops

“…and sweet orange (Citrus sinensis) confers increased resistance against different Xanthomonas spp. [58,59] and expression of the PRR ELR from a wild potato species renders cultivated potato (Solanum tuberosum) more resistant to the oomycete pathogen Phytophthora infestans [60]. Taken together, these results demonstrate that addition of only a single PRR can already significantly enhance resistance of plants to adapted pathogens.…”

The durable wheat disease resistance gene Lr34 confers common rust and northern corn leaf blight resistance in maize

“…Similarly, the rice receptor‐like kinase (RLK) gene Xa21 has been shown to provide Banana Xanthomonas wilt resistance in banana (Tripathi et al . ). The nonhost resistance NHR‐linked Arabidopsis genes PING 4 (coding for a phospholipase‐like protein (EARLI4‐like)), PING 5 (coding for a leucine‐rich repeat protein kinase) and PING 6 (coding for an ankyrin repeat family protein), known to provide pre‐invasion resistance to nonadapted fungal pathogens, have been transferred into soya bean where they confer Asian soya bean rust resistance (Langenbach et al ., ).…”