Poster: Hormones

Abs # 608: Development of a Genetic Transformation and Regeneration System for Taro

Presenter:	He, Xiaoling , xiaoling@hawaii.edu
Authors	He, Xiaoling  (A)   Miyasaka, Susan C. (A)   Fitch, Maureen M. (B)   Zhu, Y. Judy (C)   Moore, Paul H. (B)
Affiliations:	(A): University of Hawaii (B): USDA, ARS - US Pacific Basin Agricultural Research Center (C): Hawaii Agricultural Research Center
Web Site:	http://www2.ctahr.hawaii.edu/ctahr2001/TPSS

Taro ( Colocasia esculenta ) is an important staple crop in the Pacific Islands. To improve the resistance of taro to fungal pathogens, a genetic transformation and regeneration system for taro has been developed. Highly regenerative taro calli of cv. Bun Long were obtained in a Murashige and Skoog (MS) medium with 2 mg L^-1 benzyladenine (BA) and 1 mg L^-1 napthaleneacetic acid (NAA). Alternating between MS with 2 mg L^-1 BA plus 1 mg L^-1 NAA and MS with 4mg L^-1 BA every two weeks induced shoot regeneration from callus. The rice chitinase gene, CHI11, was introduced into taro calli using high-velocity particle bombardment with the plasmid, pBI121. The candidate transformant calli were screened by polymerase chain reaction (PCR) amplification using a primer for the CHI11 gene and three positive lines were obtained, a transformation efficiency rate of 1%. Transformation of calli were conducted using the Agrobacterium tumefaciens strain, EHA105, and the plasmid, pCNL65. The plasmid carried the reporter gene, ß-glucoronidase (GUS) driven by the cauliflower mosaic virus (CaMV) 35S promoter. After 1 week of selection on antibiotic plates, 80 calli samples showed a strong blue color upon exposure to 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide, or a transformation efficiency rate of 90%. Also, transformation of shoots of cvs. Bun Long and Maui Lehua were conducted using Agrobacterium strain EHA105. After 1 week of selection on antibiotic plates, approximately 50% of the shoot samples stained positive for GUS activity.