Recovery of 2R.2Sk Triticale-Aegilops kotschyi Robertsonian Chromosome Translocations

Abstract

Robertsonian translocations (RobTs) in the progeny of triticale (×Triticosecale Wittmack) plants with monosomic substitution of Aegilops kotschyi chromosome 2S k (2R) were investigated by fluorescence in-situ hybridization. Chromosome 2S k of Ae. kotschyi is reported to possess many valuable loci, such as Lr54 + Yr37 leaf and stripe (yellow) rust resistance genes. We used a standard procedure to produce RobTs, which consisted of self-pollination of monosomic triticale plants, carrying 2R and 2S k chromosomes in monosomic condition. This approach did not result in RobTs. Simultaneously, we succeeded in producing 11 plants carrying 2R.2S k compensatory RobTs using an alternative approach that utilized ditelosomic lines of triticale carrying 2RS (short arm) and 2RL (long arm) telosomic chromosomes. Identification of molecular markers linked to Lr54 + Yr37 genes in the translocation plants confirmed that these resources can be exploited in current triticale breeding programmes.Agronomy 2019, 9, 646 2 of 12 from wild relatives into the wheat genetic background [10]. Recently, several attempts were made to transfer rust resistance genes from Aegilops, Agropyron and Triticum species into triticale [11][12][13][14][15].Aegilops species are closely related to wheat (and triticale, per se) and carry a number of valuable traits, which have been effectively incorporated into wheat by developing wheat-Aegilops hybrids and deriving addition, substitution and translocation lines [16]. Aegilops kotschyi Boiss. (2n = 4x = 28 chromosomes, U-and S-genomes) is a wild tetraploid goatgrass native to Northern Africa, the Mid-East, and Western Asia. Ae. kotschyi germplasm is exploited in wheat breeding [17] as a source of high grain protein, iron and zinc [18]. Moreover, Antonov and Marais [19] observed leaf rust resistance that was effective against the infection of Puccinia triticina in Ae. kotschyi. Marais et al. [20] identified the Lr54 and Yr37 leaf rust and stripe rust resistance genes, and developed aT2DS.2S k L wheat-Ae. kotschyi translocation line. The first Lr54 + Yr37 marker was developed by Heyns et al. [21]. Moreover, translocation gene sequences were cloned and specific SSR markers were developed [22].Homoeologous recombination based engineering is the most common way for efficiently utilizing the wild relative gene pool for crop improvement [23]. The generation of translocation lines is the most promising pathway for the exploitation of alien germplasm in crop breeding [23]. In distant hybrids, unpaired chromosomes are present as univalents during meiosis. Monosomic chromosomes are prone to centric breaks at anaphase I of meiosis, which misdivide and the broken ends fuse during the interkinesis of meiosis II [24][25][26]. Fusion of the misdivided products may result in the formation of a Robertsonian translocation (RobT) [27].Several steps are required to generate RobTs (Figure 1a), with self-pollination of double-monosomic plants being the most common method used in the induction of RobTs [26]. Wheat breeders can use a l...

Molecular Identification of Triticale Introgression Lines Carrying Leaf Rust Resistance Genes Transferred From Aegilops Kotschyi Boiss. and Ae. Tauschii Coss.

“…All 100 Bogo-2D t .2R plants showed different locations of chromosome breakpoints (Fig. 2a) compared to compensating Robertsonian translocations, which were reported in the parental forms (Ulaszewski et al 2019;Kwiatek et al 2018). Induced reduction of introgressed whole arms of alien chromosomes was reported multiple times (Howell et al, 2014;Lukaszewski, 2000;2010).…”

Molecular identification of triticale introgression lines carrying leaf rust resistance genes transferred from Aegilops kotschyi Boiss. and Ae. tauschii Coss

“…All 100 Bogo-2D t .2R plants showed different locations of chromosome breakpoints (Fig. 3) compared with compensating Robertsonian translocations, which were reported in the parental forms (Ulaszewski et al 2019;Kwiatek et al 2018). Induced reduction of introgressed whole arms of alien chromosomes was reported multiple times (Howell et al 2014;Lukaszewski 2000;2010).…”

“…kotschyi chromosome 2S k L arm with 2DS arm of wheat. Ulaszewski et al (2019) produced Robertsonian translocations (RobTs) in the progeny of triticale cv. Sekundo plants with monosomic substitution of Ae.…”

“…tauschii and Ae. kotschyi, respectively(Kwiatek et al 2018;Ulaszewski et al 2019) (Fig.1). Offspring plants of triticale translocation lines were used for marker-assisted selection of plants carrying Lr39 and Lr54 leaf rust resistance genes.…”

Chromosome Manipulation for Plant Breeding Purposes

“…In triticale (×Triticosecale Wittmack) new pathogens have evolved, moving from wheat and rye into triticale due to the increment of the harvested area. A screening of robertsonian translocations in the progeny of triticale lines carrying monosomic substitutions of Aegiops kotschyi chromosome 2S k (2R) was carried out using in situ hybridisation [4]. Plants carrying the robertsonian translocation were also checked using molecular markers for the presence of the Lr54 and Yr37 leaf rust and stripe rust resistance genes.…”