First Data From a Field Trial of Quercus Suber Plants Regenerated From Mature Selected Trees and From Their Half-Sib Progenies by Somatic Embryogenesis

Abstract

The development of reliable clonal propagation technologies is a requisite for performing Multi-Varietal Forestry (MVF). Somatic embryogenesis is considered the tissue culture based method more suitable for operational breeding of forest trees. Vegetative propagation is very difficult when tissues are taken from mature donors, making clonal propagation of selected trees almost impossible. We have been able to induce somatic embryogenesis in leaves taken from mature oak trees, including cork oak (Quercus suber). This important species of the Mediterranean ecosystem produces cork regularly, conferring to this species a significant economic value. In a previous paper we reported the establishment of a field trial to compare the growth of plants of somatic origin vs zygotic origin, and somatic plants from mature trees vs somatic plants from juvenile seedlings. For that purpose somatic seedlings were regenerated from five selected cork oak trees and from young plants of their half-sib progenies by somatic embryogenesis. They were planted in the field together with acorn-derived plants of the same families. After the first growth period, seedlings of zygotic origin doubled the height of somatic seedlings, showing somatic plants of adult and juvenile origin similar growth. Here we provide data on height and diameter increases after two additional growth periods. In the second one, growth parameters of zygotic seedlings were also significantly higher than those of somatic ones, but there were not significant differences in height increase between seedlings and somatic plants of mature origin. In the third growth period, height and diameter increases of somatic seedlings cloned from the selected trees did not differ from those of zygotic seedlings, which were still higher than data from plants obtained from somatic embryos from the sexual progeny. Therefore, somatic seedlings from mature origin seem not to be influenced by a possible ageing effect, and plants from somatic embryos tend to minimize the initial advantage of plants from acorns.

Application of biotechnological tools to Quercus improvement

“…Differences as a result of genotype and family effects were notable and no apparent morphological alterations were detected among the trees of tested progenies (Celestino et al 2007). …”

Improved organogenic capacity of shoot cultures from mature pedunculate oak trees through somatic embryogenesis as rejuvenation technique

“…As well, an influence of the different mean root number produced by these plantlets in vitro (Table 2) could also cause this difference, especially during the first period of growth after transplanting. In contrast, no differences were found between cork oak somatic plants of adult (epicormic shoots) and juvenile (seedlings from halfsib acorns of the adult trees) origin after the first growing season in the field (Celestino et al 2007). However, apart from a possible genotypic effect, a different experimental model was used in cork oak in which plants were derived from germinated somatic embryos, whereas in this study somatic embryo-derived clones and rooted plants were used.…”

Biotechnological efforts for preserving and enhancing temperate hardwood tree biodiversity, health, and productivity

“…Higher numbers of globular-, heart-, torpedo-, and cotyledon-stage somatic embryos were then obtained after culture on medium devoid of 2,4-D, with germination and development of plants after desiccation and cold storage. In vitro studies on Q. suber embryogenesis and diploidization of antherderived embryos (for breeding purposes) continues to advance the improvement, conservation, and production of this important forest and agro-forestry species (high-quality cork; acorns for feed for cattle and pig farming; Celestino et al 2007Celestino et al , 2009Pintos et al 2007Pintos et al , 2008Gomez et al 2009). Anther-derived haploid embryos from six genotypes were treated with three different anti-mitotic agents, and 0.01 mM oryzalin (for 48 h) produced approximately 50% diploid embryos (Pintos et al 2007).…”

“…Pintos et al (2008) encapsulated somatic embryos of cork oak for the production and storage (4°C for 2 mo without significant loss) of synthetic seeds, and monitored the growth with a digital image system. Celestino et al (2007Celestino et al ( , 2009 and Pintos et al (2009) reported on field trials of cork oak plants regenerated via somatic embryogenesis, and they concluded that the regenerated plants showed a cork quality trait similar to that of the parent tree. Proteomic analysis of haploid and diploid embryos of cork oak identified 17 differentially expressed proteins; of which some were involved in the synthesis of cork chemical components (Gomez et al 2009).…”