Precise identification of wheat--Thinopyrum intermedium translocation chromosomes carrying resistance to wheat stripe rust in line Z4 and its derived progenies

The wheat--Thinopyrum intermedium derived line Z4 has displayed novel and effective stripe rust resistance for over 40 years. This study aimed to precisely identify the chromosome constitution of line Z4 and determine the stripe rust resistance contribution using multicolor fluorescent in situ hybridization (FISH) and molecular marker analysis. The results indicated that the Z4 line (2n = 44) contained two pairs of non-Robertsonian translocations without the 3A chromosomes of wheat. FISH karyotypes of [F.sub.3] progenies derived from crosses between Z4 and MY11 indicated that the transmission of the translocated chromosomes appeared normal and the number of wheat chromosomes 3A and 3D frequently varied. The FISH signal distribution of a new repetitive probe, named Oligo-3A1, confirmed the physical breakage points on chromosome 3AL incorporated into translocated chromosomes. PLUG markers revealed the breakage points on chromosomes 3A, 7[J.sup.S], and 3D invloved in the translocated chromosomes, and they were designated as T3DS-3AS.3AL-7[J.sup.S]S and T3AL-7[J.sup.S][S.7J.sup.S]L. Stripe rust resistances surveys indicated that the proximal region of 7[J.sup.S]S or 7[J.sup.S]L may confer the resistance at the adult plant stage. The precise characterization of the chromosome complements of wheat--Th. intermedium Z4 and derived progenies has demonstrated the importance of combining cytogenetic and molecular approaches in the genomics era for further wheat genetic manipulation and breeding purposes. Key words: Thinopyrum intermedium, wheat, rust resistance, chromosome translocation. La lignee Z4, derivee d'un hybride ble--Thinopyrum intermedium, presente une resistance nouvelle et efficace contre la rouille striee depuis plus de 40 ans. Cette etude visait a identifier precisement la constitution chromosomique de la lignee Z4 et de determiner la region chromosomique contribuant a la resistance a la rouille striee a l'aide de l'hybridation in situ a fluorescence (FISH) multicolore et de marqueurs moleculaires. Les resultats indiquent que la lignee Z4 (2n = 44) contient deux paires des translocations non-Robertsoniennes et qu'elle est depourvue des chromosomes 3A du ble. Les caryotypes FISH des progenitures [F.sub.3] derivees de croisements entre Z4 et MY11 indiquent que la transmission des translocations etait normale et que le nombre de chromosomes 3A et 3D variait frequemment. La distribution des signaux FISH d'une nouvelle sequence repetee, nommee Oligo-3A1, a confirme que les points de bris physiques sur le chromosome 3AL etaient incorpores au sein des translocations. Des marqueurs PLUG ont revele que des cassures sur les chromosomes 3A, 7[J.sup.S] et 3D etaient impliquees dans les translocations et celles-ci ont ete designees T3DS-3AS.3AL-7[J.sup.S]S et T3AL-7[J.sup.S][S.7J.sup.S]L. L'examen de la resistance a la rouille striee a suggere que la region proximale des chromosomes 7[J.sup.S]S ou 7[J.sup.S]L pourraient conferer la resistance a l'etat adulte. La caracterisation precise de la composition chromosomique de la lignee derivee Z4 (ble--Th. intermedium) et les progenitures derivees a demontre l'importance, en cette ere genomique, de combiner des approches cytogenetiques et moleculaires pour faire progresser l'ingenierie genetique et la selection chez le ble. [Traduit par la Redaction] Mots-cles : Thinopyrum intermedium, ble, resistance a la rouille, translocation chromosomique.
Introduction Stripe rust is one of the foliar diseases of common wheat, caused by Puccinia striiformis Eriks. f. sp. tritici (Pst) it can cause significant yield reductions in infected fields [...]