Abnormal Somatic Embryo Reduction and Recycling in Grapevine Regeneration

Abstract

The purpose of the study was to increase plant conversion efficiency and reduce waste of the abnormal somatic embryos; factors influencing both the embryo morphology in germination and the embryogenic callus reinduction rate in secondary embryogenesis were studied in Vitis vinifera L. ‘Thompson Seedless.’ Embryos having mono-, di-, and multiple-normal cotyledons, trumpet-shaped, fascicular, and fused abnormal cotyledons were observed during germination. Normal embryos of one, two, and multiple cotyledons have a relatively higher conversion rate (48.89–64.44%) than abnormal ones (2.22–22.22%). Histomorphology analysis of these embryos showed that normal somatic embryos had a better developed vasculature and shoot meristem than abnormal individuals. A lower percentage of abnormal embryos formed when they germinated on Murashige and Skoog’s medium (MS) and Woody Plant Medium (WPM) both of which contained 15 g/l sucrose and no plant growth regulators. Of all the abnormal embryos, only fused cotyledon embryos were suitable for recycling, and they were reinduced into the embryogenic callus. Cotyledons showed a higher reinduction rate (72.22%) than the other two parts: hypocotyls (4.44%) and roots (0%). In addition, recycled abnormal embryos produced many morphogenic types and this secondary embryogenesis could be used for embryo proliferation.