Genetic variability of Fusarium fujikuroi populations associated with bakanae of rice in Italy

Abstract

The heterothallic ascomycete Fusarium fujikuroi (teleomorph: Gibberella fujikuroi) is the causal agent of bakanae of rice, a disease of increasing economic importance in the major rice‐producing areas in the world and a serious threat for Italian rice cultivation. A few studies have characterized F. fujikuroi isolates in America and the Philippines but no data are available on the genetic structure of Italian pathogen populations. Microsatellite SSRs are useful tools to study the intraspecific diversity at population level. In this study, 19 polymorphic SSRs have been identified and applied to characterize the genetic variation of 334 isolates of F. fujikuroi coming from eight Italian rice‐growing areas. A high degree of diversity at haplotype level has emerged: in the eight populations, 107 unique haplotypes were scored. Analysis of molecular variance (amova) showed that 98% of genetic variability occurred within F. fujikuroi Italian populations, as confirmed by the allelic Shannon index ranging from 0.56 to 1.06. The presence of a 1:1 ratio of mating type alleles in six out of eight of the Italian fungal populations suggests a potential for sexual reproduction in the field. However, the high fraction of clonality (43%), confirmed by neighbour‐joining clustering analysis, and the high level of linkage disequilibrium observed, indicates that reproduction of F. fujikuroi is mostly clonal in Italy. All data suggest that the observed genetic variability was probably mediated by human activity and transmission by rice seeds.

The puzzle of bakanae disease through interactions between Fusarium fujikuroi and rice

“…Different degrees of virulence were observed among the F. fujikuroi strains from the same cultivation area and from the same cultivars, thus indicating the possible influence of genetic features of the strains, rather than the involvement of environmental factors. Fusarium fujikuroi genetic structure is mainly clonal in Italy, but the 1:1 ratio of mating type alleles found in 6 out of 8 Italian fungal populations indicates that sexualreproduction of F. fujikuroi may occur in the field (29). Similar coexistence of both mating types was also observed within F. fujikuroi populations in Taiwan (7).…”

“…To this end, molecular techniques were initially developed using random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP) techniques, and electrophoretic karyotype analysis to separate Fusarium isolates with different degrees of virulence, and to distinguish among the different species of GFSC (32,33). Recently, a set of various polymorphic simple sequence repeat (SSR) marker have been developed as a sensitive molecular technique for characterization of the genetic variation among different F. fujikuroi populations (7,29).…”

Identification and pathogenicity of Fusarium species associated with pokkah boeng of sugarcane in Brazil

“…The role of gibberellic acid as a virulence factor remains to be elucidated. Symptoms of bakanae in rice were evaluated using a diagrammatic scale, according to different symptoms of the disease (Amatulli et al ., ; Valente et al ., ). This was not possible with symptoms of pokkah boeng observed in this study, because they are too variable.…”

Genetic diversity among Fusarium species associated with sorghum stalk rot in Southern Ethiopia

“…Despite continued efforts to manage diseases caused by Fusaria, they still pose serious threats to grain producers across the world (Brandfass and Karlovsky, 2008). Since the early reports by Wollenweber and Reinking (1935), lots of researches have been conducted on the taxonomy/genetic diversity of the genus Fusarium (Summerell et al, 2011;O'Donnell et al, 2015;Laurence et al, 2016;Moussa et al, 2017 andValente et al, 2017). However, research on Fusarium spp.…”