Gérard Doussinault

Study of wheat phylogeny by coRI analysis of chloroplastic and mitochondrial DNAs

Summary Electrophoregrams of DNA fragments obtained after EcoRI specific cleavage of chloroplastic (cp) and mitochondrial (mt) DNAs isolated from diploid, tetraploid and hexaploid wheat species are compared. HexaploidTriticum aestivum, tetraploidsT. turgidum andT. timopheevi and diploidAegilops speltoides appear to be characterized by an identical chloroplastic genome and can be differentiated from diploidsT. monococcum andAe. squarrosa. Considering the mitochondrial genome,T. aestivum andT. turgidum are similar, butT. timopheevi, T. monococcum, Ae. squarossa andAe. speltoides present a distinct diagram each. Consequently, the B genome of wheat cannot have originated from contemporaryAe. speltoides.

Location of Pm3g, a powdery mildew resistance allele in wheat, by using a monosomic analysis and by identifying associated molecular markers

A segregating population of doubled-haploid lines issued from the cross between the wheat (Triticum aestivum L. em. Thell) cultivars Courtot, resistant to several isolates of powdery mildew (Blumeria graminis DC. f. sp. tritici Em. Marchal), and Chinese Spring (susceptible) was used to map Mlar, a gene carried by Courtot and conferring resistance to this pathogen. The assignation of Mlar using monosomic lines of Courtot was confirmed by the mapping analysis. Mlar was located on the short arm of the chromosome 1A, in the vicinity of the locus XGli-A5 coding for storage proteins. This result was in accordance with those demonstrating that Mlar was an allele of the Pm3 locus (Pm3g), a gene also involved in the resistance to powdery mildew.

Wheat ( Triticum aestivum ): In Vitro Production and Utilization of Doubled Haploids

The literature ofthe last 15 years on hexaploid wheat (Triticum aestivum L. Thell. em.) on in vitro techniques and more precisely on anther culture, has been discussed in four chapters of a second Volume of this Series (Bajaj and Gosal 1986; Kudirka et al. 1986; Hu Han 1986; de Buyser and Henry 1986). There has been tremendous progress in haploid production by anther culture since the first wheat pollen plants were produced simultaneously in China by Ouyang et al., and in France by Picard and de Buyser in 1973. For example, special lines used in Chinese programs such as Ciano, Orofen, and Huapei no. 1, are now currently yielding very high rates of embryos and regenerated plantlets. Ouyang et al. (1983) reported % EMB (percentage of embryos related to the number of cultivated anthers) reaching 120% and % GRPL (percentage of green plantlets related to the total cultivated anthers) to be as high as 10–70%. Using European genetic material, likewise, the results in % GRPL sometimes reached 2–10% as was the case for a F9 line B described by Henry and de Buyser (1985), or for the cross Highbury-5B Chinese SpringxSicco-5B Chinese Spring reported by Snape et al. (1986). In most cases, however, the European wheat material gave rather lower frequencies of DH lines with an average yield of 0.05% to 0.1 % GRPL. Important progress remains to be made in the understanding of the genetic and physiological components of the phenomenon in order to increase the efficiency of anther culture in this cereal.

Analysis of the level of eyespot resistance due to genes transferred to wheat from Aegilops ventricosa

SummaryThe variety Roazon possesses genes for resistance to eyespot including that on the 7D chromosome transferred from Aegilops ventricosa. In order to assess the level of resistance due to the latter, we developed the intervarietal substitution for the 7D chromosome of ‘Roazon’ into ‘Courtot’ which is very susceptible to eyespot. As ‘Roazon’ contains Aegilops ventricosa cytoplasm, the substitution lines were produced both with wheat and Aegilops cytoplasm. Resistance was assessed at the seedling and the adult plant stage. No cytoplasmic effect was observed. The substitution lines were as resistant as ‘Roazon’. This shows that the chromosome 7D genes for resistance introduced from Aegilops ventricosa result in a high level of resistance in wheat.