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Wheat Information
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Number 72: 95-97 (1991)
Effect
of culture condition on plant regeneration capacity of mature embryo
derived callus in wheat (Triticum aestivum L.)
K. Kato, S. H. Chowdhury and S. Harada
Faculty of Agriculture, Kochi University, Nankoku 783, Japan
Immature embryo has so far been the best explant for efficient
regeneration of euploid plant in wheat. However it is required to
exploit another explant, because it is usually difficult to get
immature embryo throughout the year. In addition, the suitable stage
of immature embryo is strictly limited (Shimada and Yamada 1979).
This study was, therefore, attempted to establish an efficient
culture method of callus derived from mature embryo as an alternative
explant.
An Ethiopian local wheat cultivar 'IL 68' was used for embryo
culture. To kow the effect of pre-treatment with 2,4-D in the course
of embryo development, detached ears cultured after Kato et al (1990)
were dipped in 2,4-D solution (2mg/l) for 3 minutes. This treatment
was conducted at one of the seven developmental stages, that is, 8,
11, 14, 17, 20, 23 and 26 days after anthesis. Then treated car was
again cultured on liquid medium until their maturation. After
ripening, caryopses were harvested and used for culture as well as
control caryopses harvested from non-treated detached ear and from
intact ear of field grown plant. These seeds were first soaked in
hormone solution at 5C for 3 hours. The solution contained MS
inorganic salts, 30g/l sucrose and 2mg/l 2,4-D, combined with or
without 1mg/l BAP as described by Sasakuma and Tei (1989). After seed
sterilization, excised embryos were placed on agar medium with the
scutellum uppermost. The medium contained MS inorganic salts, 30g/l
sucrose and 8g/l agar, supplemented with 2,4-D and BAP as shown in
Table
1. Callus
induction and maintenance were conducted under a 26C and contiunous
light (1500-2000 lux) regime.
Callus induction rate was not different between the two cultures,
being 83.3% in culture No.1 and 85.7% in culture No.3. It was also
independent of the pre-treatment stage during detached ear culture.
In culture No.1 and No.2, shoot bud appeared frequently at green spot
region after 90 days of culture (Fig.
1). On the other
hand, in culture No.3, it appeared after 130 days of culture. This
result indicated that BAP added to pre-soaking medium and to callus
induction medium enhanced the speed of shoot differentiation.
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