Trees need closure too - Do we have a genetic model to study and treat tree bark wounds?

Sachinthani I. Karunarathne, Antanas V. Spokevicius and Gerd Bossinger, School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, Australia, John F. Golz, School of BioSciences, Faculty of Science, The University of Melbourne, Australia

Background/Question/Methods
Bark wounds abound all ecosystems and usually remove the bark and damage underlying cambium/meristem and vascular tissues. Wounds that are not maintained could potentially be hazardous in the future because injuries expose trees to microbes that infect and cause discoloration and decay of the wood resulting in unhealthy, unsightly and unsafe trees with shortened lifespans. Wound treatments must reduce the rate of microbial invasion and cambial dieback by enhancing vascular tissue regeneration. However, no external treatments were proven to be as effective and as strong as the tree's new wood. Thus, improving the innate genetic machinery of new wood formation is key to developing promising wound treatments for plants. However, our knowledge about these wound signalling genetics remains scarce, mainly due to the lack of suitable models to study wound recovery genetics. Therefore, we present a novel genetic model based on Induced Somatic Sector Analysis (ISSA) technique. Our model first introduces genes to wound sites, then can genetically modify cells in the wound sites for enabling genetic analyses. Therefore, we present a genetic tool that can be used to study wound signalling qualitatively and quantitatively to unveil genetic mechanisms to treat tree wounds to maintain trees' health and survival.
Results/Conclusions
ISSA has been developed and successfully utilized in our lab for cambium differentiation and wood formation genetics as it reduces the time taken to produce transgenic cells/tissues in an intact stem by addressing many of the limitations of other routinely used in-vitro methods. Here we assessed the feasibility of using ISSA as a model to study the molecular control of the wound healing process. Firstly, results indicate that this method can be used to determine genus-specific wound responses. Secondly, we can compare wounded and non-wounded tissues in one and the same specimen side by side ( most significant ratio of 2:1 wounded: non-wounded). Thirdly, in contrast to the usual single-harvest opportunity of other methods, the high throughput capabilities of ISSA allowed sample collection in a time series, demonstrating this method’s convenient replicability. Lastly, microscopic imaging provided insights into the tissue-specificity of expression results. In conclusion, ISSA provided valuable clues about the type, quantity, tissue and time-specific gene expression during wound signalling. It, therefore, represents an innovative in-vivo transformation/screening system for studying genetics and molecular control of wound response and tissue regeneration and holds much promise for developing rapid, cheap, reliable, localized and tissue-specific treatments of wounds in mature tree stems.