IN VITRO MICROPROPAGATION OF ZYGOTIC EMBRYOS TO FACILITATE GENETIC ANALYSIS IN HAZELNUT (CORYLUS AVELLANA L.) PROGENIES
Genetic analysis of seedlings from full-sib (FS) progenies in highly heterozygous fruit trees allows estimation of genetic and environmental variances. Seedling cloning can provide the replicates needed for measurements, and biometrical analysis allows the estimate of the upper limit of the heritability of a trait. We describe a method for cloning seedlings of hazelnut (Corylus avellana L.) resulting from controlled pollinations among four clonal landraces. It is based on axillary shoot multiplication from the leaf nodes (micro-cuttings) of the primary shoot developed from the excised zygotic embryonic axis grown in vitro. About 50% of the excised embryonic axes germinated in vitro and gave normal seedlings with 5 to 7 leaf nodes. The proportion of micro-cuttings which proliferated an axillary shoot after excision from the primary embryo shoot at leaf node position 1 (the node right below the apical meristem of the seedling), 2 and 3, was ≥0.9, but decreased to 0.6 for micro-cuttings taken from leaf nodes at position 4, and to 0.32 for micro-cuttings from the basal node. These proportions were not significantly affected by the variation in maternal effects among full-sib progenies. The average number of axillary shoots developed from each seedling was 2.5. The G-medium-C supplemented with Indol Butyric Acid at 1.5 mg L-1 allowed rooting of ≥80% of the axillary shoots. Using the proposed protocol it is possible, in less than three months, to produce the 4 to 6 ramets needed for repeated measurements and genetic analysis of hazelnut full-sib seedling traits, which is a significant acceleration compared to the traditional methods of cloning based on grafting, or sucker and shoot rooting.
Gutiérrez Pesce, P., Catarcione, G., Rugini, E. and De Pace, C. (2013). IN VITRO MICROPROPAGATION OF ZYGOTIC EMBRYOS TO FACILITATE GENETIC ANALYSIS IN HAZELNUT (CORYLUS AVELLANA L.) PROGENIES. Acta Hortic. 976, 291-298
tree breeding, embryo rescue, fruit quality, pollen effect, repeatability, heritability, breeding value