Daniel Dostaler

GENETIC DIVERSITY AMONG FUSARIUM GRAMINEARUM STRAINS FROM ONTARIO AND QUEBEC

The random amplified polymorphic DNA (RAPD) method was used to sample DNA markers from 72 strains of Fusarium graminearum isolated from wheat blighted kernels collected from Quebec (52 strains), Ontario (18 strains), and Prince Edward Island (2 strains). Sixty-five markers generated with eight RAPD primers showed that all strains were genetically distinct. Moreover, the analysis of molecular variance (AMOVA) indicated that 90.56% of the genetic variability associated with strains used in this study was explained by within-region variation. The GST values were low and showed that there was almost no genetic differentiation associated with sampling F. graminearum either from two different years in Quebec (GST = 0.0375) or from Ontario and Quebec (GST = 0.0509). These results show that F. graminearum strains from Quebec and Ontario might be part of a single population pool.

Discrimination between alfalfa and potato isolates of Verticillium albo-atrum using RAPD markers

Random amplified polymorphic DNA (RAPD) of total DNA was used to study genetic variability within 35 alfalfa and potato isolates of Verticillium albo-atrum , the causal agent of Verticillium wilt. With five selected RAPD primers, patterns were clearly different between the alfalfa and the potato isolates. A significant (37%; P V. albo-atrum and support the creation of a distinct taxonomic entity for alfalfa isolates. In addition, one avirulent potato isolate and one alfalfa isolate were tested and found divergent according to RAPD patterns.

Variabilité phénétique du Colletotrichum graminicola du sorgho

A comparative intraspecific study of Colletotrichum graminicola (Ces.) G.W. Wilson from sorghum (Sorghum bicolor (L.) Moench) was carried out. Thirty one isolates were used, including 29 from various sites in Burkina Faso and 2 from the American Type Culture Collection (one from sorghum of Porto Rico and the second from maize of Alabama). The analysis of physiological (radial growth on agar media, biomass production, sensitivity to benomyl) and pathogenic (virulence towards sorghum seedlings) characteristics revealed high differences between isolates for each variable. Single linkage cluster analysis showed that C. graminicola exhibits a continuous variability in Burkina Faso. Euclidean distances spread from 0.67 to 3.59 and isolates were distributed in five distinct groups at a distance of 2.20 in the phenogram. Most isolates were found in one single group. The two control isolates from the American Type Culture Collection were apart from those of Burkina Faso, but were distinct one from the other as well. Neither the year of isolation, nor the isohyet of origin, nor the inoculum source (seed or leaf) seemed to be associated with the clustering of isolates.