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A Novel, Sensitive Method to Evaluate Potato Germplasm for Bacterial Wilt Resistance Using a Luminescent Ralstonia solanacearum Reporter Strain

March 2014 , Volume 27 , Number  3
Pages  277 - 285

Andrea Paola Zuluaga Cruz,1,2 Virginia Ferreira,3 María Julia Pianzzola,3 María Inés Siri,3 Núria S. Coll,2 and Marc Valls1,2

1Departament de Genètica, Universitat de Barcelona, Av. Diagonal 643, Catalonia, Spain; 2Centre for Research in Agricultural Genomics (CRAG), Edifici CRAG, Campus UAB, 08193 Bellaterra, Catalonia, Spain; 3Cátedra de Microbiología, Dep. de Biociencias, Facultad de Química, Universidad de la República, Av. Gral. Flores 2124, CP11800, Montevideo, Uruguay

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Accepted 20 November 2013.

Several breeding programs are under way to introduce resistance to bacterial wilt caused by Ralstonia solanacearum in solanaceous crops. The lack of screening methods allowing easy measurement of pathogen colonization and the inability to detect latent (i.e., symptomless) infections are major limitations when evaluating resistance to this disease in plant germplasm. We describe a new method to study the interaction between R. solanacearum and potato germplasm that overcomes these restrictions. The R. solanacearum UY031 was genetically modified to constitutively generate light from a synthetic luxCDABE operon stably inserted in its chromosome. Colonization of this reporter strain on different potato accessions was followed using life imaging. Bacterial detection in planta by this nondisruptive system correlated with the development of wilting symptoms. In addition, we demonstrated that quantitative detection of the recombinant strain using a luminometer can identify latent infections on symptomless potato plants. We have developed a novel, unsophisticated, and accurate method for high-throughput evaluation of pathogen colonization in plant populations. We applied this method to compare the behavior of potato accessions with contrasting resistance to R. solanacearum. This new system will be especially useful to detect latency in symptomless parental lines before their inclusion in long-term breeding programs for disease resistance.

© 2014 The American Phytopathological Society