BGN 2: Barley chromosome 5 BARLEY GENETICS NEWSLETTER, VOL. 2, IV. REPORTS FROM COORDINATORS
Tuleen, pp. 133-135

IV 4. Barley chromosome 5.

N. A, Tuleen. Department of Soil and Crop Sciences, Texas A and M University, College Station, Texas 77843, U.S.A.

map

Loci located at centromere region: fs2, ert-b, int-a, cer-e, sh3, x5,x6 genes for short height in Compana (h,,g), golden color of Compana (yh2), ms4, ms20.

Genetic characters and symbols

The linear order of the genes trd-B-at was established by Ramage and Peterson (1960). This ordering was later confirmed by Takahashi et al. (1966). In addition Takahashi's data indicated that fs2 was located between the at and mla loci with recombination values of 29.2 + 1 for fs2 vs at and 39.2 + 2 for fs2 vs. mla. Fedak (1969) was able to associate the trd, at, sp,,b and rvl loci with the telocentric for chromosome 5, and concluded that the telocentric chromosome was short arm of chromosome 5 (5 S). Critical analysis of karyotype of telotrisomic plants (Telotri 5A) showed that the telocentric chromosome was the long arm of chromosome 5 (5L) (Tsuchiya, 1972). Based on linkage data from crosses with B and trd the genes eak and f7 have been placed distal to the trd locus. The ordering of the factors for mildew resistance in the short arm of chromosome 5 is based mainly on data obtained by Hiura (1960).

Linkage data for translocations vs. factors on chromosome 5 have been obtained by numerous workers. Since the recovery of cross-overs in interstitial segments is greatly reduced, genes located near the centromere show close linkage with all translocations involving that chromosome. Ramage and Lehman (1964) reported data from crosses of ms with 18 translocations involving chromosome 5. All of these translocations showed close linkage (none to 5%) with this gene. Persson (1969) reported similar results from crosses of ert-b with 17 translocations involving chromosome 5. The break points for the translocations T1-5a and T4-5e are located near the centromere of chromosome 5 and in the short and long arms respectively. The close linkage (less than 3%) of the genes int-a (Persson, 1969), cer-e (Fester and Sogaard, 1969), and x5 (Tuleen, unpublished) with the T1-5a and T4-5e breakpoints place these three genes in the centromere region. Data from balanced tertiary trisomics place the ms locus distal to the T4-5e break point (Tuleen, 1966). No recombination was observed in 176 diploid progeny from the cross of T1-5a x fs2 where complete classification for the translocation was made by root-tip squashes This gene should also be located near the centromere. Based on their close linkage with the ms locus, the genes ms4, ms20, yh2, h,,g, and x6 may also be in the centromere region. Takahashi and Yasuda (1969) reported that B and sh3 were linked with 36% recombination and the sh3 gene was found to be independent of trd. Since a recombination value of 36% was reported for B vs. fs2, the sh3 locus may also be located near the centromere.

Data from three point linkage tests, telosomics, and tertiary trisomics will be needed to determine the correct linear order of these genes located near the centromere.

Literature cited:

Fedak, G. 1969. The behavior and utility of some monotelotrisomics in Hordeum. Ph.D. thesis, University of Manitoba, Winnipeg, Canada.

Fester, T. and B. Sogaard. 1969. The localization of eceriferum loci in barley. Hereditas 61:327-337.

Hiura, U. 1960. Studies of the disease resistance of barley IV. Genetics of the resistance of powdery mildew. Ber. Ohara Inst. Landwirtsch. Biol. 11:235-300.

Persson, G. 1969. An attempt to find suitable genetic markers for dense ear loci in barley I. Hereditas 62:25-96. Ramage, R. T. and D. W. Peterson. 1960. Barley chromosome 5. Barley Newsletter 4:4. (Quoted by permission of the author)

Ramage, R. T and L. C. Lehman, 1964. Cytogenetic studies of barley. Barley Newsletter 8:8. (Quoted by permission of the author.)

Takahashi, R., J. Hayashi, and U. Hiura. 1966. Inheritance and linkage studies in barley III. Linkage studies of the gene fragile stem-2 and orientation of linkage map on barley chromosome 5. Ber. Ohara Inst. Landwirtsch. Biol. 13:199-212.

Takahashi, R. and S. Yasuda. 1970. Genetics of earliness and growth habit in barley. Barley Genetics II. (Proc 2nd International Barley Genetics Symposium. 1969):388-408

Tuleen, N. A, 1966. The use of tertiary trisomics for the orientation of linkage groups in barley. Barley Newsletter 10-66.

Tsuchiya, T. 1972. Karyotype analysis of telotrisomic type for the telocentric chromosome 5A (5L). BGN 2:89.

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