Micro-propagation of fibrous species

Micro-propagation of fibrous species One of the central axes of the research performed in the Forestry Biotechnological Laboratory (LBF) is the strengthening of the multiplication capacities of fibrous species through vegetal strengthening and renewal. Since 1999, this Laboratory, which is part of the Faculty of Forestry Sciences, has investigated and tested several micro-propagation techniques in exotic and native trees that are important in the lumber (radiata pine, eucalyptus, poplar, oak, among others); fruit (chestnut, cherry, walnut and hazelnut); and environmental (hazelnut, pitao, keule) plantations.

In most cases, the propagation based on embryonic tissues (seeds) or asexually (posts, grafted, among others), has been successfully achieved, assisting in another scientific objective of LBF: generate elite genotypes.

Organogenesis and embryogenesis

Micro-propagation is part of vegetal propagation and permits plant multiplication based on small portions of vegetal tissue.

Also know as in vitro cultivation, it is associated directly with organogenesis and somatic embryogenesis.

The first one permits organic formation from tissue particles or from complete organs (leaves, stems, yolks). The second one is oriented to the obtainment, from somatic (asexual) tissues, similar structures to the ones that originated sexual fecundation and the subsequent seed formation.

These structures, called somatic embryos, have the same form and functioning of a sexually originated natural embryonic axis, although it does not have endosperm or reserve material.

LBF has performed basic research on both processes. Their emphasis has been in the somatic embryogenesis of fibrous trees because it offers more options of tissue manipulation. The somatic methodologies for oak and raulí (with which the greatest advances have been made) have already been established, and researchers are at the point of achieving it with eucalyptus (globulus and nitens) and chestnut, in which the maturation and germination phases of the produced embryos as well as their encapsulation to generate artificial seeds are still in process

Mature seed versus immature seed

In vitro cultivation, sexually, it is important to note the tissue’s development stage at the moment of collection. The best results are achieved with immature seeds, although they have the disadvantage of a time limit for collection from the mother trees and germoplasm manipulation when there is no adequate storage. As an alternative, LBF has experimented with adult seeds, standardizing the multiplication protocols for eucalyptus (globulus and nitens), radiata pine, araucaria, roble, raulí, coigüe, hazelnut, walnut, chestnut, cherry, pitao, poplar, whose plants have been tested in the field.

The adult path

Despite the advantages associated with sexually produced seeds, LBF has established a line of work with somatic tissue. In this case, the age of the mother plant plays a fundamental role.

The majority of the research has been with young plants. However, the Laboratory developed the program with tissues collected in adult plants, where the selection of the genotypes is simpler because all their characteristics can be seen.

In this area, successful results have been achieved in fruit species such as chestnut and walnut as well as in the lumber species of radiata pine and eucalyptus globlus. These results are being confirmed in greenhouses and plantations.

This year, we hope to establish the first plantation of chestnuts selected and multiplied using this technique in addition to plots of the Chilean hazelnut for its wood and fruit production.

Youth inductors

Searching for the greatest applicability of selected genotype multiplication, LBF is researching the improvement of adult material through the use of youth inductors. The Laboratory has finished the bio-chemical and physiological studies on the relation between adult and juvenile tissues as well as the management of the reciprocal effects at a metabolic level.

The idea is to transmit the juvenile metabolism to the old tissues so that they reproduce and grow at a greater velocity. The process consists in submitting the chosen tree’s sleeping yolks to a climatic stimulation process (performed in the Laboratory) to be later planted, cultivated in vitro or destined to proliferate chains that reproduce the genetic material from portions of leaves, stems, or roots. The technique has been applied in the propagation of chestnut and could be extended to other species.