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United States Department of Agriculture

Agricultural Research Service

Research Project: SUNFLOWER GERMPLASM DIVERSIFICATION AND CHARACTERIZATION UTILIZING WILD SUNFLOWER SPECIES, CYTOGENETICS, AND APPLIED GENOMICS

Location: Sunflower Research

Title: Genetic compensation abilities of Aegilops speltoides chromosomes for homoeologous B-genome chromosomes of polyploid wheat in disomic S(B) chromosome substitution lines

Authors
item Friebe, Bernd -
item Qi, Lili
item Liu, Cheng -
item Gill, Bikram -

Submitted to: Cytogenetics and Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 24, 2011
Publication Date: May 5, 2011
Repository URL: http://naldc.nal.usda.gov/catalog/49695
Citation: Friebe, B., Qi, L.L., Liu, C., Gill, B.S. 2011. Genetic compensation abilities of Aegilops speltoides chromosomes for homoeologous B-genome chromosomes of polyploid wheat in disomic S(B) chromosome substitution lines. Cytogenetics and Genome Research. 134:144-150.

Interpretive Summary: Polyploidy is recognized as a common phenomenon in the evolution of plants. Common wheat (Triticum aestivum; 2n = 42, AABBDD) is an allohexaploid with three different subgenomes, A, B, and D. Both A and D genomes trace their origins to self-pollinating diploids T. urartu Thum. ex Gand. and Aegilops tauschii Coss., respectively. Although the donor species of the B genome is uncertain, Ae. speltoides has been considered as the most closely related donor species for the B genomes of polyploid wheat. However, little work has been reported on the genetic relationships of the S-genome chromosome with the B-genome chromosomes of polyploid wheat. Here we report the isolation of a set of disomic substitutions (DS) of S-genome chromosomes for the B-genome chromosomes, in which a pair of S-genome chromosomes substitute for a pair of B-genome chromosomes, and their effects on production of male and female gametes and plant development. Ae. speltoides chromosomes were identified by their distinct C-banding and fluorescence in situ hybridization patterns with the Ae. speltoides-derived clone pGc1R-1. Although no large structural differences between the S-genome and B-genome chromosomes exist, significant differences in gametophytic compensation were observed for chromosomes 1S, 3S, 5S and 6S. Similarly substitutions for 1S, 2S, 4S, 5S, and 6S affected certain aspects of sporophytic development in relation to spike morphology, fertility, and meiotic pairing. The substitution 5S(5B) had disturbed meiosis with univalents (plants with one unpaired chromosome) and multivalents (plants with three or more chromosomes pairing together) and suffered chromosome elimination in the germ tissues leading to heads of wheat with one set of chromosomes (haploids) in 50% of the plants. The effect of Ph1 gene on meiosis is well known, these results provide evidence for the role of the Ph1 gene in the maintenance of polyploid genome integrity. These and other the data are discussed in relation to the structural and functional differentiation of S and B genome chromosomes and the practical utility of the stocks in wheat improvement.

Technical Abstract: The S genome of Aegilops speltoides is closely related to the B and G genomes of polyploid wheats. However, little work has been reported on the genetic relationships between the S-genome and B-genome chromosomes of polyploid wheat. Here we report the isolation of a set of disomic substitutions (DS) of S-genome chromosomes for the B-genome chromosomes and their effects on gametophytic and sporophytic development. Ae. speltoides chromosomes were identified by their distinct C-banding and fluorescence in situ hybridization patterns with the Ae. speltoides-derived clone pGc1R-1. Although no large structural differences between S-genome and B-genome chromosomes exist, significant differences in gametophytic compensation were observed for chromosomes 1S, 3S, 5S and 6S. Similarly, substitutions for 1S, 2S, 4S, 5S and 6S affected certain aspects of sporophytic development in relation to spike morphology, fertility and meiotic pairing. The DS5S(5B) had disturbed meiosis with univalents/multivalents and suffered chromosome elimination in the germ tissues leading to haploid spikes in 50% of the plants. The effect of the Ph1 gene on meiosis is well known, and these results provide evidence for the role of Ph1 gene in the maintenance of polyploid genome integrity. These and other data are discussed in relation to the structural and functional differentiation of S- and B- genome chromosomes and the practical utility of the stocks in wheat improvement.

Last Modified: 4/16/2014
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