This work aimed at characterizing nine Xop effectors present in Xam CIO151 for their role in virulence and modulation of plant immunity. Xam strain CIO151 has 17 predicted T3Es belonging to the Xanthomonas outer protein class (Xop). Xam, like other Xanthomonas species, requires type III effectors (T3Es) for maximal virulence. manihotis (Xam) causes cassava bacterial blight, the most important bacterial disease of cassava. The results should help to improve selection of sources of resistance to cassava bacterial blight. Different pathotypes were defined among the 26 isolates and differential cultivars were proposed to define the pathotypic composition of Xam populations in three ECZs in Colombia. A highly significant interaction was also detected when cultivar behaviour was rated as area under the disease progress curve (AUDPC) after stem inoculation.
The stem inoculation technique was selected as a method for resistance screening of cassava cultivars for bacterial blight resistance. Cultivar × isolate interaction was highly significant (P < 0♰01) after stem inoculation, but not after leaf inoculation. Leaf inoculation and stem puncture were used in order to detect possible specific interactions between cultivars and isolates. A set of 26 Xam isolates from three edaphoclimatic zones (ECZs) in Colombia was selected for inoculation on a set of 17 potential cassava differentials. Although Colombian isolates of Xam differ in DNA polymorphism and pathogenicity, no suitable host differentials have been identified to demonstrate physiological specialization. manihotis (Xam) is a destructive disease occurring in most cassava growing-areas.
Cassava bacterial blight, caused by Xanthomonas axonopodis pv.
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