Electrophoretic karyotype variation among pathotypes of Fusarium oxysporum f.sp. dianthi

Karyotype analysis by pulsed-field gel electrophoresis was applied to characterize isolates of Fusarium oxysporum f.sp. dianthi, the causal agent of Fusarium wilt on carnation. Eleven distinct chromosomal DNA patterns were detected among 38 pathogenic isolates, and the total genome size was estimated to range from 23·7 to 36·4 Mb. Except for isolates belonging to pathotypes 2 and 4, all members of the same pathotype shared overlapping electrophoretic karyotypes. Karyotypes of isolates assigned to pathotypes 1 and 8 showed a high degree of similarity, in accordance with VCG and RFLP analysis. The same electrophoretic karyotype was also shared by members of pathotypes 2 and 5, thus confirming results obtained by both VCG and RFLP grouping, A single representative of pathotype 6, previously confined to the same VCG and RFLP group as pathotypes 2 and 5, had a slightly different chromosomal pattern. Isolates assigned to pathotype 4 showed four related karyotypes which partially differed in both the number and size of chromosomal bands. However, all strains assigned to this pathotype shared a basic profile of nine chromosomal bands, while two low-molecular-weight bands were present or absent. The findings are discussed with regard both to the suitability of race distinction in the case of the special form dianthi of F. oxysporum and to the use of karyotype analysis by PFGE as a tool for the study of the population genetics of this fungu

La capacità repressiva di compost nei confronti della tracheofusariosi del basilico

Alcuni compost, addizionati al suolo o impiegati come componenti di substrati per colture in vaso, possono svolgere un’attività repressiva nei confronti dei patogeni terricoli. Nel biennio 2005-2006 sono stati saggiati, a Grugliasco (TO), in serre in ferro/vetro, compost provenienti da aziende di compostaggio presenti sul territorio piemontese al fine di valutarne la loro capacità repressiva. Dai risultati è emerso l’efficace contenimento nei confronti di F. oxysporum f.sp. basilici, da parte di compost prodotto a partire da rifiuti solidi urbani e fanghi, con una diminuzione fino al 50% di piante morte e un incremento fino al 25% di biomassa prodotta a fine ciclo rispetto a quanto rilevato impiegando un ammendante torboso scelto come riferimento