J Appl Genetics (2012) 53:237–247 gene was sequenced. The sequences were compared with sequences deposited in the Fusarium ID database. The com- parison with the TEF sequence in the Fusarium ID database showed 100% matching of all isolates examined with F. oxysporum, confirming the species identity (Table 1). Evaluation of mycotoxins level HPLC analysis revealed that the majority of F. oxysporum isolates produce both MON and FB1. The results of one-way ANOVA indicate that isolates differ significantly in their toxigenic activity and mycotoxin profile (Table 2). FB1 was determined in the concentration range 0.01–0.91 μg g−1 (mean 0.19 μg g−1), while MON was detected in the range 0.5–1,007.47 μg g−1 (mean 115.93 μg g−1). Fumonisin B1 and moniliformin were formed in the highest concentrations by isolates O-10 and O-15, respectively (Table 3). Reference isolate (O-310 DSM-62287) produced only FB1 at a concen- tration of 0.2 μg g−1. The FB1 biosynthesis level allowed to distinguish between four homogeneous groups among 31 isolates (Table 3). Two homogeneous groups (first group: O-15 isolate; second group: other isolates) were distinguished based on differences in the MON level (Table 3). Only four isolates (O-05, O-23, O-24 and O-26) did not form mycotoxins. The correlation between FB1 and MON was not statistically significant (r0 0.113, P0 0.544). Mating type assessment by PCR In the examined set of F. oxysporum isolates, DNA sequences encoding MAT1-1 or MAT1-2 genes were detected (Fig. 1). Isolates O-04, O-07, O-13, O-20, O-21, O-24, O-25, O-26, O- 28 and O-30 for which a 200-bp fragment was amplified with ALPHA primers were designated the MAT1-1 type. The remaining 21 isolates for which a 260-bp PCR product was amplified with HMG primer pairs were designated MAT1-2. Table 1 Isolates displaying the highest and lowest toxin con- centrations with 100% sequence matching with Fusarium oxysporum from the Fusarium ID database O-08 O-10 O-12 O-15 O-17 O-18 O-21 O-25 O-27 O-28 O-29 O-30 0.5 0.9 0.5 0.3 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.2 241 Table 2 Mean squares from the analysis of variance (ANOVA) for FB1 and MON concentrations (μg g−1) for F. oxysporum isolates of asparagus spears origin Source of variation Degrees of freedom Biosynthesis of toxins FB1 0.133*** 0.027 MON 101,576*** 6,174 Isolates Residual 30 62 ***Statistically significant (P<0.001) The relationships between MAT1-1 and mycotoxins biosyn- thesis were not statistically significant (t0 −1.11, P0 0.275 and t0−0.65, P0 0.524 for FB1 and MON concentrations, respec- tively). Similarly, the correlation between MAT1-2 and toxins biosynthesis was not statistically significant (t0 1.11, P0 0.275 and t 0 0.65, P 0 0.524 for FB1 and MON concentrations, respectively). Genetic variability determination To assess a genetic variation among F. oxysporum isolates, genetic fingerprinting by RAPD analyses with nine arbitrary primers was carried out. Three of them were excluded from further analysis because of monomorphism or low repeatabil- ity. Finally, 33 polymorphic products were obtained, ranging from 4 to 7 per primer (Table 4). The size of the RAPD fragments ranged from 0.15 to 3.2 kbp. The relationship among isolates of F. oxysporum is presented in the form of a dendrogram (Fig. 2). Clustering analysis resolved two groups at the 30% similarity level. Each of these groups was divided into smaller subgroups at 60 and 52% similarity levels, respec- tively. The highest genetic similarity (equal to 1) was observed between the isolates O-03 and O-10, O-7 and O-30, O-13 and O-16, O-17 and O-27, and O-18 and O-19, whereas Isolate FB1 (μg g−1) MON (μg g−1) Fusarium ID isolates with 100% homology in the TEF sequence Source of Fusarium ID isolates 60.2 16.1 9.8 1,007.5 0.6 0.5 0.0 2.4 0.0 0.0 171.6 182.8 FD_00056 (F. oxysporum) FD_00705 (F. oxysporum) FD_00056 (F. oxysporum) FD_00805 (F. oxysporum) FD_00446 (F. oxysporum) FD_00446 (F. oxysporum) FD_00070 (F. oxysporum) FD_00805 (F. oxysporum) FD_00705 (F. oxysporum) FD_00802 (F. oxysporum) FD_00805 (F. oxysporum) FD_00705 (F. oxysporum) CBS 175.35 ICMP 5234 CBS 175.35 ICMP 15895 CBS 151.27 CBS 151.27 CBS171.31 ICMP 15895 ICMP 5234 FRC O-1890 ICMP 15895 ICMP 5234