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Horticulture Digest

Date Last Edited:  08/24/2001


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Hawaii Cooperative Extension Service


Horticulture Digest #106
MERISTEM CULTURE OF WHITE TARO

Taro has the possibility of becoming an ingredient in hypoallergenic foods. It could be an allergen-free substitute for rice and wheat in staples such as bread, noodles, spaghetti, macaroni, gruel, taro rice, crackers, and dumplings. It is advantageous fo r infants with food allergies.

The internal color of the raw taro corm ranges from white, yellow and pink to a combination of colors. Upon heating, the color may be creamy white, grayish purple, bright yellow or a combination of colors depending on the cultivar. White-fleshed taro woul d not need any extra processing or bleaching to turn it into a product that mimics foods used worldwide--this would be a cost saving as well as a reduction of the chance of contamination during processing (Hollyer, 1991; Hollyer and Sato, 1990). Meristem culture can be important in propagating white taro and in the shipment of disease-free plant material.

Results:
Almost all explants regenerated shoots. Multiplication of shoots occurred with most of the explants. Subsequent contamination problems prevented the statistical determination of the best treatment. However, overall assessment of the data in Tables 1 and 2 reveals that modified Murashige and Skoog (MS) medium with 10 µM IAA and 5 µM BA promoted a higher mean number of shoots per explant for all cultivars.


Table 1. Mean number of shoots per explant of white taro (Colocasia esculenta var. esculenta cv. Pikokea, Pololu, Nihopuu and Haokea) cultured on Murashige and Skoog media with varying levels of IAA and BA.
                                        Number of
              ÁM IAA/	    Number      shoots per
Cultivar       ÁM BA    of explants     explants

'Pikokea'        0/0           1           1.0

                 5/5           9           9.3

                5/lO           6          12.0

                10/5          17          13.7

               10/10           6           7.3


'Pololu'         0/0           6           5.5

                 5/5           1           6.0

                5/10           4           4.5

                10/5           6           7.8

               10/10           1           3.0


'Nihopuu'        0/0           9           2.1

                 5/5           6           4.0

                5/10           9           5.2

                10/5          11          15.5

               10/10           6           3.7


'Haokea'         0/0           2           1.0

                 5/5           9           4.4

                5/10           8           2.5

                10/5           8           7.8

               10/10           8           4.1



Table 2. Overall mean number of shoots per explant of white taro (Colocasia esculenta var. esculenta cv. Pikokea, Pololu, Nihopuu and Haokea) per IAA and BA treatment.
                                  Number of
                      Number     shoots per
ÁM IAA/ÁM BA       of explants    explants

     0/0                l8           3.1

     5/5                25           6.2

    5/10                27           5.8

    10/5                42          12.2

   10/10                21           4.9



Experiment:
A problem encountered in tissue culture of taro is the disinfestation of the plant material coming straight from the field. Contamination of the cultures is high. A disinfestation method has been determined with good success (Martin et al., 1993). Cutting s, with a portion of the corm, of white taro (Colocasia esculenta var. esculenta cv. Pikokea, Pololu, Nihopuu, and Haokea) were taken directly from the field. The disinfestation method was a 60-minute rinse under running tap water, followed by a 40-minute soak in a lO% Clorox solution, and then a double rinse in sterile water (20 minutes for each sterile water rinse). Axillary and apical meristems within the petioles were excised and placed in sterile water. They were subsequently put in a 7 0% ethanol dip, followed by a sterile water rinse, a 30-minute soak in a 5% Clorox solution, and three further sterile water rinses.

Excised meristems were then placed, one ex-plant per test tube, on modified Murashige and Skoog (MS) media (Murashige and Skoog, 1962). Our basic modified MS medium omits glycine and kinetin. Also, 1 mg/liter thiamine, 1 mg/liter nicotinic acid, and 8.5 g/liter agar are different levels from MS medium. IAA levels were varied. Test tubes contained modified MS medium with growth regulators indole-3-acetic acid (IAA) and 6-benzyladenine (BA) in respective combinations of 5/5, 5/10, 10/5 and 10/10 µM. A treatment of no growth regulators was also included.


S.P. Martin,
C.A. Bobisud, and
T.T. Sekioka, terry@hawaii.edu


LITERATURE CITED

Hollyer, J. R. (ed.). 1991. Proceedings of: White taro; another opportunity: allergen-free products from Hawaii, University of Hawaii, Honolulu, Hawaii, 24 October 1990.

Hollyer, J. R. and D. M. Sato (eds.). 1990. Proceedings of: Taking taro into the 1990s: a taro conference, University of Hawaii, Hilo, Hawaii, 17 August 1989.

Martin, S. P., C. A. Bobisud, and T. T. Sekioka. 1993. Micropropagation of white taro (Colocasia esculenta var. esculenta cv. Pikokea, Pololu, Nihopuu, and Haukea). HortScience 28:543. (Abstr.)

Murashige, T. and F. Skoog. 1962. A revised medium for rapid growth and bioassays tobacco tissue cultures. Physiol. Plant. 15:473-497.


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