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Wheat Information Service
Number 87: 1-4 (1998)
Research article

The chromosomal distribution of crossability genes in durum wheat cv. Langdon

Liu Deng-Cai, Yen Chi, Yang Jun-Liang, Lan Xiu-Jin, Peng Zheng-Song and Zheng You-Liang

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


Summary

We crossed the 14 D-genorne disomic substitutions of durum wheat cv. Langdon with an inbred rye and obtained a large variation in crossability percentages in the 1995-1996 and 1996-1997 growing seasons. The results showed that chromosomes 2A, 2B, 3B and 5B of Langdon carry crossability genes, while chromosomes 4B, 5A, 6A and 7A are involved in a suppressing effect on crossability with rye. Of which, chromosomes 2B and 3B showed a stronger effect on crossability than chromosome 5B, and chromosomes 4B and 7A showed a stronger effect than chromosome 5A. Thus, it was indicated that the tetraploid wheat cv. Langdon has a different kr system regulating crossability with rye in comparison with that of hexaploid common wheat.

Key words: Tetraploid wheat, crossability, inheritance


Introduction

The crossability of hexaploid common wheat with rye has been clearly shown to be controlled by four loci, designated kr1, kr2 (Lein 1943), kr3 (Krolow 1970) and kr4 (Luo et al. 1989), Iocated on chromosome 5B, 5A (Riley and Chapman 1967), 5D (Krolow 1970) and IA (Zheng et al. 1992), respectively. Dominant alleles of these crossability genes reduce crossability. The effect of kr1 is the greatest and the effect of kr4 gene is stronger than kr2 but weaker than kr1, while the effect of kr3 is very weak.Also,Miller et al.(1983) reported that chromosomes 3A and 3B carry genes affecting crossability.

Though as hexaploid wheat, tetraploid wheat has the kr system regulating crossability with rye (Krolow 1970), the evolution relationship of kr system between tetraploid wheat and hexaploid wheat is still an outstanding issue because data on the inheritance of crossability with rye in tetraploid wheat are quite rare.

Genc et al. (1996) crossed the 14 D-genome disomic substitutions of durum wheat cv. Langdon with rye and found that except 3D(3A) and 4D(4A), each of the remainder 12 substitutions showed a significant variation in crossability according to the control (Langdon), of which the 7D(7A) Iine showed the highest crossability and the 2D(2B) showed the lowest. They suggested the variation in crossability involved in the remainder 8 chromosolnes, except 1A, 3B, 5A and 5B, was probably caused by the heterozygosity present in the open pollinate rye parent, a Turkish landrace. However, an alternative explanation could be that the variation may have been caused by genes regulating crossability on the 8 chromosomes of Langdon. If the latter explanation is true, it will be indicated that there has a different kr system between tetraploid wheat cv. Langdon and hexaploid common wheat. Therefore, it is important that further studies to elucidate the effect of each of the 14 substitutions on the crossability with an inbred rye, rather than an open pollinate rye.


Materials and methods

A set of 14 disomic substitution lines in durum wheat cv. Langdon (Triticum turgidum ssp. turgidum conv. durum), in which each of A and B genome chromosome pairs of tetraploid wheat cultivar Langdon was replaced by a homoeologous pair from the D-genome of Chinese Spring, were pollinated with an inbred Chinese rye (Secale cereale L. cv. Qinling), used as male parent.

The emasculation and pollination techniques were the same as the previous paper (Liu et al. 1998). The number of florets with and without seeds for each spike was counted 25 days after pollination in the 1995-1996 season and 15 days after pollination in the 1996-1997 season. Crossability percentages were estimated as the ratio of the number of seed-set to number of florets pollinated. The t-test was adopted to detect the crossability differences between a substitution line and the control (Langdon).

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