Phytotoxicité de huit mycotoxines associées a la I fusariose de l'épi chez Ie blé 1 F. Eudes, A. Comeau, S. Rioux et J. CollinRésumé : L'étude de huit mycotoxines de Fusarium spp. a une série de concentrations allant de 0 a 4,3 mg/L pour Ie desoxynivalénol, Ie 3-acétyldésoxynivalénol, Ie nivalénol et un fikrat de culture, ou de 0 a 14,3 mg/L pour les toxines T2 et HT2, Ie diacétoxyscirpénol et la zéaralénone, révèle que les trichothécènes sont phytotoxiques. L'inhibition de l'élongation des coléoptiles est bien décrite par des equations linéaires pour chaque trichothécène, lesquelles révèlent des differences importantes de phytotoxicité. Le desoxynivalénol et Ie 3-acétyldésoxynivalénol sont 2,5 fois plus phytotoxiques que le T2, 8 fois plus que le HT2 et 13 fois plus que le diacétoxyscirpénol. Le filtrat de culture, de composition indéfinie mais qui contient a la fois le desoxynivalénol et le 3-acétyldésoxynivalénol, présente la plus fone phytotoxicité. En combinant quatre trichothécènes purifiées, soit le desoxynivalénol, le 3-acétyldésoxynivalénol, le T2 et le nivalénol, nous avons pu distinguer des differences de sensibilité aux trichothécènes parmi 1 l cultivars de blé. De plus, la reduction de l'élongation des segments de coléoptiles de ces cultivars était corrélée avec l'indice de fusariose de l'épi (r = 0,74; P = 0,0068). Abstract:The study of eight mycotoxins from Fusarium spp. at concentrations ranging from 0 to 4.3 mg/L for deoxynivalenol, 3-acetyldeoxynivalenol, nivalénol, and a culture filtrate, and from 0 to 14.3 mg/L for T2 toxin, HT2 toxin, diacétoxyscirpénol, and zéaralénone, demonstrate that trichothécènes are phytotoxic. The inhibition of coleoptile elongation by each trichothecene is well described by a linear equation and these compounds show differences in phytotoxicity. Deoxynivalenol and 3-acetyldeoxynivalenol are 2.5 times more toxic than T2 toxin, 8 times more toxic than HT2 toxin, and 13 times more toxic than diacétoxyscirpénol. The culture filtrate, which contains deoxynivalenol and 3-acetyldeoxynivalenol, is the most toxic to the coleoptile. A mixture of four purified trichothécènes, deoxynivalenol, 3-acetyldeoxynivalenol, T2 toxin, and nivalénol, revealed differences in trichothecene susceptibility among 11 wheat cultivars. Moreover, reduction of coleoptile elongation of these cultivars was correlated with scabsusceptibility (r = 0.74; P = 0.0068).

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A combination of genomic in situ hybridization (GISH) and meiotic pairing analysis of crosses between a series of 2« = 56 partial amphiploids confirmed that the alien genome of the BYDV-immune Agrotricum line OK7211542 is derived from Thinopyrum ponticum and not from Thinopyrum intermedium. The evidence from meiotic pairing analysis indicated that the chromosome constitution of OK7211542 is similar to another Agrotricum line, ORRPX, which was derived from a cross of wheat and Th. ponticum, but different from other Agrotricum lines, Zhong 5 and TAF 46 which were derived from the crosses between wheat and Th. intermedium. The GISH analysis confirmed that OK7211542 contained one complete set of 14 Th. ponticum chromosomes, in which no S chromosome was present in the alien genome. GISH also detected a small alien translocation attached to one of the wheat chromosomes, a result that was consistent with the pairing data.

Different media were evaluated with anthers of five spring wheat (Triticum aestivum L.) genotypes for their ability to produce embryos and green plants in anther culture. Our first experiment showed that the addition of a combination of 19 amino acids significantly increased the number of embryos and green plants obtained. The mean number of green plants per 100 anthers for the two genotypes in this experiment, HY320 and B723, went from 28.2 without amino acids in the medium, to 46.7 with addition of amino acids. Our second experiment with the genotypes HY320, Wim and Laval-19 showed that liquid medium with Ficoll is more efficient for anther culture (9.9 green plants/100 anthers) than solid (0 green plants), gelatinous media (2.5 green plants/100 anthers) or liquid medium with Membrane Rafts (0 green plants; Hoechst Celanese Corp.). Our third experiment revealed that the effect of replacement of sucrose by maltose varied with the genotype of the donor plant. Maltose partially inhibited the androgenesis of three responsive genotypes, HY320, Wim and Reliance (40.3 green plants/100 anthers instead of 43.9 with sucrose), while maltose significantly increased the androgenesis of the recalcitrant genotype Laval-19 (10.8 green plants/100 anthers instead of 5.4 with sucrose). An amino acid x maltose interaction was also observed. Amino acids without maltose increased androgenesis, but the addition of maltose to the amino acid-enriched medium eliminated this positive effect of the amino acids.

. 1998. Hybrid necrosis as a barrier to gene transfer in hexaploid winter wheat × × triticale crosses. Can. J. Plant Sci. 78: 239-244. An interspecific wheat × triticale hybridization program was initiated with the scope of widening and improving the winter wheat gene pool. However, progress was hampered by severe necrosis that caused the death of F 1 hybrids from crosses between the most winterhardy wheat and triticale cultivars. This paper describes hybrid necrosis as the main barrier to gene transfer between winter wheat cultivars Borden, Augusta and Ruby, and hexaploid winter triticales OAC Wintri and K9-6. Crosses with tester lines revealed that the three winter wheats were carriers of the necrotic Ne2 allele. High temperature (30°C) treatment until heading stage permitted to only partially circumvent the problem. A study of cross direction effects at the backcross level showed that the conventional method (F 1 × wheat) was more efficient for plant recovery, but plants produced by the alternative backcross system (wheat × F 1 ) were more self-fertile. Within the most winterhardy germplasm, hybrid necrosis is a major problem for transferring genes between winter wheat and triticale. The use of non-necrotic winter wheat lines such as MC11N, a local winter wheat selection, may have a special value as a bridge to circumvent the necrosis problem. jusqu'à l'épiaison n'a permis de contourner le problème que partiellement. Une étude de la direction du croisement au niveau du rétrocroisement a montré que la méthode conventionnelle (F 1 × blé) était plus efficace pour la récupération de plantes, mais que les plantes produites par la méthode alternative (blé × F 1 ) étaient plus auto-fertiles. Parmi le germoplasme le plus rustique, la nécrose hybride est un problème important pour le transfert de gènes entre le blé et le triticale d'hiver. L'utilisation de lignées de blé d'hiver non nécrosantes comme MC11N, une sélection locale de blé d'hiver, pourrait être utile comme pont pour contourner le problème de nécrose.