Molecular and cytogenetic characterization of a common wheat-Agropyron cristatum chromosome translocation conferring resistance to leaf rust

Abstract

Crested wheatgrass (Agropyron cristatum L. Gaertn.) is a perennial species of economic importance as forage that also displays potentially valuable traits for wheat improvement trough intergeneric hybridization. In order to incorporate resistance genes from A. cristatum against wheat leaf rust (Puccinia triticina Erikss.) into common wheat (Triticum aestivum L.) a breeding programme was carried out by crossing and backcrossing the self-fertile amphiploid AABBDDPP (2n = 8x = 56) with T. aestivum (2n = 6x = 42; AABBDD). The AABBDDPP amphiploid was previously obtained by crossing tetraploid wheat (Triticum turgidum L. conv. durum Desf. 2n = 4x = 28; AABB) with a self-fertile allotetraploid (2n = 4x = 28; DDPP) between diploid wheat (Aegilops tauschii Coss.) and crested wheatgrass (A. cristatum). After three backcrosses a fertile stable line (named TH4) was obtained with 42 chromosomes. The fluorescence in situ hybridization and GISH analysis confirmed that TH4 carries a compensating robertsonian translocation involving the long arm of wheat chromosome 1B and the short arm of an unidentified A. cristatum chromosome. Specific molecular markers from A. cristatum also demonstrated the presence of chromatin from this species in the TH4 line. Macroscopic and microscopic observations indicated that the A. cristatum fragment that has been transferred to common wheat contributed a substantial level of partial resistance to leaf rust. The A. cristatum translocation line in bread wheat makes the disease resistance gene(s) from A. cristatum accessible for wheat breeding programmes.

Characterization of wheat – Psathyrostachys huashanica small segment translocation line with enhanced kernels per spike and stripe rust resistance

“…Similar spontaneous chromosomal rearrangements have also been reported in wheat-rye and wheat-A. cristatum translocation line (Ren et al 1991;Ochoa et al 2015).…”

“…The conventional chromosomal manipulation by crossing between common wheat and the amphiploid carrying alien desirable genes is an effective method to induce chromosome translocation (Jiang et al 1994;Friebe et al 1996;Qi et al 2007). The amphiploids between wheat and species from genera Secale, Thinopyrum, Agropyron, Dasypyrum, Leymus and Psathyrostachys have been synthesized to produce many translocation genotypes in wheat breeding (Jiang et al 1994;Lukaszewski 1995;Qi et al 2007;Kang 2011;Ochoa et al 2015;). However, it has been a challenge to transfer a small amount of alien chromatin containing the gene of interest from one genome to another non-homologous genome (Niu et al 2011).…”

Dissecting the Complex Genome of Crested Wheatgrass by Chromosome Flow Sorting

“…Numerous genes providing tolerance to biotic stress (i.e., resistance to barley yellow dwarf virus, wheat streak mosaic virus, yellow rust, leaf rust, stem rust, and powdery mildew) and abiotic stresses (i.e., cold‐, salinity‐ and drought tolerance) as well as genes improving yield were identified in crested wheatgrass (Shukle et al, 1987; Brettell et al, 1988; Littlejohn, 1988; Whelan, 1988; Friebe et al, 1992; Luan et al, 2010; Song et al, 2013; Ceoloni et al, 2015; Ochoa et al, 2015). In the present study, we extended the chromosome‐based approach to the complex P‐genome of crested wheatgrass (Said et al, 2018a) to produce genomic resources for chromosome‐mediated gene transfer into wheat.…”

“…As the wild‐crop relatives have not been subjected to human selection, they exhibit large genetic variation and offer a rich source of alleles and genes for crop improvement (Tanksley and McCouch, 1997). Alien gene transfer through chromosome engineering is an effective strategy to exploit this wild genetic diversity for wheat improvement (Feuillet et al, 2008; Luan et al, 2010; Molnár‐Láng et al, 2015; Ochoa et al, 2015; Zhang et al, 2017).…”

A high-density genetic map for P genome of Agropyron Gaertn. based on specific-locus amplified fragment sequencing (SLAF-seq)

“…For example, the disomic addition line 4844 shows superior numbers of florets and kernels per spike, and the alien chromosomes were designated as 6P of A. cristatum (Wu et al 2006). Recently an A. cristatumwheat compensating Robertsonian translocation conferring resistance to leaf rust was reported (Ochoa et al 2015). The detection of alien chromosome/fragment/gene in the wheat background can provide a guide to utilize the wheat-A.…”