ESTABLISHMENT OF EFFICIENT SOMATIC EMBRYOGENESIS AND REGENERATION IN MUSCADINE GRAPE (VITIS ROTUNDIFOLIA)

Abstract

Muscadine grape (Vitas rotundifolia Michx.), a native of the southeast USA, is recognized as the most resistant species to major grape diseases/pests. The Muscadine berries also possess unique health-beneficial compounds that have potential for value added product development. However, its consumer acceptability as a table grape is generally limited by some characteristics of the fruits, e.g., seediness, tough skin, short shelf life, etc. Introgression of better fruit quality from the European grape (V. vinifera L.) to muscadine grape through conventional breeding has been hampered by interspecific barriers and hybrid infertility. Gene transfer is considered an important alternative approach for improving muscadine fruit quality. Successful genetic transformation for grape improvement requires a reliable and efficient in vitro regeneration system. Somatic embryogenesis provides a unique capability for consistent plant regeneration and long-term supplies of materials for genetic improvement of muscadine grape cultivars. Embryogenic cultures were successfully induced from various tissues including ovules, anthers, petioles and leaves, with different medium and supplement combinations. The embryogenic lines were repeatedly multiplied in both solid and liquid media without losing embryogenic competence. A high productivity of synchronized somatic embryo recovery was achieved in suspension culture. More than 95% of these somatic embryos could germinate and develop into normal plantlets within 30 days after transfer to regeneration medium with appropriate supplements.