J Heredity 89(1)87-89 (1998)
Preferential Male Transmission of an Alien Chromosome in Wheat
J. Jiang and B. S. Gill

A telocentric chromosome 5HtL from Elymus trachycaulus (Link) Gould ex Shinners was transferred into common wheat (Triticum aestivum L.). This chromosome was assigned to the homoeologous group 5 of Triticeae species by restriction fragment length polymorphism (RFLP) analysis. Chromosome 5HtL was transmitted in 20% of the female gametes and 97% of the male gametes in the genetic background of wheat, although the expected transmission frequencies of 5HtL through female and male gametes are 25% and 0-5%, respectively. It is likely that a gene located on 5HtL promotes male gamete competition. We suggest that the long arms of homoeologous group 5 chromosomes in Triticeae species carry genes that affect their transmission through male gametes.

Genes from a number of wild species have been successfully transferred into cultivated wheat (Islam and Shepherd 1992; Jiang et al. 1994a). Production of wheat-alien chromosome addition lines is usually the first step to do such transfers. One common character for most of the wheat-alien monosomic addition lines (42 wheat chromosomes plus one alien chromosome) is the low transmission of the alien chromosome through pollen, often less than 5%. Thus pollen with the additional alien chromosome can hardly compete with normal ones in fertilization. During the past few years we have isolated several wheat-Elymus trachycaulus (2n = 4x = 28, genomically StStHtHt) chromosome addition lines (Jiang et al. 1994b; Morris et al. 1990). In the selfed progenies of a monotelosomic 5HtL addition line, the telocentric chromosome 5HtL was detected almost exclusively in all the plants analyzed. This article reports on this rare case of preferential male transmission of 5HtL in the genetic background of wheat.