| Theoretically an extra chromosome should be transmitted by 50% of the
gemetes on the female as well as on the male side. This assumption is seldom
realized (Simeone et al 1985). Transmission rate of extra chromosome through
male gamete varied from 0% in barley (Tsuchiya 1960) to 52% in maize (Einset
1943). Sears (1956) obtained only 1.3% disomics from selfing monosomic addition
of an Aegilops umbellulata chromosome to hexaploid wheat. In wheat-barley
crosses, Islam et al (1978) found that the transmission of barley chromosomes
was very low. Mochizuki (1963) recovered no disomic addition line from an
A. elongatum monosomic addition line to tetraploid wheat. The A.
intermedium chromosome conditioning stripe rust resistance in wheat
was transmitted through 10% of the male gametes, whereas the chromosome
imparting stem rust resistance had a selective advantage through the pollen
with transmission of 85-96% (Cauderon and Rhind 1976). Transmission rates
of A. trachycaulum and A. ciliare chromosomes studied here
lie within these limits. In the euplasmic condition the vigor and fertility of both euploids and those having alien telo were better than those having whole chromosome (Table 2, Fig. 1). Apparently the alien whole chromosomes of A. trachycaulum and A. ciliare had some negative effect. The seed number per plant was lower in plants involving A . ciliare than in plants involving A. trachycaulum. Even though all the plants appeared normal, comparisons showed that plants having 2n=42 were the most vigorus and those having 2n=43 were the least vigorous. Yield of most addition lines of A. intermedium in wheat was lower than the wheat parent (Cauderon and Rhind 1976). All ditelosomic additions except 3S, 4S, 4L of barley in wheat were less fertile than wheat parent (Islam 1983). References Cauderon Y and Rhind J (1976) The effect on wheat of an Agropyron chromosome carrying stripe rust resistance. Ann Amelior Plantes 26: 745-749 Einset J (1943) Chromosome length in relation to transmission frequency of maize trisomics. Genetics 28: 349- 364 Islam AKMR (1983) Ditelosomic additions of barley chromosomes to wheat. Proc 6th Int. Wheat Genet Symp, Kyoto, Japan pp. 233-238 Islam AKMR, Shepherd KW and Sparrow DHB (1978) Production and chracterization of wheatbarley addition lines. Proc 5th Int Wheat Genet Symp, New Delhi,India pp. 365-371 Knott DR (1964) The effect on wheat of an Agropyron chromosome carrying rust resistance. Can J Genet Cytol 6: 500-507 Mochizuki A (1963) Agropyron addition lines of durum wheat. Wheat Inf Serv 15-16: 50-53 Sears ER (1956) The transfer of leaf rust resistance from Aegilops umbellulata to wheat. Brookhaven Symp in Biol 9: 1-22 Sharma HC and Gill BS (1983a) New hybrids between Agropyron and wheat. 2. Production, morphology and cytogenetic analysis of F1 hybrids and backcross derivatives. Theor Appl Genet 66: 111-121 Sharma HC and Gill BS (1983b) New hybrids between Agropyron and wheat. 3. Backcross derivatives, effect of Agropyron cytoplasm, and production of addition lines. Proc 6th Int Wheat Genet Symp, Kyoto, Japan pp. 213-221 Simeone R, Blaco A and Giorgi B (1985) Chromosome transmission in primary trisomics of durum wheat. Cereal Res Commun 13: 27-31 Smith DC (1942) Intergeneric hybridization of certain cereals and other grasses. J. Agric. Res 64: 33-37 Tsuchiya T (1960) Cytogenetic studies of trisomics in barley. Jap J Bot 17: 177-213 |
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