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Panax ginseng is a valuable medicinal plant which is affected by many diseases during its long cultivation period. Ginseng root rot, caused by Fusarium oxysporum, has become severe in China. This soilborne pathogen comprises many formae speciales based on host specificity. Ten representative isolates from diseased ginseng rot root showed pathogenicity on ginseng. To identify the forma specialis of the F. oxysporum strains, host range tests of three representative isolates were carried out on nine plant species. All three isolates caused severe symptoms only on ginseng, but only slight or no visual symptoms on the other eight hosts, indicating that the strains were host-specific to ginseng. Phylogenetic trees were constructed based on sequences of the translation elongation factor 1-α (EF-1α) gene, two endopolygalacturonase genes (Pg1, Pg5) and two exopolygalacturonase genes (Pgx1 and Pgx4). The ten F. oxysporum isolates from ginseng clustered into a unique group clearly separated from other formae speciales already described. Based on the host range tests and phylogenetic analyses, the isolates of F. oxysporum derived from ginseng have been identified as a new forma specialis, designated Fusarium oxysporum f. sp. ginseng. This is the first report of forma specialis of F. oxysporum on ginseng.

Symptoms of a new vascular wilt were observed on several plants of Papaver nudicaule cultivated at the Regional Institute for Floriculture in Sanremo and in a nursery near Ventimiglia, Liguria region, Northern Italy. Morphology and ITS sequence analysis characterize the pathogen as Fusarium oxysporum. To identify the forma specialis, eight isolates obtained from infected tissues were used for a phylogenetic analysis based on translation elongation factor 1-α (EF-1α) gene and four polygalacturonase genes (Pg1, Pg5, Pgx1 and Pgx4). After amplification by PCR, the gene sequences were aligned with corresponding sequences from other formae speciales of Fusarium oxysporum obtained from GenBank databases in order to build phylogenetic trees. Results obtained for each genomic region showed that the isolates derived from P. nudicaule form a unique group well separated from other formae speciales. To our knowledge, this is the first report of F. oxysporum on P. nudicaule and together with the phylogenetic analysis and positive pathogenicity tests permits us to introduce a new forma specialis named F. oxysporum f. sp. papaveris.

analysis based on the ITS region confirmed the pathogen as Fusarium oxysporum. In order to identify the forma specialis, thirteen isolates obtained from infected tissues were used for phylogenetic analysis based on four polygalacturonase genes (Pg1, Pg5, Pgx1 and Pgx4) together with the translation elongation factor 1-alpha (EF-1alpha) gene. Sequences generated in this study were aligned with other formae speciales of Fusarium oxysporum from GenBank to construct phylogenetic trees. Eleven isolates of a new forma specialis, Fusarium oxysporum f. sp. crassulae described on Crassula ovata, were added to the analysis based on Pg5 and Pgx1 genes. The results obtained for each genomic region showed that the isolates derived from E. agavoides are in a unique group well separated from other formae speciales already described. The first report of F. oxysporum on E. agavoides together with the results obtained in this study suggest a new forma specialis, here named F. oxysporum f. sp. echeveriae.

Symptoms of a new vascular wilt were observed on several plants of Papaver nudicaule cultivated at the Regional Institute for Floriculture in Sanremo and in a nursery near Ventimiglia, Liguria region, Northern Italy. Morphology and ITS sequence analysis characterize the pathogen as Fusarium oxysporum. To identify the forma specialis, eight isolates obtained from infected tissues were used for a phylogenetic analysis based on translation elongation factor 1-α (EF-1α) gene and four polygalacturonase genes (Pg1, Pg5, Pgx1 and Pgx4). After amplification by PCR, the gene sequences were aligned with corresponding sequences from other formae speciales of Fusarium oxysporum obtained from GenBank databases in order to build phylogenetic trees. Results obtained for each genomic region showed that the isolates derived from P. nudicaule form a unique group well separated from other formae speciales. To our knowledge, this is the first report of F. oxysporum on P. nudicaule and together with the phylogenetic analysis and positive pathogenicity tests permits us to introduce a new forma specialis named F. oxysporum f. sp. papaveris. [ABSTRACT FROM AUTHOR]