Table_1_Merging the occurrence possibility into gene co-expression network deciphers the importance of exogenous 2-oxoglutarate in improving the growth of rice seedlings under thiocyanate stress.doc

Thiocyanate (SCN−) can find its way into cultivated fields, which might hamper the harmony in carbon and nitrogen metabolism (CNM) of plants, ebbing their quality and productivity. In the current study, we investigated the role of the exogenous application of 2-oxoglutarate (2-OG) in maintaining homeostasis of CNM in rice seedlings under SCN− stress. Results showed that SCN− exposure significantly repressed the gene expression and activities of CNM-related enzymes (e.g., phosphoenolpyruvate carboxylase, NADP-dependent isocitrate dehydrogenases, and isocitrate dehydrogenases) in rice seedlings, thereby reducing their relative growth rate (RGR). Exogenous application of 2-OG effectively mitigated the toxic effects of SCN− on rice seedlings, judged by the aforementioned parameters. The co-expression network analysis showed that genes activated in CNM pathways were categorized into four modules (Modules 1–4). In order to identify the key module activated in CNM in rice seedlings exposed to SCN−, the results from real-time quantitative PCR (RT-qPCR) tests were used to calculate the possibility of the occurrence of genes grouped in four different modules. Notably, Module 3 showed the highest occurrence probability, which is mainly related to N metabolism and 2-OG synthesis. We can conclude that exogenous application of 2-OG can modify the imbalance of CNM caused by SCN− exposure through regulating N metabolism and 2-OG synthesis in rice seedlings.

硫氰酸盐（Thiocyanate，SCN⁻）可进入农田，可能破坏植物碳氮代谢（Carbon and Nitrogen Metabolism，CNM）的稳态平衡，降低其品质与生产能力。本研究探究了外源施加2-氧戊二酸（2-oxoglutarate，2-OG）对硫氰酸盐胁迫（SCN⁻ stress）下水稻幼苗碳氮代谢稳态的维持作用。结果显示，硫氰酸盐暴露会显著抑制水稻幼苗碳氮代谢相关酶，如磷酸烯醇式丙酮酸羧化酶（phosphoenolpyruvate carboxylase）、NADP依赖型异柠檬酸脱氢酶（NADP-dependent isocitrate dehydrogenases）及异柠檬酸脱氢酶（isocitrate dehydrogenases）的基因表达与酶活性，进而降低其相对生长速率（Relative Growth Rate，RGR）。基于上述观测指标，外源施加2-OG可有效缓解硫氰酸盐对水稻幼苗的毒害作用。共表达网络分析（co-expression network analysis）表明，碳氮代谢通路中的激活基因可分为4个模块（模块1至模块4）。为筛选硫氰酸盐胁迫下水稻幼苗碳氮代谢激活的关键模块，本研究通过实时荧光定量聚合酶链式反应（Real-time Quantitative PCR，RT-qPCR）的检测结果，计算了4个模块中各基因的出现概率。值得注意的是，模块3的出现概率最高，其主要与氮代谢（Nitrogen metabolism）及2-OG合成相关。综上，外源施加2-OG可通过调控水稻幼苗的氮代谢与2-OG合成，改善硫氰酸盐暴露引发的碳氮代谢失衡。