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

盐碱度影响着北美约1000万公顷的灌溉土地。此外，在加拿大，采矿扰乱了我们的生态系统，导致盐分含量相对较高的地区，必须开垦才能支持森林生态系统。土壤中盐分的存在通过减少水分吸收(渗透胁迫)、诱导离子(Na+和Cl-)毒性、导致营养失衡以及产生自由基(氧化胁迫)来限制植物的生长。虽然分子技术的发展使得大量参与逆境反应的基因得以表征，但我们对北方木本植物耐盐性机制的了解需要更多的研究来选择能够在北方森林受盐分影响的土壤上生长的植物。此外，为了在盐胁迫下生存，植物经历了生理变化，这些变化改变了植物对包括生物胁迫在内的其他胁迫的反应的生化途径。昆虫食草性是一种生物胁迫，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破坏。我们对农作物物种的初步实验表明，草食和盐分之间的相互作用可能会因植物的耐盐性和氮素状况而有所不同。我的研究计划提出将生理、生化和分子技术相结合，对北方森林木本植物中盐分和昆虫食草性之间的相互作用进行创新研究。这项研究的目的是：1)确定耐盐性是否提高了植物抵抗昆虫食草动物攻击的能力；2)研究植物生长调节剂茉莉酸(JA)在盐分和食草性之间相互作用中的作用。JA不仅在对食草性植物诱导防御机制(产生次生化合物)的反应中发挥关键作用，而且在非生物胁迫(干旱和盐分)中也发挥关键作用。JA水平的变化是否有助于植物限制食草性攻击？3)确定盐诱导的氮(N)代谢的变化是否会影响昆虫的食草性。盐分胁迫下氮素运输和同化的变化可以抵消盐分诱导的营养失衡，这取决于物种的盐分耐受性，因此可能会影响草食抗性。这项研究将在温室中由10名学生在受控条件下进行，他们将获得宝贵的环境生理学专业知识。这项研究将是对北方生态系统现有研究的补充，并将推进我的耐盐机制和胁迫之间相互作用的研究计划。它还将提供工具，帮助制定在北方森林中成功开垦受干扰地区的战略，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.