II. 42 Allelism evidence for barley high lysine, shrunken endosperm xenia (sex) mutants.
S.E. Ullrich and R.F. Eslick. Department of Plant and Soil Science, Montana State University, Bozeman, Montana 59717. "R"
Bomi Risø mutants 8, 13 and 1508 (the latter designated sex3 by Ullrich and Eslick, 1977) and Carlsberg II 29, 56 and 86 express a shrunken endosperm xenia trait as well as high lysine in our environments. Compana sex1, Bomi Risø 13 and 1508 (sex3) and Carlsberg II Risø 29 and 86 were intercrossed to determine allelism among the mutants for the associated shrunken endosperm xenia trait. The females for all crosses were genetic male steriles. Plump:shrunken classification of F2 seed on the F1 plants was the major criterion for the sex allelism test.
Risø 86 and Compana sex1 and Risø 86 and Risø 29 were the only mutant sources found to be allelic, as no plump seed were found on F1 plants (Table 1) or on F2 plants from these crosses. It is concluded that the sex traits of Risø 29 and 86 are allelic with sex1a Compana. This is consistent with trisomic analysis data (Ullrich and Eslick, 1978) which provided evidence for monofactoral recessive inheritance and the assignment of the sex traits of Risø 29 and 86 to chromosome 6. Jarvi and Eslick (1975) using translocation breakpoint linkage information assigned Compana sex1 to chromosome 6. We propose the sex traits of Risø 86 and 29 be designated sex1d and sex1e, respectively (Scheuring and Ramage, 1976, assigned sex2b to an sex mutant on Chromosome 7 that is in effect a zygotic lethal mutant).
The independent non-allelic genes in crosses with one another should segregate on F1 heads in a 9:7, plump:shrunken, seed ratio, while linked non-allelic gene segregation should approach a 1:1 ratio, assuming monofactorial recessive gene action for each mutant. Single recessive gene action has been demonstrated for Compana sex1, Risø 1508, 29 and 86 by the authors cited above and for Risø 13 by Doll (1976). Furthermore, Ullrich and Eslick (1978) provided evidence for the location of the sex trait of Risø 13 on chromosome 6 and Risø 1508 on chromosome 7. A 9:7 or 1:1 F2 seed progeny ratio was not found for some of the crosses. For these crosses, in general, a deficiency of plump seed was observed. There are inconsistancies among crosses, particularly these involving Risø 13. No definite conclusions can be drawn and more investigation is needed, but perhaps endosperm dosage effects and/or epistatic interactions between genes is indicated. Minor or modifier genes in the various genetic backgrounds represented may also be involved.
As a second approach twelve F1 seed from all but one cross were analyzed for lysine by a half kernel microbiological assay technique (Sands, Doll and Eslick, manuscript in preparation). Assuming that high lysine and shrunken endosperm are associated traits in the mutants under consideration (see Doll, 1976; Karlsson, 1977; and Ullrich and Eslick, 1977), the data in Table 2 generally support the sex allele test results. Assuming allelism, the F1 should be equal to, but not less than one or both parents. Assuming non-allelism, the F1 should be lower than one or both parents. In general over the range of crosses made, the F1's tend to be higher in lysine than expected. This as with the plump:shrunken endosperm ratios observed may indicate epistatic relationships between mutant genes.
We believe additional information is needed to definitely establish the gene action involved in some of these crosses.
References:
Doll, H. 1976. Genetic studies of high lysine barley mutants. pp. 542-546. In H. Gaul (ed.) Barley C-enetics III. Proc. 3rd Intl. Barley Genet. Symp. Verlag Karl Thiemig, Munich.
Jarvi, A.J. and R.F. Eslick. Shrunken endosperm mutants in barley. Crop Sci. 15:363-366.
Karlsson, K.E. 1977. Linkage studies in a gene for high lysine content in Risø barley mutant 1508. Barley Genet. Newsl.
Scheuring, J.F. and R.T. Ramage. 1976. A tertiary trisomic balanced for both msg2 and sex2. Barley Genet. Newsl. 6:60-62.
Ullrich, S.E. and R.F. Eslick. 1977. Inheritance of the shrunken endosperm character, sex3c, of Bomi, Risø Mutant 1508 and its association with lysine content. Barley Genet. Newsl. 7:66-73.
Ullrich, S.E. and R.F. Eslick. 1978. Chromosome location evidence for Risø induced high lysine, shrunken endosperm mutants of barley. Barley Genet. Newsl. 8:
