Abstract
Development of hybrid pines of Pinus radiata D. Don for commercial forestry presents an opportunity to diversify the current resource of plant material. Climate change and different land uses pose challenges, making alternative species necessary to guarantee wood and non-wood products in the future. Pinus radiata var. cedrosensis × Pinus attenuata hybrid possesses different attributes, such as tolerance to drought conditions, better growth and resistance to snow damage at higher altitudes, and more importantly, different wood quality characteristics. Embryogenic cell lines were successfully initiated reciprocal hybrids using as initial explants megagametophytes, excised zygotic embryos and excised zygotic embryos plus nurse culture. However, the questions raised were: does the initiation environment affect the conversion to somatic plantlets months later? Does the mother tree or the cross have an effect on the conversion to somatic plantlets? In the present work we analysed the maturation rate, number of somatic embryos, germination rate, and the ex-vitro growth in cell lines derived from different initiation treatments, mother tree species, and crosses. Differences were not observed for in vitro parameters such as maturation and germination. However, significant differences were observed due to the mother tree species in relation with the ex-vitro growth rates observed, being higher those in which P. radiata acted as a mother. Moreover, embryogenic cell lines from these hybrids were stored at −80 °C and regenerated after one and five years.
Highlights
Pinus spp. are frequently used in reforestation programs and, Pinus radiata D
Different embryogenic cell lines (ECLs) analysed for each cross showed a different maturation rate ranging from 67 % to 100% (cross 887.301 with P. attenuata as mother tree and cross 886.975 with P. radiata as the mother tree, ECLs from the rest of crosses showed maturation rates between 83 and 89% (Figure 2a)
Different initiation treatments provoked a variation in the success of the process depending on the species that acted as mother; Treatment 1 was the most successful when P. attenuata was the mother and the worst when this species was the father
Summary
Pinus spp. are frequently used in reforestation programs and, Pinus radiata D. P. attenuata, for instance, can potentially contribute to drought, cold and snow damage resistance acquisition in P. radiata, which does not have those attributes [6]. In this sense, hybrid pines have been recognised as an opportunity for the future [7,8]. Bearing in mind the information about P. attenuata pure species, some years ago we started studying the drought stress tolerance mechanism of the hybrid P. attenuata × P. radiata trying to understand the mechanisms involved in this process [9]. Some field studies have been carried out to evaluate the performance of the P. attenuata × P. radiata hybrid for afforestation in New Zealand [7]
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