Quercus

Introduction

Photo JM Gion, CIRAD

Forest covers 26.6% of the earth’s land surface, and is constantly diminishing due to agricultural pressure, especially in tropical zones. Accounting for 2% of the world’s gross domestic product, forestry is the world’s fifth most important economic sector, with wood pulp, paper and lumber industries representing 60% of the market. Wood is also a source of renewable natural energy and constitutes a major carbon dioxide sink. In 1995 it was estimated that 75% of industrial wood was produced by “ natural forests ”, and 25% came from industrial plantation. During the next decades, the increase in the population (8 million people in 2020) should lead to a major increase in demand for wood (+25% between now and 2010, data from the FAO), especially in developing countries. In order to avoid abusive exploitation, the following recommendations were set forth at the Earth Summit in Rio de Janeiro in 1992 :

• Reduction of the contribution of natural forests by 30%
• Increase of 40% in the contribution from industrial tree plantations and from recycling.

These statistics clearly indicate the necessity of increasing the production of wood by dedicated industrial tree plantations, while trying to avoid the pressure exerted on old growth forests. An increase in productivity requires the adoption of optimized forestry practices, as well as the development of genetically improved varieties. Forest species are still only slightly domesticated; they exhibit high genetic diversity and considerable progress can be expected during the first cycles of selection. Thus, with the increasing need for wood by industry and society, cultivated forests will have a more and more important economic role to play. However, in a changing world, production goals should take the rapid evolution of the economy into account (demand for quality raw materials) as well as the expected environmental changes (global change). Thus it is not only a matter of adopting a simple productivist plan for our temperate forests, but we must take other factors into account in order to ensure their perpetuity. Ensuring the quality of the raw materials and the adaptation of trees to the environment which produces them constitute two important criteria for the sustainability and multifunctionality of forest ecosystems which were enunciated at three inter-ministerial conferences on the protection of European forests (Strasbourg 1990; Helsinki, 1993; Lisbon, 1998).

The activities undertaken involving the various species of the ForEST project integrate into these international engagements and endeavor, to develop two research themes: quality of wood and adaptation to the environment. Since sustainable management of forests requires a knowledge of the molecular and physiological mechanisms of tree functioning, the scientific goal of our project is to identify the genes of ecologic and economic interest to better manage forest genetic resources and to enhance their value. Concretely, this means utilization of molecular tools in the context of improvement programmes for the exploitation of genetic resources, and in the context of conservation programmes for the management of genetic resources.

OAK: Evaluation of the genetic diversity of the genes implicated in the adaptation of trees to their environment

The sessile and pedunculate oaks are the two most important species of deciduous trees in Europe in terms of forest surface cover and in terms of economics (wood resources). These two species are sympatric but occupy different ecological niches: the pedunculate oak grows in humid areas which are rich in minerals and can withstand high moisture content of the soil, but is very sensitive to drought, whereas the sessile oak requires drier soil which has better drainage and is less rich in minerals.
The environmental constraints sustained by our temperate forests are principally linked to climactic factors (drought, wind, fire). They will be amplified during the next decades by global warming. These modifications will generate selection pressures which will affect their adaptation to an environment with less water. The availability of water is the principal limiting factor for growth and even survival of trees. Furthermore, the predicted climate changes are characterized by modifications in the length of the growing seasons (the date of vegetative bud break is dependent on this). In particular, an increase in the length of the growing season will make trees more sensitive to climactic factors (early or late frost). In this context it is urgent to understand the response and adaptation capacities of the trees to these brutal changes. We propose to contribute to answering these questions by using the tools of functional genomics (transcriptome, proteome, genetic mapping and detection of QTL, association studies in natural populations), taking the genetic diversity of oak trees into account. The approach that we plan to use relies on competency in genetics (molecular, quantitative and population) at the BIOGECO mixed unit research, as well as a collaboration with ecophysiologists from INRA in Nancy (UMR Ecologie et Ecophysiologie Forestière).