植物代谢在盐碱等胁迫下发生了复杂多样的变化，但由于技术的限制，盐碱胁迫的代谢调控网络的研究进展远远落后于相关分子机制的探究。海棠即为观赏树木又是苹果或其他海棠的砧木，本项目以耐盐能力不同的珠美海棠、山定子和平邑甜茶为材料，基于本课题组在植物代谢组和代流量组学的研究经验，从自然变异和化学诱导入手，利用13C-非稳态代谢流量分析方法(13C-INST-MFA)精准量化盐胁迫下初生和次生代谢内所有关键通路的流量，结合其他代谢组分析方法包括靶向代谢谱分析，逐层剖析代谢网络在盐胁迫下如何通过协同调节上下游反应来有效分配碳源、还原力以及能量物质并维持三者之间的动态平衡，系统阐述代谢在盐胁迫中所行使的核心调控功能，特异性的建立“代谢网络调控-代谢流量-耐盐机制”间的关系，寻找与盐胁迫下植物整株发育和生物量积累相关的代谢瓶颈，为利用代谢工程提高海棠耐盐性以及海棠耐盐性遗传改良提供深层次理论依据。

Plant metabolism deploys complex changes in response to saline-alkaline stress. Progress in metabolic regulation of salt tolerance has been limited by our lack of quantitative understanding of primary and secondary metabolism. Indeed, among the greatest challenges associated with breeding salt-tolerant horticultural crops is enriching our knowledge about the metabolic network in abiotic stress responses, which lags far behind its molecular mechanism. Malus spp., as both ornamental plants and apple rootstocks, are distinct, valuable horticultural crops in China. This project is first to investigate the natural variation of metabolic traits responding to salt stress using Malus spp. with different salt resistance capacity such as Malus zumi., Malus baccata Borkh., and Malus hupenensis Rhed. And then, this project is to assess the metabolic responses of Malus hupenensis Rhed. to chemical priming agents such as H2S. Based on the findings, we plan to perform in vivo 13C transient labeling of Malus spp. seedlings treated with salt stress or H2S and estimate fluxes throughout leaf primary and secondary metabolism via 13C-isotopically nonstationary metabolic flux analysis (13C-INST-MFA), which is a rigorous tool to quantify leaf metabolism. Our group have developed a package of MATLAB routines - INCA that automates the computational workflow of INST-MFA to map the flow of carbon through intracellular biochemical pathways. Combined with targeted metabolite profiling, this investigation is aiming to establish an integrated platform for quantifying network regulation of salt tolerance at cellular and subcellular levels. Also, we will develop quantitative biochemical descriptions of the carbon, nitrogen, redox and energy flows necessary to generate biomass in Malus spp. which can be the metabolic basis of salt resistance. The ultimate goal of this project is to specifically build a connection between regulatory metabolic network, metabolic fluxes, and salt tolerance. This is critical for identifying metabolic bottlenecks in biological systems related to yield penalty under salt stress. Taken together, these quantitative studies will provide a more “systems level” understanding of salt tolerance that in turn guides further rounds of metabolic engineering.