Development and molecular characterization of wheat-Aegilops kotschyi addition and substitution lines with high grain protein, iron, and zinc

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 [...]