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For the most part, molecular markers and detection of quantitative trait loci have been developed for forest tree species in view to performing marker-assisted selection (MAS). However, MAS has not been applied to forest trees until now. In parallel, some success stories of MAS in crop breeding have been reported. Recently, genotyping techniques have undergone a tremendous increase in throughput, moving the trend from MAS to genomic selection. We analyzed 250 papers reporting the use of MAS in plant breeding and found that the most popular schemes used were gene pyramiding and marker-assisted backcross manipulating a single or very few genomic regions which have a major impact on crop value. We reviewed theoretical and simulation studies to identify the parametric space in which MAS is expected to bring about significant advantages over phenotypic selection. Then, we tried to explain why MAS has not been applied to forest trees and discuss the opportunities offered by recent advances in these species. [ABSTRACT FROM AUTHOR]

With 2 figures and 3 tables RE714 is a winter wheat breeding line obtained from two interspecific crosses [( Aegilops tauschii no. 33/ Triticum dicoccum no. 119) and VPM = ( Aegilops ventricosa no. 10/ T. persicum)///Marne]. RE714 expresses powdery mildew resistance at the seedling, vernalized and adult stages. The origin of the main genetic factors involved in RE714 powdery mildew resistance ( Pm4b, QPm.inra-5D, QPm.inra-6A2, QPm.inra-7A3a and QPm.inra-7A3b) was studied by comparing alleles of RE714 and those of seven of its parental lines with 36 microsatellite markers previously detected as linked to these factors. VPM, and among its parental lines, the T. persicum accession, were identified as the donor of Pm4b to RE714. Aegilops tauschii no. 33 and T. dicoccum no. 119 were identified as the donors of QPm.inra-5D and QPm.inra-6A2 to RE714, respectively. Beauchamp, a line used at the end of the breeding scheme that created RE714, might be the donor of the favourable alleles of RE714 at quantitative trait loci on linkage group 7A3. These results are discussed in the context of introgression of valuable genetic factors from related species of the primary gene pool into wheat. [ABSTRACT FROM AUTHOR]

Powdery mildew is one of the major diseases of wheat in regions with a maritime or semi-continental climate which can strongly affect grain yield. The objective of the study was to identify and compare quantitative resistance to powdery mildew of line RE9001 at the adult plant and vernalized seedling stages. RE9001 has no known Pm gene and shows a high level of adult plant resistance in the field. Using 104 recombinant inbred lines (RILs) of an RE9001 × ‘Courtot’ F8 population, a genetic map was developed with 363 markers distributed over 26 linkage groups and covering 3825 cM. The global map density was 1 locus/10.3 cM. RILs were assessed under field and tunnel greenhouse conditions for 2 years in two locations. Eleven quantitative trait loci (QTL) were detected at the adult stage and they explained 63% of the variation, depending on the environment. Three QTLs were found, at least, in the two environments. One QTL from RE9001, mapped on chromosome 2B, was stable in each environment. This QTL, QPm.inra.2B, explained 10.3–36.6% of the variation and could be mapped in the vicinity of the Pm6 gene. At the vernalized seedling stage, one QTL detected by the isolate 93-27 could be an allele of the Pm3g gene present in ‘Courtot’. No residual effect of the Pm3g gene was detected at either stage. Markers flanking the QTL 2B could be useful tools to combine resistance to powdery mildew in wheat cultivars. [ABSTRACT FROM AUTHOR]

Abstract The homozygosity of spontaneous hexaploid plants derived from anther culture was evaluated in wheat and triticale by means of 18 and 22 microsatellite markers, respectively. Most of the spontaneous hexaploid plants were homozygous for all the loci tested and had chromosomes recombining for parental alleles. Only 12% of the spontaneous hexaploid wheat plants, 11% of the artificially doubled wheat plants and 4.4% of the spontaneous hexaploid triticale plants were heterozygous at one to three of the loci studied. This showed that spontaneous hexaploid plants mostly came from normal haploid cells, obtained after meiosis, that underwent spontaneous chromosome doubling. However, first or second division restitution, producing unreduced gametes, cannot be completely excluded to explain the origin of the spontaneous hexaploid plants. Cytomixis, involving only one chromosome, or development of aneuploid trisomic gametes, followed by chromosome doubling for the spontaneous hexaploid plants, or transposition events could also explain some of the results obtained. [ABSTRACT FROM AUTHOR]

Abstract Moderate resistance to eyespot was first incorporated in the variety Cappelle-Desprez (CD). Later the gene Pch1 , which could confer a higher level of resistance, was introduced from Aegilops ventricosa . However Pch1 -carrying varieties can sustain significant eyespot-induced yield losses in severe attack situations. A strategy to further enhance the resistance of wheat is by pyramiding Pch1 and the genes for resistance in CD. The first requirement to achieve this is a better understanding of the genetics of resistance in CD. The resistance of the 21 Cappelle-Desprez (Bezostaya) disomic substitution lines was evaluated. Chromosome 7A was confirmed as carrying a major gene for resistance to eyespot at the seedling stage. However, this study demonstrates that this chromosome has no effects at the adult stage. Chromosome 5A was shown to carry a major gene for resistance to eyespot at the adult stage, which was stably expressed each year of testing. Chromosomes 1A and 2B had significant effects for only two years among four. [ABSTRACT FROM AUTHOR]