外源蔗糖对高NH4+胁迫下拟南芥碳氮代谢的影响

以拟南芥野生型、amt1.1和amt1.3为实验材料，采取土培的方法，以正常培养液（4mmol/L NH4+）培养，在20mmol/L NH4+的胁迫下，通过在培养液中添加0%（T1）蔗糖、5%（T2）蔗糖，测定地上部分的鲜重，叶绿素，游离NH4+，可溶性糖，可溶性蛋白，谷氨酰胺合成酶（GS）、谷氨酸脱氢酶（GDH），矿质元素含量等指标，研究外源蔗糖对NH4+胁迫拟南芥碳氮代谢的影响。结果表明，T1处理下，拟南芥生长受到严重的抑制，鲜重，GS，GDH酶活性降低，游离NH4+含量，叶绿素含量，可溶性糖和可溶性蛋白含量增加，植株的N、P、K、Ca的含量增加，Mg、Fe的含量减少。其中col-0在T1处理下受到的抑制比amt1.1和amt1.3更为显著。与T1处理相比较，T2处理增加了拟南芥植株的鲜重，显著提高了可溶性糖和可溶性蛋白含量，提高了GS和GDH的活性；降低了叶绿素和游离NH4+的含量，提高了植株体内的N、P、K、Ca，Mg的含量，降低了植株Fe的含量，其中，外源蔗糖对col-0高NH4+毒害的缓解更为显著。

Effect of Exogenous Sucrose on Nitrogen and Carbon Metabolism of Arabidopsis Under High NH4+ Stress

Arabidopsis col-0,amt1.1 and amt1.3 were used as materials. By adding 0% (T1) or 5% (T2) sucrose to the culture solution, the influences of exogenous sucrose on nitrogen and carbon metabolism of three Arabidopsis lines in nutrient solution under 20 mmol/L NH₄⁺ were investigated. Plants grown under 4 mmol/L NH₄⁺ were used as controls (CK). The fresh weight, the contents of chlorophyll, NH₄⁺- N, soluble sugar and protein, the activity of glutamine synthetase (GS) and glutamate dehydrogenase (GDH), the mineral element contents of aboveground parts of Arabidopsis were determined in this study. The results showed that, the growth of three Arabidopsis lines was significantly restrained under 20 mmol/L NH₄⁺ condition (T1) compared with 4 mmol/L NH₄⁺ (CK). With the increasing of NH₄⁺ concentration, the fresh weight and the GS and GDH activities were reduced, but the contents of NH₄⁺, chlorophyll, soluble sugar, soluble proteins, N, P, K and Ca of Arabidopsis were increased, while the contents of Mg and Fe of Arabidopsis were reduced. Compared with amt1.1 and amt1.3, col-0 was more sensitive to high NH₄⁺. Compared with T1 treatment, T2 treatment increased the fresh weight of Arabidopsis, significantly increased the contents of soluble sugar and protein, enhanced the activities of GS and GDH, reduced the contents of ammonium and chlorophyll of Arabidopsis, increased the contents of N, P, K, Ca and Mg but reduced the content of Fe in Arabidopsis. Compared with amt1.1 and amt1.3, exogenous addition of sucrose (T2) showed a better alleviation effect on high NH₄⁺-stress in Col-0.