II.44 Possible occurrence of telocentric chromosome 5S.
T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U,S.A,
During the study of chromosomes in F2 population from the cross Triplo 5L x g-Ms-h/g-ms-h (Tsuchiya, 1976 ), one plant was found which had apparently shorter extra telocentric chromosome than the normal telocentric 5L in the parental line and all other siblings in the F2 population. The plant was separately planted in a pot and the morphological characteristics were observed with the following results:
Morphologically the suspected Triplo 5S is quite different from Triplo 5L, showing almost normal characteristics. It is known that an extra short arm has less or almost no effect on the morphology of a telotrisomic plant compared to a telotrisomic plant for the long arm of the same chromosome (Tsuchiya, 1972; Singh, 1974). The new telotrisomic fulfills this expectation if the telocentric chromosome is proved to be 5S. However, another possibility can not be ruled out that the apparent 5S could be 5L with a deficiency, or it may be a telocentric chromosome for other than chromosome 5.
The "univalent shift" in telotrisomic barley (1S to 1L) has been reported (Tsuchiya, 1971). If this new telocentric chromosome is proved to be telo 5S, this will be the second case of the univalent shift in telotrisomics in barley (5L to 5S). Cytological identification by Giemsa banding technique and genetic analysis with several marker genes are now under way.
References:
Singh, R.J. 1974. Cytogenetics of telotrisomics in barley. Ph.D. Thesis, Colorado State University, Mimeo., 112 pp.
Tsuchiya, T. 1971. "Univalent shift" in telotrisomic barley. BGN, 1: 63-64.
Tsuchiya, T. 1972. Cytogenetics of telotrisomics in barley. BGN, 2: 93-98.
Tsuchiya, T. 1976. Telotrisomic analysis of a multiple genetic marker stock (g-Ms-h/g-ms-h) in chromosome 5. BGN 6:82-84.
