| Summary: | Dwarf cogongrass (Imperata cylindrica L.) was developed as a dwarf mutant
through heavy-ion beam irradiation 7 years ago. The dwarf mutant could be
expected to use as a new variety for a cover plant with low maintenance,
although it has poor seed fertility. To establish an efficient nursery production
system for dwarf cogongrass, we attempted mass propagation of it in liquid
culture and investigated the genetic stability of its regenerants. Multiple-shoot
clumps (MSCs) were initiated from apical meristems of dwarf cogongrass on
Murashige and Skoog (MS) solid medium supplemented with 0.1 mg L
�1 2,4-
dichlorophenoxyacetic acid (2,4-D) and 2.0 mg L
�1 benzylaminopurine (BAP).
Mass propagation conditions were established from MSCs cultured in MS
liquid medium containing 0.05 mg L
�1 2,4-D and 0.5 mg L
�1 BAP. The fresh
weight of the MSCs per flask increased by more than 16 times in 14 days of
liquid culture. Two different sizes of MSCs were produced in liquid culture.
When smaller MSCs (<2 mm in diameter) were transferred to half-strength
hormone-free MS solid medium, plant regeneration occurred at high frequency
(93.3%). These tissues showed high regenerative potential with approximately
350 green shoots recovered within 50 days from 60 regenerating clumps. Furthermore,
root elongation was vigorous in the regenerants growing in the same
medium. Regenerated plants were acclimatized in hydrated Jiffy-7 pellets for
30 days and then grown in soil as nursery plants. The plant height of regenerants
was almost the same as original dwarf cogongrass and significantly lower
than the wild type plants (P < 0.01). Analysis of amplified fragment length
polymorphism (AFLP) banding patterns generated using 10 primer combinations
showed no major genetic variations among the regenerated plants and
original dwarf cogongrass.
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