Fusarium oxysporum f. sp. lavandulae, a novel forma specialis causing wilt on Lavandula × allardii

Ortu, Giuseppe; Bertetti, Domenico; Gullino, M. Lodovica; Garibaldi, Angelo

Fusarium oxysporum f. sp. lavandulae, a novel forma specialis causing wilt on Lavandula × allardii

2018

Ortu, Giuseppe | Bertetti, Domenico | Gullino, M. Lodovica (Maria Lodovica) | Garibaldi, Angelo

Symptoms of a vascular wilt were observed on many plants of Lavandula × allardii (hybrid of Lavandula dentata and L. latifolia) cultivated in a nursery near Albenga, Liguria region, Northern Italy. After identification based on morphological characteristic and ITS sequence analysis, the pathogen was identified as Fusarium oxysporum. Eight single-spore isolates obtained from infected tissues were used for a phylogenetic analysis in order to identify the forma specialis. Translation elongation factor 1-α (EF-1α), intergenic spacer (IGS) and three genes encoding for polygalacturonase genes (pg1, pg5 and pgx1) were amplified by PCR. Gene sequences were aligned with other formae speciales of Fusarium oxysporum obtained from GenBank databases in order to build phylogenetic trees. Results obtained for each genomic region showed a unique group with isolates derived from L. × allardii well separated from the other formae speciales. Results obtained, together with pathogenicity tests, allowed us to introduce a new forma specialis named F. oxysporum f. sp. lavandulae.

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