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

在北美，盐度影响着大约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，导致一些地区的土地含盐量相对较高，必须开垦这些土地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。虽然分子生物学技术的发展已经允许表征大量的基因参与应激反应，我们的知识的耐盐机制的北方木本植物需要更多的研究，以选择植物，可以生长在盐影响的土壤中的北方森林。此外，为了在盐胁迫下生存，植物经历生理变化，这些生理变化改变了植物对包括生物胁迫在内的其他胁迫的响应中所涉及的生化途径。昆虫植食性是一种生物压力，是北方森林的一个主要问题，并可能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，草食动物和盐之间的相互作用可能会有所不同，这取决于植物的耐盐性和氮素状况。我的研究计划是将联合收割机的生理、生化和分子技术相结合，对北方森林木本植物中盐分与昆虫植食性的相互作用进行创新性研究。本研究的目的是：1）确定植物对盐胁迫的耐受性是否增加植物抵抗植食性昆虫攻击的能力; 2）研究植物生长调节剂茉莉酸（JA）在盐和植食性昆虫之间的相互作用中的作用。JA不仅在响应草食动物诱导防御机制（产生次生化合物）中起关键作用，而且在非生物胁迫（干旱和盐）中也起关键作用。JA水平对盐度的反应是否有助于植物限制植食性攻击？3)确定盐诱导的氮代谢变化是否会影响昆虫的植食性。盐胁迫下N运输和同化的变化可能会发生，以抵消盐引起的营养失衡，这取决于物种的耐盐性，因此可能会影响草食动物的抗性。这项研究将由10名学生在温室中的受控条件下进行，他们将获得环境生理学方面的宝贵专业知识。 这项研究将补充现有的北方生态系统的研究，并将推进我的耐盐机制和压力之间的相互作用的研究计划。它还将提供有助于制定战略的工具，以恢复北方森林中成功受干扰的地区，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. *****