BGN 12: Telotrisomic analysis of three genes with newly obtained telotrisomic, Triplo 3S, in barley BARLEY GENETICS NEWSLETTER, VOL. 12, II. RESEARCH NOTES
Singh et al., pp. 42-44

II. 17. Telotrisomic analysis of three genes with newly obtained telotrisomic, Triplo 3S, in barley. (1)

R. J. Singh, A. Shahla and T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U.S.A.

(1) Supported by USDA/SEA Competitive Research Grant 5901-0410-9-0334-0 and USDA/SEA Cooperative Research Grant 12-14-5001-265 and CSU Hatch Project.

The first telocentric chromosome for chromosome 3 (Tsuchiya, 1971a) was designated as telo 3A (Tsuchiya, 1971b). Telocentric chromosome 3A was later identified as the long arm of chromosome 3 (telo 3L) based on the morphological similarity of telotrisomic 3A (Triplo 3A) to its primary trisomic (Triplo 3, Pale)(Tsuchiya and Singh, 1973). However, telotrisomic analysis of many genes which were previously located in the short arm of chromosome 3 (3S) by Robertson (1971) showed that these genes segregated in the trisomic fashion (Singh and Tsuchiya, 1974; Tsuchiya and Singh, 1982). Based on these results, telo 3A was redesignated as telo 3S (Singh and Tsuchiya, 1974, 1977, 1981c; Tsuchiya, 1974, 1980; Tsuchiya and Singh, 1982). However, recent results from Giemsa banding karyotype analysis (Singh and Tsuchiya, 1982a) clearly showed that telocentric chromosome 3A was actually the long arm (3L) (Singh and Tsuchiya, 1981b, 1982b).

Recently a new telocentric chromosome was obtained in chromosome 3 (Singh and Tsuchiya, 1981a; Tsuchiya et al. 1982), and identified as the short arm of chromosome 3 (3S) by Giemsa banding technique (Singh, 1981; Singh and Tsuchiya, 1981, 1982a,b).

In this note the results of telotrisomic analysis of three genes with the newly obtained telotrisomic for 3S (Triplo 3S) are reported. Three genes used in this experiment are as follows:

BGS  uz    uzu or semi-brachytic, recessive    BGS 0102
BGS  al     albino lemma, recessive                 BGS 0108
BGS  ac    albino seedling, recessive               BGS 0106

Analysis of uz: The gene uz was previously located on chromosome 3 (Robertson, 1971). By telotrisomic analysis this gene was associated with a specific arm of chromosome 3 (Tsuchiya and Singh, 1982). Further tests have been conducted to obtain the definite association of uz with one arm of chromosome 3. The segregation ratios were observed in the F2 generation (Table 1).

Table 1. Segregation ratios in F2 generation from crosses between telotrisomic 3S and three marker genes.

The segregation ratios in diploid, telotrisomic and total population fit to disomic 3:1 ratios and an appreciable number of recessive homozygotes were found in trisomic portion. This clearly indicates that the gene uz is not located in the short arm of chromosome 3 but located in the long arm (3L). This is in agreement with recent results (Singh and Tsuchiya, 1982b; Tsuchiya, 1981).

Analysis of al: The gene al has also been associated with chromosome 3 (Robertson, 1971). It was later studied by means of telotrisomic analysis and was located in the presumed short arm (3S)* of chromosome 3 (Tsuchiya and Singh, 1982) [* This identification was changed to 3L (long arm) by Singh and Tsuchiya 1982, TAG. (In press)]. In this study the gene al was studied by telotrisomic analysis with Triplo 3S. As shown in Table 1, the segregation ratios in the F2 generation did not fit a 3:1 disomic ratio and no recessive homozygotes were found in the trisomic portion. This result confirms the association of al with the short arm of chromosome 3 (3S).

Analysis of ac: The gene ac has been reported to be located in the short arm of chromosome 3 with the following linkage data (Robertson, 1963):

The telotrisomic analysis of this gene with the new Triplo 3S showed disomic 3:1 segregation ratios in the total population as well as diploid and trisomic portions with an appreciable number of homozygous recessives the telotrisomic portion. These results clearly indicated that the gene ac is not associated with the telocentric chromosome (3S) used in this experlment but is located in the opposite arm (3L), or the segment carrying ac in the 3S is deficient.

References:

Robertson, D. W. 1963. Barley Genetics I (Proc. 1st Intern. Barley Genet. Symp.):159-180.

Robertson, D. W. 1971. Barley Genetics II (Proc. IInd Intern. Barley Genetics Symp.):220-242.

Singh, R. J. 1981. BGN 11:84-85.

Singh, R. J. and T. Tsuchiya. 1974. BGN 4:66-69.

Singh, R. J. and T. Tsuchiya. 1977. Z. Pflanzenzuchtg 78:327-340.

Singh, R. J. and T. Tsuchiya. 1981a. BGN 11:69.

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