ISHS Acta Horticulturae 521: XXV International Horticultural Congress, Part 11: Application of Biotechnology and Molecular Biology and Breeding - Gene Expression and Molecular Breeding, Genome Analysis.
GROWTH CHARACTERISTICS OF THE UNTRANSFORMED AND TRANSFORMED APPLE ROOTSTOCK M26 WITH ROLA AND ROLB GENES UNDER STEADY-STATE NUTRIENT SUPPLY CONDITIONS |
| Authors: | L.H. Zhu, M. Welander |
| Keywords: | rol gene, Apple, dwarfing, rootstock M26, steady-state |
| Abstract:
Growth characteristics of micropropagated untransformed and transformed plants of the apple rootstock M26 (Malus domestica) were investigated. Transformed plants included two clones with the rolA gene (rolA1 and rolA2) and one clone with the rolB gene (F). Ingestad's steady-state experimental system was employed to evaluate growth characteristics of the plants grown under non-limiting nutrient conditions. The plants were grown in growth units in which the culture solution was sprayed onto the roots continuously in a controlled climate chamber. By using pH titration which was done automatically every 10 minutes, nutrients were added to the culture solution based on relative addition rate which equals relative growth rate of plants growing at the exponential growth phase. Under non-limiting nutrient conditions, the relative growth rate of rolA1 and rolB was significantly reduced compared to the untransformed plants. The degree of growth reduction was more pronounced for rolA1. Leaf area ratio and specific leaf area did not differ significantly among different plants. Internode length tended to decrease for the transformed plants compared to the untransformed ones. Specific root length was increased significantly for rolA1, while no differences were observed for the other two transformed clones compared to the untransformed plants. Dry biomass allocation and the shoot to root ratio were not altered by the introduction of the rol genes. Visual observations showed that rolA1 plants had darker green and slightly wrinkled leaves compared with the untransformed plants. | |
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