Variations of subtelomeric tandem repeats and rDNA on chromosome 1RS arms in the genus Secale and 1BL.1RS translocations

Abstract

Background The wheat-rye 1BL.1RS translocations have played an important role in common wheat breeding programs. Subtelomeric tandem repeats have been often used to investigate polymorphisms of 1RS arms, but further research about their organizations on the 1RS chromosome is needed. Results 162 1RS arms from a wild rye species (Secale strictum) and six cultivated rye accessions (Secale cereale L.) (81 plants), 102 1BL.1RS and one 1AL.1RS translocations were investigated using oligo probes Oligo-TaiI, Oligo-pSc119.2–1, Oligo-pTa71A-2, Oligo-pSc200 and Oligo-pSc250, which were derived from tandem repeats TaiI, pSc119.2, pTa71, pSc200 and pSc250, respectively. The variations of 1RS arms were revealed by signal intensity of probes Oligo-pSc119.2–1, Oligo-pTa71A-2, Oligo-pSc200 and Oligo-pSc250. Proliferation of rDNA sequences on the 1RS chromosomes was observed. According to the presence of probe signals, 34, 127 and 144 of the 162 1RS arms contained TaiI, pSc200 and pSc250, respectively, and all of them contained pSc119.2 and pTa71. Most of the 1RS arms in rye contained three kinds of subtelomeric tandem repeats, the combination of pSc119.2, pSc200 and pSc250 was most common, and only eight of them contained TaiI, pSc119.2, pSc200 and pSc250. All of the 1RS arms in 1BL.1RS and 1AL.1RS translocations contained pSc119.2, pTa71, pSc200 and pSc250, but the presence of the TaiI family was not observed. Conclusion New organizations of subtelomeric tandem repeats on 1RS were found, and they reflected new genetic variations of 1RS arms. These 1RS arms might contain abundant allelic diversity for agricultural traits. The narrow genetic base of 1RS arms in 1BL.1RS and 1AL.1RS translocations currently used in agriculture is seriously restricting their use in wheat breeding programs. This research has found new 1RS sources for the future restructuring of 1BL.1RS translocations. The allelic variations of these 1RS arms should be studied more intensely as they may enrich the genetic diversity of 1BL.1RS translocations.

Development of a Set of Wheat-Rye Derivative Lines from Hexaploid Triticale with Complex Chromosomal Rearrangements to Improve Disease Resistance, Agronomic and Quality Traits of Wheat

“…Oligo-3A1 exhibited three intact signals in the middle of chromosome 5RL [28]. Probe Oligo-TaiI was found to have specific hybridization to the 1RS terminal region by ND-FISH [29]. In the present study, we found that the new Oligo-D01-135 had distinct hybridization in the NOR region of 1RS (Figure 2b).…”

Variation in highly repetitive DNA composition in rye and wild relatives discovered by FISH

“…New organizations of subtelomeric tandem repeats on 1RS were found, and they reflec ted new genetic variations of 1RS arms [3]. These 1RS arms might contain abundant allelic diver sity for agricultural traits.…”

“…Thus, recombination in interspecific chromosome as sociations could be promoted with the aim of transferring desirable agronomic traits from re lated genetic donor species into crops [2]. Additionally, recombination operates at subtelo meres and, as it happens in rye and wheat, ho mologous recognition and pairing are more often correlated with the recombining regions than with the crossoverpoor regions [3].…”

First insight into the genomes of the Pulmonaria officinalis group (Boraginaceae) provided by repeatome analysis and comparative karyotyping

“…Both of them are present in high copy numbers of tandem organized repetitive units in the genomes, and very often provide species-speci c patterns on chromosomes [e.g. 27,47,48,49,50].…”