A Database for Triticeae and Avena
II. 7. Cytoplasmic male sterility in barley. XIII. Nuclear genes
for restoration of msm2 cytoplasm.
H. Ahokas, Department of Genetics, University of Helsinki, P. Rautatiekatu
13, 00100 Helsinki 10, Finland. "R"
The recently found cytoplasmic male sterility msm2 differs from
msml by its higher sensitivity to partially restoring genotypes
(Ahokas 1982). The Rmfla restorer gene of Sel. 77-1 (Ahokas 1979) completely
restored the fertility in msm2 (Ahokas 1982). Evidence is presented below
that 13 of the complete restorer genes of msml are also effective
in msm2 cytoplasm.
Cv. Adorra-like derivatives with msml cytoplasm and heterozygous
for a single dominant restorer gene were used as the pollen parent to a
male sterile Adorra-like derivative of msm2 cytoplasm. About 15
F1 plants of each cross were raised to reveal the segregation of male sterility/fertility.
The results are listed in Table 1. It appears that all the crosses except
for that with Rfm,,l fit to a l:l ratio. All the crosses, however,
gave male fertile segregants with the Adorra-like nuclear background which
maintains sterility. Therefore, these 13 restorer genes must be capable
of restoring in msm2 cytoplasm.
Rfmlb, Rfmlc, and Rfmld of PI 296856, PI 296919, and PI 284755, respectively,
are evidently allelic with Rfmla (Ahokas 1980), and therefore most likely
restorers of msm2, too. The accessions PI 296853 and 79BS15-B, carriers
of genes Rfm,,m and Rfm,,r, respectively (Ahokas 1980, 1981), were found
to be restorers in msm2 (Ahokas 1982).
Table 1. Fl segregations of 13 restorer genes in msm2 cytoplasm.
The crosses have an Adorra-like nuclear gene background.
PI 296897 is an F1 restorer both in msml and msm2 (Ahokas,
unpublished). This accession of the collection of Israeli spontaneum
barleys is a carrier of an exceptional 'triplicate' electromorph banding
pattern of Est4 locus (Kahler and Allard 1981, Kahler et al. 1981).
Electrophoretic zone of a single Est4 gene appears in double bands. The
double banded phenotype could be explained by the existence of the enzyme
in two cell organelles, e.g. in cytosol and plastids or mitochondria, either
of the two enzyme forms being specifically processed to be revealed with
the electrophoretic technique. A protein or an enzyme coded by nuclear
gene and appearing in a maternally inherited organelle might be associated
with restoration of maternal sterility. Rfmla gene is not associated with
any triplicate electromorph pattern of Est4 zone at the seedling state
studied (Ahokas, unpublished). It will be seen later, if the triplicate
Est4 form of PI 296897 is somehow associated with the restoration of that
accession. PI 296897 originates from the Judean Foothills region. The spontaneum
barley populations of this region of Israel have a high (about 10x) frequency
of complete restorers (Ahokas 1981). Therefore, the occurrence of triplicate
Est4 and restoration in PI 296897 would more probably be a coincidence.
Ahokas, H. 1979. Cytoplasmic male sterility in barley. Acta Agric. Scand.
Ahokas, H. 1980. Cytoplasmic male sterility in barley. VII. Nuclear
genes for restoration. Theor. Appl. Genet. 57:193-202.
Ahokas, H. 1981. Idem. X. Distribution of m fertility restoration ability
in the wild progenitor of barley in Israel. Ann. Bot. Fenn. 18:313-320.
Ahokas, H. 1982. Idem. XI. The msm2 cytoplasm. Submitted.
Kahler, A. L. and R. W. Allard. 1981. Worldwide patterns of genetic
variation among four esterase loci in barley (Hordeum vulgare L.). Theor.
Appl. Genet. 59:101-111.
Kahler, A. L., M. I. Morris and R. W. Allard. (1981) Gene triplication
and fixed heterozygosity in diploid wild barley (Hordeum spontaneum). J.
Hered. (In press)
BGN 12 toc
BGN Main Index