Pathogenicity of Strains of the C Group and B Group of Xanthomonas axonopodis in Duncan Grapefruit (Citrus paradisi Macf) and Key Lime (C. aurantifolia Swing.)
Citrus canker is caused by several groups of strains of Xanthomonas axonopodis (Xac). The C type canker, caused by C-group strains has been reported only in Brazil infecting Key lime C. aurantifolia (Christm) Swingle. The B-type canker, caused by B-group strains occurred on lemon C. limon (L.)Burmf. in Argentina from 1929 and was not found anymore after 1991. The C-group strains cause necrosis similar to the hypersensitive reaction (HR) in grapefruit (C. paradisi Macf) leaves, whereas the B-group strains cause a pathogenic reaction (PR) in grapefruit. The objective was to characterize the reactions of the different type of strains in both hosts by electrolyte leakage and population growth. We compared data from C and B strains on Duncan grapefruit (DG) and Key lime (KL). Two-week-old leaves were infiltrated and electrolyte leakage and population growth quantified at different times after inoculation. Inoculum of 108bacterial cells per ml of the C strain gave a conductivity of 154. 3μmho in the intercellular fluid of DG leaves after 72 hours of infiltration and the same values in KL only after 8 days, whereas the B strain gave 13.5 in DG and 48.3 in KL at 72 hours. Inoculum of 104 bacterial cells per ml of the C strain grew to 8.4 cell/cm2 after 2 weeks in DG when multiplication ceased and to 1. 1×103 cell/cm2 in KL at that time and continued growing. In contrast the B strain grew to 2. 5×105 in DG and 2.4×106 cell/cm2 in KL, both after 7 days. Fast electrolyte leakage and lack of growth to high levels are typical of an HR single-gene resistant reaction of C-strain in DG. Slow electrolyte leakage and continued growth to high levels are pathogenic reactions of C in KL and of B in DG and KL.
Citrus canker Xanthomonas axonopodis pv. citri Hypersensitive reaction
A. M. Gochez M. A. Rinsdahl-Canavosio B. I. Canteros
Estacion Experimental Agropecuaria Bella Vista, Institute National de Tecnologia Agropecuaria INTA, Bella Vista,Ctes. 3432, Argentina
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
1103-1106
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）