GrainGenes
A Database for Triticeae and Avena
Tsuchiya and Menkes, pp. 105-107
II.41. New karyotype in a genetic stock, Utah T3, for purple lemma and pericarp (Re 2).
T. Tsuchiya and Jennifer Menke. Department of Agronomy, Colorado State University, Fort Collins, Colorado 80521, U.S.A.
*Reports II.33. (p.80) through II.42. (p.108) by T. Tsuchiya and co-workers are based on the results of researches supported by NSF Research Grants GB4482X and GB30493 and Colorado State University Experiment Station Project (Hatch 8).
During the study of F1 hybrids between the telotrisomic for Triplo 2L and the genetic stock for purple lemma and pericarp (Re 2) in Utah T3, there was found a strange karyotype. Detailed karyotype analysis of both parents of the hybrid revealed that the Re 2 stock was homozygous for an abnormal chromosome condition.
In root tip mitosis of the Re 2 stock a normal chromosome 6 was not found. Instead a pair of large three-segmented chromosomes was found. In the diploid F1 hybrids between SE 16 and the Re 2 stock there was found a normal chromosome 6 and a three-segmented chromosome. Careful comparison of normal chromosome 6 and the abnormal chromosome revealed that the abnormal chromosome consisted of a long and short arm of chromosome 6 and an abnormally large satellite, as shown in Figure 1.
Based on these findings it is assumed that a translocation has occurred between the satellite of chromosome 6 and one arm of one of the four longest non-satellited chromosomes. F1 hybrids between Utah T3 and Shin Ebisu 16 showed a ring-of-four and five bivalents at diakinesis and metaphase I of meiosis. The quadrivalent was associated with nucleolus at diakinesis. Pollen fertility of F1 diploid hybrids between Shin Ebisu 16 and Re 2 stock was 71.1%. An attempt is being made to establish an Re 2 stock free from this chromosomal aberration.
This finding of spontaneous occurrence of reciprocal translocation in a genetic stock and the finding of possible case of radiation-induced paracentric inversion in the genetic stock for wst 3 in variety Akashinriki (Tsuchiya, 1972, BGN 2:lO4-lO5) suggests that there may be more cases of chromosomal abnormalities in genetic stocks. Actually, spontaneous inversions have been detected in the variety OAC 21 and some other varieties (Powell and Nilan, 1968). Radiation-induced chromosomal aberrations associated with gene mutations have also been reported; translocations associated with erectoides mutations (Hagberg, 1960), paracentric inversions associated with gemetic sterility (Holm, 1960) and a translocation associated with a male mutant (Tsuchiya, 1969, 1972).
From these findings, the following suggestions are made for barley geneticists:
(1) The fertility (pollen fertility and seed sets) of F1 hybrids should be studied in all crosses.
(2) If semisterility is found in F1, then meiosis of F1 hybrids should be critically studied.
(3) Karyotype study of both parental materials are also recommended for possible finding of detectable translocation shown in the case of genetic stock of Re 2 for purple lemma and pericarp, if F1 hybrid showed semi-sterility.
References:
Hagberg, A. 1960. Genet. Agr. 12:319-336.
Holm, G. Hereditas 46:274-278.
Powell, J. B, and R. A. Nilan. 1968. Crop Sci.
Tsuchiya, T. 1969. Induced mutations in Plants:573-590.
Tsuchiya, T, 1972, BGN 2:104-105.
Tsuchiya, T. 1972. BGN 2:107-108.