A Database for Triticeae and Avena
IV. 7 Coordinator's report: Chromosome 7.
George Fedak, Ottawa Research Station, Central Experimental Farm, Ottawa, Ontario, K1A OC6, Ottawa, Canada.
Several more genes have been shown to be associated with chromosome 7. Kasha (1977) reported that f6 chlorina is not located on chromosome 6 as previously reported but should be placed near the centromere on chromosome 7. Karlsson (1977) studied the high lysine gene of Bomi Risø mutant 1508 (gene symbol not assigned) and noted that it was recessive, expressed a zenia effect and was probably located in the centromere region of chromosome 7. It was not linked to s or lys, the high lysine gene of Hiproly. Since a shrunken endosperm is associated with the high lysine content, Karlsson suggested that it could be a pletotropic effect of the high lysine gene.
The shrunken endosperm gene from Bomi Risø mutant 1508, designated sex3c was studied by Ullrich and Eslick (1977). The gene was recessive, expressed xenia and showing nearly complete linkage to msg 19 indicating that it was located in the centromere region of chromosome 7. The shrunken endosperm was associated with high lysine in mutant 1508 and both expressed xenia so that Ullrich and Eslick concluded that either these were two very closely linked genes or that one trait was a pleiotropic effect of the other.
Our efforts at establishing 3 point linkage stocks for chromosome 7 are continuing. Recently a telocentric for the short arm of chromosome 7 was obtained and most markers are being crossed to it plus the trisomic in an attempt to approximate the centromere position on that chromosome.
A "ditelo" for the short arm of chromosome 7 has been isolated and its cytogenetic behaviour is being studied.
References:
Karlsson, K.E. 1977. B.G.N. 7:40-41.
Kasha, K.J. 1977. B.G.N. 7:89-90.
Ullrich, S.F. and Eslick, R.F. 1977. B.G.N. 7:66-73.