Full Length Research Paper

High frequency plant regeneration from mature seed-derived callus of Italian ryegrass (Lolium multiflorum) cultivars

Ki-Won Lee, Gi Jun Choi, Ki-Yong Kim, Hee Chung Ji, Hyung Soo Park, Sei Hyung Yoon and Sang-Hoon Lee*

Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration, Cheonan, 330-801, Korea.

*Corresponding author. E-mail: sanghoon@korea.kr. Tel.: +82-41+580-6754.

Fax.: +82-41+580-6759.

Abbreviations: 2,4-D, 2,4-dichlorophenoxy acetic acid; BA, 6-benzyladenine; MS, Murashige and Skoog (1962) medium.

Accepted 25 August, 2009

   Abstract

In the present study, we have developed a high-frequency plant regeneration system for Italian ryegrass via callus culture using mature seeds as explants. Optimal embryogenic callus induction was found to occur in MS medium containing 5 mg l^-1 2,4-D, 0.5 mg l^-1 BA, 500 mg l^-1 L-proline, 1 g l^-1 casein hydrolysate, 30 g l^-1 sucrose, 7 mg l^-1 AgNO₃, 2 mg l^-1 CuSO₄ and solidified with 3 g l^-1 Gelrite. The highest regeneration rate was obtained in MS medium containing 1 mg l^-1 2,4-D, 5 mg l^-1 BA, 500 mg l^-1 L-proline, 1 g l^-1 casein hydrolysate, 1 mg l^-1 thiamine-HCl, 30 g l^-1 sucrose, 7 mg l^-1 AgNO₃, 2 mg l^-1 CuSO₄ and solidified with 3 g l^-1 Gelrite. By using the most effective treatment determined for each parameter, the highest rates of embryogenic callus formation (48.9%) and regeneration (47.6%) were obtained with the Hwasan 101 cultivar. The overall plant regeneration rates of the examined cultivars ranged from 7.5 to 23.2%. Thus, optimization of regeneration frequency using mature seeds as explant material may offer a simple and efficient protocol for Italian ryegrass that may improve molecular breeding of this species.

Key words: Italian ryegrass, Lolium multiflorum, embryogenic callus, plant regeneration, growth additives.