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APPLICATIONOFSOMACLONALVARIATIONFORISOLATIONOFGENE

MUTATIONSCONTROLLINGSEXUALPLANTREPRODUCTION

L.A.Elkonin,N.Kh.Enaleeva, E.V.Belyaeva

Volga-Region Institute ofBiotechnology, 410020Saratov

Using the morphogenic callus lines of different sorghum genotypes as

a model we studied a possibility of obtaining mutants with gene or cytoplasmic

male sterility, male-fertile revertants, mei-mutants and genotypes with

elements of apomixis from tissue culture.

The calli obtained in different experiments from the leaves and panicles

o f a haploid produced the male-sterile mutants with a high frequency (66-

90% o f regenerants). The mutants appeared in the R0-R1 and manifested

unusual inheritance pattern: the mutation was inherited as nuclear recessive

in crosses with some fertility restorers o f the CMS A1, however, in many

cases the sterile plants were almost absent in the F2 or BC1-BC2; in crosses

with other CMS A1 restorers the mutation was expressed as dominant, but

the maternal inheritance of male sterility was observed in some backcross

progenies. Different independently arised mutants demonstrated sim ilar

inheritance pattern. The induced mutation was introduced by backcrossing

in three different agronomically valuable sorghum lines and sterile analogues

of these lines are used in hybrid breeding. The monogenic recessive mei-

mutants with complete sterility caused by significant abnormalities of the

chromosome synapsis during the meiotic prophase I were obtained from the

same cell lines of haploid origin after prolonged cultivation. A sim ilar

monogenic recessive mutation caused complete sterility was revealed in

the progeny of a single green regenerant obtained from the callus line of

diploid origin treated with streptomycine. Male sterility mutation observed in

this regenerant was gradually eliminated in the R2-R3 after pollination with

original line.

A line with a partial male fertility caused by mutation of nuclear fertility

restorer gene was obtained from a cell line derived from a plant with CMS.

Cyto-embryological analysis revealed the presence of additional enlarged

cells with one or several nuclei o r aposporous embryo-sacs (ESs) alongside

with the sexual ES in the ovules of this line. A fter subsequent selection the

frequency of aposporous structures increased up to 80%. The apomictic

proembryos were recorded in some plants with the frequency 4-6%.

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