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在营养液中添加硝态氮模拟设施白菜(Brassica campestris ssp.chinensis Makino)生产中氮肥施用量,采用5、10 mmol·L~(-1)γ–氨基丁酸(GABA)浸泡种子,研究GABA对白菜生长以及硝酸盐代谢过程中物质含量和关键酶活性、基因表达和蛋白表达的影响。结果表明:与对照和未经GABA浸种的高氮处理相比,GABA浸种显著促进了高氮条件下白菜的生长,并通过显著提高叶片硝酸还原酶(NR)、亚硝酸还原酶(NiR)、谷氨酸脱羧酶(GAD)等关键酶活性以及NR、GAD基因和蛋白表达量,诱导硝酸盐、亚硝酸盐含量显著降低,但铵态氮(NH_4~+-N)、谷氨酸(Glu)和内源GABA含量仍维持较高水平。进一步分析表明,GABA浸种降低硝酸盐的效果存在时效性和浓度差异,在高氮处理0~12 d时效果较明显,5 mmol·L~(-1) GABA处理效果较好;并且GABA对NR、GAD基因、蛋白表达的影响早于酶活性的变化。结果证明GABA浸种在促进植株生长的同时,通过提高叶片NR、GAD等代谢关键酶的活性、基因和蛋白表达量,加速了无机氮的还原和同化,从而降低叶片硝酸盐含量,提高白菜的产量和品质。
The amount of nitrogen fertilizer used in the production of Brassica campestris ssp.chinensis Makino was added into the nutrient solution and the seeds were soaked with 5 and 10 mmol·L -1 γ-aminobutyric acid (GABA) to study the effects of GABA On the growth of Chinese cabbage and the content of nitric oxide and its key enzyme activities, gene expression and protein expression. The results showed that the soaking of GABA significantly promoted the growth of Chinese cabbage under high nitrogen conditions compared with the control and the high nitrogen treatment without GABA soaking, and significantly increased the contents of nitrate reductase (NR), nitrite reductase (NiR) GAD and other key enzyme activities as well as the expression of NR and GAD genes and proteins, and significantly decreased the contents of nitrate and nitrite. However, the contents of NH 4 + -N and Glu ) And endogenous GABA levels remained high. Further analysis showed that there was a time-effect and concentration difference in the effect of GABA soaking nitrite, and the effect was obvious at 0-12 d of high nitrogen treatment and 5 mmol·L -1 of GABA. The effect of GABA on NR The effect of GAD gene and protein expression was earlier than that of enzyme activity. The results showed that GABA soaking promoted the growth of plants and increased the activity of key enzymes such as NR and GAD, the expression of genes and proteins, accelerated the reduction and assimilation of inorganic nitrogen, reduced the nitrate content in leaves and increased the yield of cabbage And quality.