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Wheat Information Service
Number 86:13-18 (1998)
Research article

Chromosomal distribution of genes in diploid Lophopyrum elongatum (Host) A. Love that influences crossability of wheat with rye

 Liu Dengcai, Yen Chi, Yang Junliang and Zheng Youliang

Triticeae Research Institute, Sichuan Agricultural University, Dujiangyan City, 611830, Sichuan, China


Summary

Triticum aestivum L. lines with added or substituted chromosomes of Lophopyrum elongatum were hybridized with rye to identify chromosomes in L. elongatum that influenced crossability of wheat with rye. The results indicated that chromosome 4Ee, in L. elongatum suppressed crossability of wheat with rye. It was suggested that homoeologous chromosome distribution of crossability genes in L. elongatum was different from that of wheat.

Key words: Chromosome distribution, Crossability, Lophopyrum elongatum, Wheat


Introduction:

The study on the crossability of wheat with rye dates back to the work of Backhouse (1916). Lein (1943) and Riley and Chapman (1967) showed that alleles at Kr loci control crossability and that Kr1 and Kr2 are located on chromosome 5B and 5A, respectively. Krolow (1970) suggested that chromosome 5D also carries a gene Kr3 influencing crossability with rye. Luo et al. (1989) and Zheng et al. (1992) reported, besides the Kr1, Kr2 and Kr3 loci, a new gene, Kr4 located on chromosome 1A.

Dominant alleles of crossability genes in wheat, Kr1, Kr2, Kr3 and Kr4 are known to reduce crossability with rye (Riley and Chapman 1967; Krolow 1970; Zheng et al. 1992). The Kr loci also influences on the crossability of wheat with other species in the Triticeae (Snape et al. 1979; Falk and Kasha 1981; Thomas et al. 1980). There is a strong correlation between crossability with rye and other species in the Triticeae tribe.

Most European wheat varieties carry dominant Kr alleles and thus have very low crossability with rye (Zeven 1987). However, wheat landraces from China, Japan, East Siberia and Iran are rich in high crossability resources (Zeven 1987; Luo et al. 1994; Ma et al. 1996). It is known that Chinese Spring, a strain of a landrace in Sichuan province of China, has been selected as a standard cultivar in the genetic study of wheat primarily for its easy crossability with rye, which carries high crossability genes Kr1, Kr2, Kr3 . Some Chinese landraces of wheat were found that had even better crossability than Chinese Spring and possess a new crossability gene Kr4 (Luo et al. 1994).

Genetic variability for crossability occurs not only in wheat but also has been reported in alien species. Rye has a single dominant gene for crossability with wheat (Tanner and Falk 1981). Hordeum spontaneum carries a crossable genetic factor(s) similar to the Kr alleles in wheat (Snape et al. 1979; Taketa et al. 1995). Cheng (1997) found the crossability of octoploid triticale with common wheat was controlled by a pair of allelic genes. Moreover, genetic variability for crossability also exists in other species, such as Psathyrostachysjuncea, Thinopyrum trichophorum, etc. (Sharma 1995). However, which homoeologous chromosome(s) in these species influence(s) the crossability with wheat is still needed to be answered.

To advance the understanding of the evolution of genes that regulate crossability in wheat and its relatives in general, more information is needed about the presence and distribution of chromosomes influencing crossability in genomes of the diploid species. Lophopyrum is closely related to the genus Triticum and contains species that are the closest extant relative to the ancestors of Trilicum (Dvorak et al. 1984). The seven chromosomes of Lophopyrum elongatum (Host) Love (2n=2x=14, EeEe) show close genetic correspondence to the seven wheat homoeologous groups (Dvorak 1980). The objective of this study is to identify chromosomes in L. elongatum that influence crossability of wheat with rye.

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