| Popis: |
Pines are important because they are major components of many forest ecosystems, but also because, more generally, they have great environmental, economic, and aesthetic value. Pathogen attack greatly reduces the value of these trees. Pines have evolved constitutive and induced defenses to combat pathogens. Constitutive defenses are produced all the time and function to prevent infections from establishing in the first place. Induced defenses form after pathogen recognition and involve both local and systemic responses. Around an infection, trees mount additional defenses to compartmentalize, inhibit, or otherwise eliminate the pathogen as part of a localized induced resistance (LIR) response. An increase in defense-associated compounds also occurs systemically following infection and is often associated with a systemic induced resistance (SIR) response. The major aim of this research was to utilize a system comprising Austrian pine (Pinus nigra), a common landscape tree, and two fungal pathogens belonging to the genera Diplodia, to explore different aspects of how pines defend themselves against pathogens. The major objectives of this research were to: 1) discover biochemical changes that occur as part of the induced resistance response, with an emphasis on the defense-associated phenolics and terpenes; 2) discover the effects of fertility on defense compounds; and 3) identify potential systemic signaling molecules of induced defense responses in pine. This research showed that: 1) phenolic compounds increase both locally and systemically (in the phloem and xylem) following pathogen infection; 2) terpenes are induced around an infection site but not systemically; 3) phenolics positively associated with SIR; 4) terpenes appear linked only to LIR; 5) soil fertility affects the accumulation of phenolic compounds in induced defense only, while terpene compound production is affected only in non-infected trees; and 6) no phenolic compounds could be linked with systemic signaling in the context of this study. Knowledge about how pines deploy defense responses will be useful in developing new strategies that could more effectively manage pine diseases as well as better preserve the ecological, environmental, economical, and aesthetical values of pines. |
