| Wheat Information Service Number 69: 1- 4 (1989) New hybrids between wheat and Agropyron. IV. Transmission of telo and whole chromosomes, and fertility of alien addition lines of Agropyron trachycaulum and A. cilliare in wheat1 H. C. Sharma Department of Agronomy, Purdue University, West Lafayette, IN 47907, U.S.A. Introduction Earlier attempts to hybridize Agropyron trachycaulum (Link) Malte (2n=28, SSHH), and A. ciliare (Trin.) Franch (2n=28, SSYY) with wheat were unsuccessful (Smith 1942). Intergeneric hybrids of Triticum aestivum L. with these species were reported and described for the first time by Sharma and Gill (1983a). In these crosses, wheat was used as the male parent, and embryo rescue was required. A. trachycaulum (female) x T. aestivum cv. Chinese Spring (CS), and A. ciliare (female) x CS hybrids were advanced to BC3 stage using CS pollen (Sharma and Gill 1983b). Transmission of the alien chromosomes and telosomes through pollen, and fertility of the alien addition lines are reported in this communication. Materials and Methods Two monosomic addition plants, t2-1-3 and t2-1-4, of A. trachycaulum x CS cross, both having 2n=43, and two plants, c3-1-4 and c3-1-2, of A. ciliare x CS cross, having 2n=44 and 46, respectively, were used in the present study. From the selfed progenies (BC3F2) of the monosomic additions, t2-1-3 and t2-1-4, plants having a chromosome number 42+t' or 43 were used to pollinate CS to isolate euplasmic alien addition lines. Similarly, from the selfed progenies of c3-1-2 and c3-1-4, plants having a chromosome number 42+t' or 43 were used to pollinate CS. The transmission rate of both telo and whole chromosomes through the male gametes was estimated by examining the chromosome composition of the hybrid seedlings. The fertility of the hybrids was measured by the total number of seeds set on each plant. Results and Discussion The chromosome composition of the BC3F2 plants used as pollen source to cross with CS, and the chromosome number and frequency of hybrid progenies are given in Table 1. A total of 4 plants from each of the two intergeneric derivatives were used as pollen source, and 35 and 36 hybrid plants, respectively, were analyzed cytologically (Table 1). The Agropyron chromosome involved in t2-1-3 was median. The Agropyron chromosomes involved in t2-1-4 an c3-1-4 were submedian (Sharma and Gill 1983b). The Agropyron chromosome in t2-1-4 has now been identified as 1Ht(B.S. Gill, pers. commun.). The rate of transmission of the sub-median A. trachycaulum chromosome through pollen was 10% compared to 20% transmission of telo of the same chromosome (Table 1). The transmission of telosome from the median A. trachycaulum chromosome was 45%. There was no transmission of the whole chromosome derived from c3-1-2. The transmission of the sub-median chromosome from c3-1-4 was 11.1% (Table 1). In the sample studied, the telo transmission from c3-1-4 was 10%. Thus, whereas the rate of transmission of sub-median chromosomes of A. trachycaulum and A. ciliare was alike, the rate of transmission of telosome of A. trachycaulum appeared to be higher than that of A. ciliare. Also, the rate of telosome is higher than that of the whole chromosome of A. trachycaulum. When a decaploid A. elongatum chromosome 6 was added to the hexaploid wheat complement, it was transmitted through the pollen with a reduced frequency (13.9%). However, a telocentric for the same chromosome was transmitted with the expected frequency (Knott 1964). Pollen carrying the added chromosome was at a competitive disadvantage, but the telocentric chromosome was not deleterious to the pollen. |
| 1: Contribution No.12242, Purdue Univ. Agric. Exp. Stn., W. Lafayette, Indiana 47901. I thank Dr. B.S. Gill for sharing the seed and for comments, and Drs. R. Shukle and C. Johns for review. |
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