Cork oak (Quercus suber) is a forest tree native to south-western Europe and African countries of the western Mediterranean region, where is a key species due to its ecological and socioeconomic importance. In Portugal, is a dominant evergreen species of the â€œmontadosâ€, covering 23% of the Portuguese total forest area and providing 54% of the world cork production (34% of the Portuguese total forest exports). However, there is little understanding of the causal mechanisms of cork oak adaptability to different environmental conditions in its natural range. The area covered by Q. suber woodlands has been progressively declining in some parts of its western Mediterranean range. In addition to a progressive decline in woodland area, cork oak often shows reduced natural regeneration. This has led the Common Agriculture Policy (CAP) to
promote cork oak afforestation programs for large areas of south-western Europe in recent years. However, artificial regeneration either by direct seeding or planting has shown heterogeneous results, with low survival rates. Moreover, successful artificial regeneration requires the understanding of host-pathogen interactions, which is being targeted in other studies. The need to improve seed handling, nursery and planting techniques is usually recognized by landowners, but seldom is the use of suitable genetic material considered. This may have critical implications for sustainable forest management to face the challenges of climate change (1). The present project aims to improve the quality of cork oak germplasm used for reforestation, both at the physiological and genetical levels. In particular, it aims to strengthen our understanding of the adaptability of this species, long-term seed storage and seed production.
Considering that genetic improvement is a component of sustainable forest management, the present project aims to be a first step towards a Q. suber comprehensive breeding program. The need for genetic improvement in cork oak has been stressed by Kellison et al. (2), and preliminary results (3) from multi-environment provenance trials (4) have indicated significant genetic variability for adaptive traits, suggesting that seed origin must be considered in reforestation programs. So far, several studies with biochemical and molecular markers have showed generally high levels of genetic variation within cork oak populations, but moderate amount of geographic differentiation among them (5). Although the use of molecular markers makes possible to infer about the genetic structure of the species, it is well known that it may not reflect the variation in adaptive traits. Therefore, the assessment of morphological, physiological and biochemical traits in selected contrasting populations under controlled conditions will allow a better understanding of the underlying biological mechanisms influencing drought tolerance and supporting silvicultural recommendations for specific sites. We will integrate results from different approaches â€“ ecophysiology, quantitative genetics and molecular biology â€“ to assess phenotypic plasticity in drought stress and to develop seed transfer guidelines and seed procurement zones for afforestation on the basis of provenance response to changes in environmental conditions. Since a genetic improvement program must have a sustainable deployment strategy for largescale operational planting, we will assess seed production precocity and the acorn susceptibility to fungi in a seed orchard established by grafting in 2002. This knowledge will be useful to accomplish an efficient artificial regeneration program through seed propagation. In addition, deployment of acorn from selected stands or seed orchards requires long-term seed storage due to variable and unpredictable reproduction patterns of cork oak trees (1). Our group has already developed a new cork oak seed storage technique (Portuguese patent nÂº 103611- 26/9/2008) that allows planning seedling production and promoting an increase in field survival, a fact that has already been recognized by forest stakeholders. Although acorn is available during all the year without loss of viability, fungi infection has been detected after seventeen months of storage. This is one of the main problems to maintain the seed in good conditions (6). Ciboria batschiana has been described as the main acorn contamination agent of Q. suber seeds, but scarce information is available concerning the species characterization. In this context, we propose to study the infection cycle, covering flowering and fruit maturation, seed collection and seed storage. Based on this information, we expected to contribute for a better characterization and identification of Ciboria batschiana as a seed infection fungus, which will be useful to design and test alternative procedures for seed treatment. This will extend the storage time without loss of seed viability and sanity.