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Over two billion people, depending largely on staple foods, suffer from deficiencies in protein and some micronutrients such as iron and zinc. Among various approaches to overcome protein and micronutrient deficiencies, biofortification through a combination of conventional and molecular breeding methods is the most feasible, cheapest, and sustainable approach. An interspecific cross was made between the wheat cultivar 'Chinese Spring' and Aegilops kotschyi Boiss. accession 396, which has a threefold higher grain iron and zinc concentrations and about 33% higher protein concentration than wheat cultivars. Recurrent backcrossing and selection for the micronutrient content was performed at each generation. Thirteen derivatives with high grain iron and zinc concentrations and contents, ash and ash micronutrients, and protein were analyzed for alien introgression. Morphological markers, high molecular weight glutenin subunit profiles, anchored wheat microsatellite markers, and GISH showed that addition and substitution of homoeologous groups 1, 2, and 7 chromosomes of Ae. kotschyi possess gene(s) for high grain micronutrients. The addition of 1U/1S had high molecular weight glutenin subunits with higher molecular weight than those of wheat, and the addition of 2S in most of the derivatives also enhanced grain protein content by over 20%. Low grain protein content in a derivative with a 2S-wheat translocation, waxy leaves, and absence of the gdm148 marker strongly suggests that the gene for higher grain protein content on chromosome 2S is orthologous to the grain protein QTL on the short arm of group 2 chromosomes. Key words: wheat, Aegilops kotschyi, grain iron, grain zinc, grain protein, microsatellite markers, HMW-glutenin subunits, genomic in situ hybridization. Plus de deux milliards de personnes qui se nourrissent principalement d'aliments de base souffrent de deficiences en proteines et certains micronutriments comme le fer et le zinc. Parmi diverses approches visant a palier ces deficiences en proteines et en micronutriments, la biofortification via une combinaison de methodes moleculaires et conventionnelles d' amelioration genetique constitue l'approche la plus realisable, economique et durable. Un croisement interspecifique a ete realise entre le ble 'Chinese Spring' et l'accession 396 de l'Aegilops kotschyi, dont les grains ont une teneur en fer et en zinc trois fois plus elevee et une teneur en proteine superieure de 33 % a la concentration rencontree chez les cultivars de ble. Des retrocroisements ont ete realises a repetition avec selection pour le contenu en micronutriments a chaque generation. Treize lignees derivees avec une forte teneur en zinc et en fer ont ete analysees pour la teneur en cendres et la concentration en zinc, fer et proteines dans les cendres. Des marqueurs morphologiques, le profil des glutenines HMW, des marqueurs microsatellites d ancrage et des analyses GISH ont revele l'addition et la substitution d homeologues des groupes 1, 2 et 7 de l'Ae. kotschyi, lesquels porteraient un ou des genes conferant une plus haute teneur en micronutriments chez les grains. L'addition 1U/1S se traduisait par des glutenines HMW de plus grande taille que chez le ble tandis que l'addition du chromosome 2S entrainait chez la majorite des lignees un accroissement de plus de 20% de la teneur en proteines. La faible teneur en proteine chez une lignee portant une translocation 2S-ble, la caractere cireux des feuilles et l'absence du marqueur gdm148 suggerent fortement que le gene qui confere une plus haute teneur en proteine sur 2S serait l'orthologue du QTL pour la teneur en proteine des grains qui est situe sur le bras courte des chromosomes du groupe 2. Mots-cles : ble, Aegilops kotschyi, teneur en fer des grains, teneur en zinc des grains, teneur ne proteine des grains, marqueurs microsatellites, sous-unites HMW des glutenines, hybridation genomique in situ. [Traduit par la Redaction], Introduction More than half of the world's population suffers from iron and zinc deficiencies and more than 160 million children under the age of five lack adequate protein intake (WHO [...]

Synthetic amphiploids are the immortal sources for studies on crop evolution, genome dissection, and introgression of useful variability from related species. Cytological analysis of synthetic decaploid wheat (Triticum aestivum L.)-- Aegilops kotschyi Boiss. amphiploids (AABBDD[U.sup.k][U.sup.k][S.sup.k][S.sup.k]) showed some univalents from the [C.sub.1] generation onward followed by chromosome elimination. Most of the univalents came to metaphase I plate after the reductional division of paired chromosomes and underwent equational division leading to their elimination through laggards and micronuclei. Substantial variation in the chromosome number of pollen mother cells from different tillers, spikelets, and anthers of some plants also indicated somatic chromosome elimination. Genomic in situ hybridization, fluorescence in situ hybridization, and simple sequence repeat markers analysis of two amphiploids with reduced chromosomes indicated random chromosome elimination of various genomes with higher sensitivity of D followed by the [S.sup.k] and [U.sup.k] genomes to elimination, whereas 1D chromosome was preferentially eliminated in both the amphiploids investigated. One of the partial amphiploids, [C.sub.4] T. aestivum 'Chinese Spring' -Ae. kotschyi 396 (2n = 58), with 34 T. aestivum, 14 [U.sup.k], and 10 [S.sup.k] had stable meiosis and high fertility. The partial amphiploids with white glumes, bold seeds, and tough rachis with high grain macroand micronutrients and resistance to powdery mildew could be used for T. aestivum biofortification and transfer of powdery mildew resistance. Key words: Partial amphiploid, chromosome elimination, grain iron, grain zinc, powdery mildew resistance, in situ hybridization. Les amphiploides synthetiques constituent des ressources immortelles pour des etudes portant sur revolution des cultures, la dissection des genomes et l'introgression de variabilite utile provenant d'especes apparentees. Une analyse cytogeenetique d'amphiploides deecaploldes (Triticum aestivum L.)-- Aegilops kotschyi Boiss. (AABBDD[U.sup.k][U.sup.k][S.sup.k][S.sup.k]) a permis d'observer des univalents a compter de la generation [C.sub.1] suivie d'eelimination chromosomique. La plupart des univalents ont atteint la plaque de la metaphase I apres la division reductionnelle des chromosomes appariees et ont subi la division equationnelle qui a mene a leur elimination sous forme de chromosomes retardataires ou de micronoyaux. Une variation substantielle du nombre de chromosomes observes chez les microsporocytes provenant de diffeerents eepis, epillets et antheres chez certaines plantes suggere qu'il se produirait egalement de l'elimination chromosomique au niveau somatique. Des analyses GISH, FISH et de marqueurs SSR sur deux amphiploides avec un nombre reduit de chromosomes a indique que l'elimination chromosomique etait aleatoire au sein des diffeerents genomes. Globalement, le genome D, suivi des genomes [S.sup.k] et [U.sup.k],etait le plus souvent sujet a elimination et le chromosome 1D avait ete preferentiellement perdu chez les deux amphiploides examines. Un des amphiploides partiels de generation [C.sub.4], 'Chinese Spring'--Ae. kotschyi 396 (2n = 58), comptait 34 chromosomes du T. aestivum, 14 du genome [U.sup.k] et 10 du genome [S.sup.k] et il presentait une meeiose stable ainsi qu'une fecondite eeleveee. Les amphiploides partiels a glumes blanches, gros grains, rachis resistant, forte teneur en micro- et macronutriments ainsi que resistants a l'oidium pourraient s'aveerer utiles pour l'ameelioration de la valeur nutritive du T. aestivum et le transfert de resistance a l'oidium. Mots-cles: amphiploide partiel, elimination chromosomique, teneur en fer dans les grains, teneur en zinc dans les grains, resistance a l'oidium, hybridation in situ. [Traduit par la Redaction], Introduction Alloploidy through interspecific hybridization and spontaneous doubling of chromosomes has played a major role in speciation and genome evolution of higher plants (Slotis and Slotis 1999; Feldman and Levy [...]

Abstract: Four different interspecific hybrids involving three different accessions of Aegilops longissima Schweinf. & Muschl. with high grain iron and zinc content and three Triticum turgidum L. subsp. durum (Desf.) [...]

Genes transferred to crop plants from wild species are often associated with deleterious traits. Using molecular markers, we detected a cryptic introgression with a leaf rust resistance gene transferred from Aegilops triuncialis L. into common wheat (Triticum aestivum L.). One agronomically desirable rust-resistant introgression line was selected and advanced to [BC.sub.3][F.sub.11] from a cross of hexaploid wheat and A. triuncialis, n situ hybridization using A. triuncialis genomic DNA as a probe failed to detect the alien introgression. The translocation line was resistant to the most prevalent races of leaf rust in India and Kansas. Genetic mapping in a segregating [F.sub.2:3] population showed that the rust resistance was monogenically inherited. Homeologous group 2 restriction fragment length polymorphism markers XksuF11, XksuH16, and Xbg123 showed diagnostically polymorphic alleles between the resistant and susceptible bulks. The alien transfer originated from homeologous chromosome recombination. The A. triuncialis-specific alleles of XksuH16, XksuF11, Xbg123, and one simple sequence repeat marker Xcfd50 cosegregated with the rust resistance, suggesting that the wheat-A, triuncialis translocation occurred in the distal region of chromosome arm 2BL. This translocation was designated T2BS.2BL2tL(0.95). The unique source and map location of the introgression on chromosome 2B indicated that the leaf rust resistance gene is new and was designated Lr58.

Abstract Background The uneven distribution of recombination across the length of chromosomes results in inaccurate estimates of genetic to physical distances. In wheat (Triticum aestivum L.) chromosome 3B, it has been estimated that 90% of the cross over events occur in distal sub-telomeric regions representing 40% of the chromosome. Radiation hybrid (RH) mapping which does not rely on recombination is a strategy to map genomes and has been widely employed in animal species and more recently in some plants. RH maps have been proposed to provide i) higher and ii) more uniform resolution than genetic maps, and iii) to be independent of the distribution patterns observed for meiotic recombination. An in vivo RH panel was generated for mapping chromosome 3B of wheat in an attempt to provide a complete scaffold for this ~1 Gb segment of the genome and compare the resolution to previous genetic maps. Results A high density RH map with 541 marker loci anchored to chromosome 3B spanning a total distance of 1871.9 cR was generated. Detailed comparisons with a genetic map of similar quality confirmed that i) the overall resolution of the RH map was 10.5 fold higher and ii) six fold more uniform. A significant interaction (r = 0.879 at p = 0.01) was observed between the DNA repair mechanism and the distribution of crossing-over events. This observation could be explained by accepting the possibility that the DNA repair mechanism in somatic cells is affected by the chromatin state in a way similar to the effect that chromatin state has on recombination frequencies in gametic cells. Conclusions The RH data presented here support for the first time in vivo the hypothesis of non-casual interaction between recombination hot-spots and DNA repair. Further, two major hypotheses are presented on how chromatin compactness could affect the DNA repair mechanism. Since the initial RH application 37 years ago, we were able to show for the first time that the iii) third hypothesis of RH mapping might not be entirely correct.

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