Institution: | 1. Instituto de Biología Molecular y Celular de Rosario (IBR)—Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ocampo y Esmeralda S/N, S2002LRK Rosario, Argentina
Área Virología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 590, S2002LRK Rosario, Argentina
Facultad de Ciencias Agrarias, Universidad Nacional del Litoral, Producción Vegetal, Kreder 2805, 3080 HOF Esperanza, Santa Fe, Argentina;2. Instituto de Biología Molecular y Celular de Rosario (IBR)—Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ocampo y Esmeralda S/N, S2002LRK Rosario, Argentina;3. Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-C.S.I.C, Ingeniero Fausto Elio, S/N, 46022 Valencia, España;4. Instituto de Biología Molecular y Celular de Rosario (IBR)—Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ocampo y Esmeralda S/N, S2002LRK Rosario, Argentina
Área Virología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 590, S2002LRK Rosario, Argentina |
Abstract: | Citrus is an economically important fruit crop that is severely afflicted by citrus canker, a disease caused by Xanthomonas citri ssp. citri (X. citri); thus, new sustainable strategies to manage this disease are needed. Although all Citrus spp. are susceptible to this pathogen, they are resistant to other Xanthomonas species, exhibiting non-host resistance (NHR), for example, to the brassica pathogen X. campestris pv. campestris (Xcc) and a gene-for-gene host defence response (HDR) to the canker-causing X. fuscans ssp. aurantifolii (Xfa) strain C. Here, we examine the plant factors associated with the NHR of C. limon to Xcc. We show that Xcc induced asymptomatic type I NHR, allowing the bacterium to survive in a stationary phase in the non-host tissue. In C. limon, this NHR shared some similarities with HDR; both defence responses interfered with biofilm formation, and were associated with callose deposition, induction of the salicylic acid (SA) signalling pathway and the repression of abscisic acid (ABA) signalling. However, greater stomatal closure was seen during NHR than during HDR, together with different patterns of accumulation of reactive oxygen species and phenolic compounds and the expression of secondary metabolites. Overall, these differences, independent of Xcc type III effector proteins, could contribute to the higher protection elicited against canker development. We propose that Xcc may have the potential to steadily activate inducible defence responses. An understanding of these plant responses (and their triggers) may allow the development of a sustained and sustainable resistance to citrus canker. |