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Phytophthora betacei and Phytophthora andina: controversy within the Clade 1c?

Silvia Restrepo: Universidad de los Andes

<div>In South America, late blight is one of the main threats to several domesticated and semi-domesticated crops. A recently described species, <em>Phytophthora betacei, </em>has been found causing symptoms akin to late blight on tree tomato crops (<em>Solanum betaceum</em>) in Colombia. The description of this new species led us to redefine the previously described polyphyletic species <em>P. andina.</em> This species has been controversial since its designation It has been hypothesized to have arisen from hybridization based on the conflicting phylogenetic information of mitochondrial and nuclear genealogies. Other researchers have considered that the polyphyletic nature of the mitochondrial alleles renders <em>P. andina</em> an invalid species. The identification of <em>P. betacei</em> as a different species from <em>P. infestans</em> sheds some light on the origin of <em>P. andina</em>. In this study we describe the biology, the life cycle, the disease cycle, the sexual incompatibilities, the distribution and several physiological responses, including fungicides’ responses, of the new species, <em>P. betacei</em>. All results suggest that indeed, <em>P. betacei </em>is a separate species, where pre- and postzygotic mechanisms played a role in the speciation process. We also explored the genome of <em>P. betacei</em> and discussed the possible causes of its expansion and the mechanisms used to infect its only described host, <em>Solanum betaceum. </em></div>

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