MICROPROPAGATION AND GERMPLASM CONSERVATION OF TARO : COLOCASIA ESCULENTA VAR. ESCULENTA
CHNG CHENG OON ROSEMARY
CHNG CHENG OON ROSEMARY
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Abstract
Axenic cultures of Colocasta esculenta var. esculenta were established from
corm axillary bud explants. The rate of successful initiation was 76 percent of total buds
cultured and plantlets with well-developed shoot and root systems were obtained after 4
weeks culture on Murashige and Skoog (MS) medium supplemented with 20 gr1 sucrose
and solidified with 2.4 gr1 gel rite. High frequency direct shoot regeneration was achieved
through enhanced axillary development from conn axillary buds and thin-section-culture
of in vitro corms on similar hormone-free medium. ln addition, rapid clonal
multiplication of up to 80 shoots per conn in 8 weeks was achieved through thin-section
-culture of tissue-cultured-taro corm on medium containing 50 > uM BA. Prolonged culture
on high BA media produced up to 120 shoots per culture at the end of 6 months without
further subculture. Regenerated shoots developed roots readily when transferred to
hormone-free medium. Plantlets were ready for potting in 4 weeks and yielded l00
percent successful acclimatization rate.
Calli were initiated in root and thin-section-culture of tissue-cultured corm
explants on media containing NAA or 2,4-D, incubated under light or dark conditions.
Nodular, yellow, root callus regenerated roots on hormone-free medium. Two types of
corm calli were obtained, yellow nodular callus from the periderm and translucent friable
callus !rom the central conn tissues. Nodular callus regenerated roots on hormone-free
medium but shoots and roots on medium with high BA or sucrose concentrations.
Friable callus ·regenerated into complete plantlets on hormone-free medium atop original
conn explant.
Almost 90 percent of shoot-tip cultures were effectively conserved for up to
12 months without further subculture on half-strength MS medium overlay with water
under low light intensity. Over time, all cultures produced roots and developed into
complete plantlets. The type of culture seal used had a significant effect on multiple or
single shoot formation, possibly due to the extent of gaseous exchange. Paraffin oil
overlay was found to be unsuitable and led to early culture necrosis. The presence of BA
did not enhance culture survival.
In vitro shoot-tip and developing bud explants were successfully encapsulated in
an alginate matrix and stored for more than 4 weeks at room temperature or refrigerated
at 5"C for 8 weeks with minimal loss of viability. Similarly, m vitro induced corms were
also effectively stored for 4 weeks at room temperature or 6 months at 5"C. Both
artificial seeds and 111 vitro corms without any culture medium are suitable for use in the
exchange of taro germplasm. They can be stored and transported via glass vials or small
containers and be planted directly into potting mix or transferred to fresh culture media
with minimal loss of regenerability.
The developed protocols can be employed for germplasm conservation, exchange
and mass propagation for cultivation.
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Date
1995
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