Cytological analysis of hybrids among triticales and trigopiros

Maia Fradkin,Ezequiel Grassi,María Rosa Ferrari,Lidia Poggio,Eduardo Greizerstein,Héctor Paccapelo,Víctor Ferreira

doi:10.1590/s1415-47572009005000070

Maia Fradkin, Ezequiel Grassi + Show 5 more

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https://doi.org/10.1590/s1415-47572009005000070

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Abstract

We studied three different tricepiros: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F1 was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F 3 individuals. In all F 8 tricepiros (Don Santiago x Don Noé), F 12 tricepiros (Cumé x Horovitz) and F 12 tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids.

Highlights

Polyploidy has played an important role in plant speciation
Tricepiro (Don Santiago x Don Noé): The F1 hybrid was obtained at the Universidad Nacional de La Pampa, Province of La Pampa, Argentina, by crossing triticale Don Santiago INTA with trigopiro Don Noé INTA
It is expected that the bivalents correspond to homologous pairing between chromosomes belonging to wheat A and B genomes, whereas the 21 univalents could be chromosomes of D (Triticum aestivum), R (Secale cereale) and J (Thinophyrum ponticum) genomes

Summary

Introduction

Polyploidy has played an important role in plant speciation. It has been estimated that perhaps more than 70% of Angiosperms have undergone polyploidy one or more times at some point in their evolutionary history (Ma and Gustafson, 2005). An example of a particular case of the harmonic coexistence of several genomes achieved by chromosomal rearrangement and gain or loss of chromosomes or even completed genomes, was observed in the tricepiro Don René INTA (Ferrari et al, 2005). This cultivar was obtained by crossing a hexaploid triticale (2n = 42, AABBRR, A, B from wheat and R from rye) with an octoploid trigopiro (2n = 8x = 56, AABBDDJJ, with A, B, D from wheat and J from wheatgrass), and became stable at 2n = 42. In situ hybridization techniques (GISH and FISH) have demonstrated that the genomic constitution of this allopolyploid is AABBRR with introgression of Thinopyrum (J genome) in chromosome pair 6 of the wheat A genome (Ferrari et al, 2005)

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