| Summary: | A higher level of efficiency in the production of doubled-haploids must be achieved if
this procedure is to be beneficial in plant improvement. Of equal importance is the
development of protocols, which are not genotypic specific and result in progeny that represent
a random sample of gametes from the parental lines.
To address these issues seven diverse winter wheat genotypes and a spring wheat,
previously shown to be responsive in haploid plant production from anther culture, represented
the experimental material. Two methods of generating haploid plants were employed. These
were anther culture and the intergeneric hybridization of wheat with maize. Three induction
media (MN6, P2 and Liang's) in liquid and semi-solid forms were employed with anther culture
a direct culture. A modified floret culture along with different concentrations (20 and 100 ppm)
and mode of application of 2,4-D were examined for the wheat x maize approach, Measurements
included callus and embryo production and haploid plantlet regeneration.
Two winter genotypes 'Gene' and 'Yamhill' did not respond to the anther culture
methodology. For responsive genotypes MN6 was superior to P2 and Liang's medium for the
traits measured. In contrast 'Chris' the spring wheat was more responsive for plantlet
regeneration on P2 medium. No differences in haploid plantlet regeneration for the traits were
observed between liquid and semi-solid medium forms.
For the wheat x maize approach, direct culture was superior to the modified floret culture
for embryo and haploid plantlet production. No differences were found in either 2,4-D
concentration or whether 2,4-D was applied through tiller injection or placed as droplets on the
florets.
The wheat x maize approach was superior to anther culture for both embryo and green
haploid plant production based on the number of florets used. Albino plants were produced in all
responsive genotypes with anther culture. In contrast, no albino plants were regenerated with the
wheat x maize approach. All genotypes were responsive for both embryo production and haploid
plant regeneration in the intercrossing approach. In addition no regeneration distortion was
observed for specific population employing this protocol.
The wheat x maize approach was superior to anther culture for embryo production. This
was also true for green haploid production based on the number of florets used. A higher
proportion of albino plants was also observed when anther culture was employed. A further
attribute of the wheat x maize approach was that all genotypes tested were responsive to embryo
and haploid production. It was also revealed that no segregation distortion was present in three
doubled haploid populations developed from wheat x maize crosses. === Graduation date: 1999
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