Interaction between abiotic and biotic stresses: salinity and herbivory in woody plants

盐碱化影响了北美约10万公顷的灌溉土地。此外，在加拿大，采矿扰乱了我们的生态系统，导致含盐量相对较高的土地区域，必须重新开垦以支持森林生态系统。土壤中盐的存在通过减少水分吸收（渗透胁迫），诱导离子（Na+和Cl-）毒性，引起营养失衡以及产生自由基（氧化胁迫）来限制植物生长。尽管分子技术的发展已经允许表征大量参与应激反应的基因；我们对北方木本植物耐盐机制的了解需要更多的研究来选择能够在北方森林盐影响土壤上生长的植物。此外，为了在盐度胁迫下生存，植物会经历一些生理变化，改变植物对其他胁迫（包括生物胁迫）的生化反应途径。昆虫食草是一种生物压力，是北方森林的一个主要问题，可能会随着气候变化对我们的森林生态系统造成进一步的破坏。我们在农作物上的初步实验表明，草食和盐度之间的相互作用可能因植物的耐盐性和氮状态而异。我的研究项目拟结合生理、生化和分子技术，对北方森林木本植物盐度与昆虫取食的相互作用进行创新性研究。本研究的目的是：(1)确定耐盐胁迫是否增加了植物抵抗食草昆虫攻击的能力；2)研究植物生长调节剂茉莉酸（jasmonic acid， JA）在盐度与草食相互作用中的作用。茉莉酸不仅在植物对草食诱导防御机制（次生化合物的产生）的响应中起着关键作用，而且在非生物胁迫（干旱和盐度）中也起着关键作用。JA水平对盐度的响应是否有助于植物限制草食攻击？3)确定盐诱导的氮素代谢变化是否会影响昆虫的草食抗性。盐胁迫下氮转运和同化的变化可能会抵消盐诱导的营养失衡，这取决于物种的耐盐性，因此可能影响食草性。这项研究将由10名学生在温室的受控条件下进行，他们将获得宝贵的环境生理学专业知识。这项研究将补充现有的北方生态系统研究，并将推进我对耐盐机制和胁迫间相互作用的研究计划。它还将提供工具，帮助制定战略，成功地恢复北方森林中受到干扰的地区，并限制人类活动对环境的影响。

Salinity affects around 10 M ha of irrigated land in North America. In addition, in Canada mining has disturbed our ecosystems, resulting in areas of land with relatively high salt content, which must be reclaimed to support forest ecosystems. The presence of salts in the soil limits plant growth by reducing water uptake (osmotic stress), inducing ion (Na+ and Cl-) toxicity, causing nutrient imbalance as well as producing free radicals (oxidative stress). Although the development of molecular techniques has allowed the characterization of a large number of genes involved in stress response; our knowledge of the mechanisms of salinity tolerance of northern woody plants requires more research to select plants that can grow on salt-impacted soils in the boreal forest. Furthermore, to survive salinity stress, plants undergo physiological changes that alter the biochemical pathways involved in plant response to other stresses including biotic stress. Insect herbivory is a biotic stress that is a major concern in the Boreal forest and could cause further damage to our forest ecosystems with climate change. Our preliminary experiments on agricultural crop species suggest that the interaction between herbivory and salinity could vary depending on the salt tolerance of the plants and their nitrogen status. My research program proposes to combine physiological, biochemical and molecular techniques to conduct innovative research on the interaction between salinity and insect herbivory in woody plants for the Boreal forest. The objectives of the proposed research are 1) to determine if tolerance to salinity stress increases the ability of the plants to resist insect herbivore attack; 2) To study the role of the plant growth regulator, jasmonic acid (JA) in the interaction between salinity and herbivory. JA plays a key role not only in the response to herbivory to induce defense mechanisms (production of secondary compounds) but also in abiotic stress (drought and salinity). Could the change in JA level in response to salinity help the plant limit herbivory attack? 3) To determine if salt-induced changes in nitrogen (N) metabolism could affect insect herbivory resistance. Changes in N transport and assimilation under salinity stress could occur to counterbalance salt-induced nutrient imbalance depending on the salinity tolerance of the species and therefore potentially affect herbivory resistance. This research will be conducted under controlled conditions in a greenhouse by 10 students who will gain valuable expertise in environmental physiology. This research will complement existing research on northern ecosystems and will advance my research program on salt tolerance mechanisms and the interaction between stresses. It will also deliver tools that will help to develop strategies to reclaim successfully disturbed areas in the Boreal forest and limit the impact of human activities on the environment.