Comparative Study on Metabolites and Elements of Two Dominant Plant Communities in Saline-Alkali Grassland

The aggravation of soil salinization and alkalization has resulted in the increase of diversity and succession among plant communities. In order to explore the adaptive strategy of the communities in such ecosystem, this study employed contrastive analysis on metabolites and mineral elements differences between two dominant communities in the study area, namely Puccinellia tenuiflora community (PC) and Suaeda glauca community (SC), the community succession of which was previously reported. The community succession (PC-*SC) represented deteriorative saline-alkali grassland. As a result, little distinction was revealed in terms of element levels. Specifically, only Ca level increased in SC stem compared with that of PC, while Fe levels in root decreased. On the other hand, major difference of metabolite results appeared in leaf. Increased sugar alcohols and decreased sugars were observed in leaf of SC comparing to PC. Importantly, most organic acids involved in TCA cycle, photorespiration, redox reactions and glycolysis accumulated significantly, which possibly suggests an enhancement in the flow of carbon from glycolysis to TCA cycle. In addition, the variation of a few phenols, such as reduced phenylpropanoids, may have promoted the metabolism of organic acid. Combined with the analysis of correlation-based network, it illustrates that central metabolism shifted from nitrogen metabolism to organic acid metabolism in community succession (PC-*SC).