ISSR and AFLP characterization of Phomopsis amygdali ((Del.) Tuset & Portilla Accessions

Carlier, Jorge; Cabrita, L.; Leitão, José; Sousa, R. M.; Sousa, A. T.

http://hdl.handle.net/10400.1/6498

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Abstract(s)

The fungus Phomopsis amygdali (Del.) Tuset & Portilla (sin: Fusicoccum amygdali Delacr.) is one of the most important almond (Prunus dulcis (Mill.) Webb) diseases in Portugal, causing cankers on one-year-old branches, and wilting and death of infected twigs and shoots. The disease leads frequently to tree decline and death. In the Algarve region of Portugal, the most common commercial cultivars show severe damages while some traditional almond cultivars seem not to be significantly affected. Infected plant material was collected from almond and peach trees. Fungi present in the infected tissues were isolated on PDA medium and transferred to the mycotec managed by the Estacao Nacional de Fruticultura Vieira Natividade (ENFVN). Some fungi accessions were identified as Eutypa lata (Pers.: Fr.) Tul. & C. Tul. Seventeen accessions, one identified as Eutypa and sixteen as Phomopsis, were analyzed by ISSR and AFLP techniques. Fourteen Phomospsis accessions, grouped in a main cluster, showed a coefficient of similarity (DICE) over 0.88. One of the putative Phomopsis accessions showed to be erroneously classified as it displays strong genetic similarity (DICE 0.92) to the Eutypa accession, while these two samples presented very low genetic similarity (DICE 0.20) to the main group of Phomopsis accessions. One sample, which we hypothesize to be of Cytospora sp. remained apart (DICE 0.15) from all the other accessions. The identification and cloning of molecular markers specific to each pathogenic species will be of major interest for further rapid identification of the causal agent of canker symptoms in almond.