Projects / Programmes
Time-course analysis of local and systemic changes in the defence chemistry and anatomy of Norway spruce in response to bark beetle attack
| Code |
Science |
Field |
Subfield |
| 1.03.04 |
Natural sciences and mathematics |
Biology |
Plant physiology |
| Code |
Science |
Field |
| B310 |
Biomedical sciences |
Physiology of vascular plants |
| B430 |
Biomedical sciences |
Sylviculture, forestry, forestry technology |
| B270 |
Biomedical sciences |
Plant ecology |
| B390 |
Biomedical sciences |
Phytotechny, horticulture, crop protection, phytopathology |
| B210 |
Biomedical sciences |
Histology, cytochemistry, histochemistry, tissue culture |
antioxidants, ascorbate, bark beetles, forest health, forest management, glutathione, defence induction, jasmonic acid, Norway spruce, photosynthetic pigments, Picea abies, resin ducts, salicylic acid, sclerified hypodermis, systemic acquired resistance;
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
28251 |
PhD Andreja Urbanek Krajnc |
Biology |
Head |
2007 - 2009 |
224 |
Organisations (1)
Abstract
Norway spruce [Picea abies (L.) H. Karst.] is the most abundant and economically important tree species in Slovenia. At low altitudes where it would not grow naturally, it is more sensitive to the rigours of the weather and to the more widespread bark beetles. Over recent summers´ extremely high temperatures and prolonged drought, which coincided with the fructification of Norway spruce, gave rise to an enormous propagation of bark beetles in Central Europe, causing huge damage and severe economic losses. The purpose of the proposed project is to investigate the spatial and temporal gradation of defence responses in Norway spruce from the initial attack to optimal colonization of bark beetles. Methyl salicylate (MS) will be applied to bark sections prior beetle attack, in order to study interactions with compounds involved in systemic acquired resistance (SAR) and its significance for mediating stress tolerance. The project work will be performed under natural conditions, regarding the nature of tree interactions with organisms involved in an attack (bark beetle-fungus association), environmental factors (drought stress, high temperatures) and forest management. The induction of local and systemic resistance relies on salicylic acid (SA) and jasmonic acid (JA) as major signalling compounds, but the information on both signal molecules in conifers, in response to pathogen challenge, is still limited. The primary task of this project work will be to investigate the sequence of changes in SA and JA contents in the tissue directly adjacent to the attack location (stem bark) and in the needles. MS treatment will make it possible to determine vertical rates of signal movement during a bark beetle attack. The study will also include antioxidative defence systems and chloroplast pigment analysis as stress indicators, in order to clarify how the initial reaction of antioxidative and photoprotective responses leads to acclimatization/ degradation and whether this response is dynamic or at a steady state. A further task of the project will be to identify any anatomical changes caused by MS treatment and bark beetle attack. Special attention will be given to cross-sectional areas of sclerified hypodermis in the needles and traumatic resin ducts in bark and wood, since these structures are relevant for the constitutive resistance of Norway spruce against bark beetles. The use of SAR as part of a disease management strategy in relation to forestry has received little scientific investigation despite offering some potential for tree pathogen control. Thus, this project´s main research priority will be to clarify whether resistance in Norway spruce can be induced by MS treatment, how long it will be effective, whether its effect will be systemic or localized, and whether MS treatment will be sufficient to protect trees from mass-attack by aggressive bark beetles and associated fungi. MS-treated trees will be studied for attraction, host colonization and reproduction of Ips typographus. If MS treatment can be shown to prevent beetle mass colonization and tree mortality, this could be of great benefit to an integrated forest pest management.
Significance for science
The time-course analysis of the salicylic acid and antioxidant defence molecules in affected spruces would provide an original input into the proposed project in regard to understanding metabolism, utilization and degradation of defence molecules, and their interactions. Transgenic conifers with altered defence profiles are now making it easier to test defensive roles. Even without transformation, the monitoring of defence molecules around the damaged site can readily implicate certain metabolites in defence response. They make it possible to prove tree´s defensive roles under natural conditions. However, the induction of systemic acquired resistance (SAR) by certain chemicals, the efficiency and persistence of SAR during bark beetle attack and the implication of chemicals in forestry management has received little scientific investigation as yet.
The project resulted in following original outcomes:
(1) The antioxidant defence system in Norway spruce during bark beetle attack is dynamic.
(2) It depends on the severity of attack. Upon successful defence, an acclimation stage can be reached. Unsuccessful defense during severe attack leads to degradation of antioxidants up to tree death.
(3) A sequence of changes in the endogenous levels of antioxidant defense molecules in the bark beetle-affected Norway spruce, showed consistency with the general ecophysiological stress-response concept.
(4) SA treatment had a surprising long-term effect on the accumulation of total SA and antioxidants in phloem of Norway spruce.
(5) Exogenous SA induced the local and systemic defence responses of Norway spruce against bark beetle attack.
(6) SA treated trees were characterized by anatomical changes (increased number of resin ducts and polyphenolic parenchima cells) and increased resin flow.
(7) SA treatment suppressed the bark beetle entrance and gallery formation.
From this perspective, SA treatment will remain an important part in assessing antioxidant defense response in trees and could be of great benefit to an integrated forest pest management. The project would provide a broad input into current research covering basic research fields, tree physiology, phytopathology, forest ecology, forest protection and management. Furthermore, the project work provided additional data, in order to establish larger databases on biochemical stress markers in field studies. The project research fits in well with the special priorities of Slovenian National Forestry Program (NFP), since it provides new knowledge important for educational needs and sustainable forestry management.
Significance for the country
Bark beetles represent the most significant and harmful species in economic terms. Thus, forest protection is a constant concern in the both Slovenia and the EU.
The proposed project deals with the disease resistance of trees against bark beetles. The aim of the project is to get an insight into the SA dependent defence mechanisms on conifers, which could contribute to the preservation of valuable forest areas in Slovenia.
The results of the presented project demonstrated, that SA treatment (1) stimulated the synthesis of antioxidants in Norway spruce, (2) inproved the effectiveness of defense response against bark beetle attack and (3) was shown to prevent beetle mass colonization and tree mortality. The treatment experiments in the proposed project are crucial for the development of new practices at the protection of Norway spruce against severe epidemics of bark beetles without changing the genetic information.
The induction of systemic aquired resistance in combination with other control measures would avoide increased costs of tree felling and wood gathering, felling before time, increased cost of forest protection, forest restoration, tending of attacked trees, wood devaluation etc.
The implication of systemic aquired resistance with chemical agents like SA would contribute to the forest preservation in Slovenia. The project contents coincided with a set of eighteen key actions of the EU Forest Action plan 2007–2011 (COM(2006) 302 Final). The Commission wants to strengthen the competitiveness of the European forestry industry while at the same time respecting the goals of sustainable forest management. Key action 9 of this action plan envisages the protection of EU forests against biotic and abiotic stress factors as one of the main priorities of EU forest policy. The Commission also supports research on the protection of forests and phytosanitary issues under the 7th Research Framework Program. Slovenia as a member state is encouraged to review and update broader protection strategies against biotic and abiotic stress factors, including studies of harmful organisms and invasive species. Also, member states are advised to form groupings to study particular regional problems concerning the condition of forests. In this manner, the project fits perfectly well into the key action 9 of the EU Forest Action Plan and supports a common approach towards the sustainability of Slovenian and broader EU forests. On the other hand, the theme of the project also encompass one of the research themes in the first priority group (i.e. forest, innovative and sustainable use of wood) of the Ministry of higher education, science and technology of the Republic of Slovenia. These efforts, along with continuing support to the EU ongoing forest programmes would help to ensure that the conservation and sustainable management of forests continues to make an important contribution to the attainment of the major development goals of the Republic of Slovenia and the priorities of Slovenian National Forestry Programme (NFP).
The project aim was not only to maintain economic function of forests as a source of timber or wood for furniture, paper, paperboard or energy (biomass), but also to provide important ecological functions (biodiversity, protection of water and soil, climate change mitigation) and social functions (recreational services, tourism), which are threatened by the bark beetles´ attacks. The later two functions are of significant importance especially for Slovenian forest reserves (e.g. Trnovo, Šumik, Boč, Plešivec, Bukovžlak etc.), parks and botanical gardens where the forest´s health is of great importance. The project supports common efforts to maintain the different functions that Slovenian forests provide for society, like supplying renewable and environmentally friendly raw materials and playing an important role in the economic development, employment and prosperity of Europe, in particular of rural areas.
Most important scientific results
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Most important socioeconomically and culturally relevant results
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