外源Spd对盐碱胁迫下番茄幼苗氮代谢及主要矿质元素含量的影响

Effects of exogenous spermidine on the nitrogen metabolism and main mineral elements contents of tomato seedlings under saline-alkali stress.

采用水培方法,研究了盐碱与Spd处理对两品种番茄(中杂9号和金棚朝冠)幼苗氮代谢及主要矿质元素含量的影响.结果表明:盐碱胁迫下,番茄幼苗干生物量显著减少,植株生长受到抑制;叶片和根系硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)活性及硝态氮(NO_3^--N)、全N、全K、Ca^(2+)、Mg^(2+)含量显著降低,铵态氮(NH_4^+-N)、Na^+含量显著增加;两品种叶片及中杂9号根系谷氨酸脱氢酶(GDH)活性显著升高,金棚朝冠根系GDH活性变化不显著;叶片全P含量显著降低,根系全P含量显著升高(金棚朝冠)或无显著变化(中杂9号).Spd处理通过增强NR、GS、GOGAT活性提高了植株对NH_4^+的同化利用率,有效缓解了盐碱胁迫导致的氮代谢紊乱,进而促进不同器官对P、K、Ca、Mg、Na的吸收、释放或转运,在一定程度上维持了各元素之间的相对平衡,从而增强植株对逆境的适应能力.此外,盐碱对中杂9号的抑制作用及外源Spd对其氮代谢紊乱和营养失衡的缓解作用高于金棚朝冠.

Taking two tomato euhivars Zhongza No. 9 and Jinpengehaoguan as test objects, a hydro- ponie experiment was conducted to study the effects of exogenous spermidine （Spd） on the tomato seedling nitrogen metabolism and main mineral elements contents under saline-alkali stress. Under the stress, the seedling dry biomass decreased significantly, and the plant growth was inhibited. The activities of nitrate reduetase （NR）, glutamine synthetase （GS）, and glutamate synthase （GOGAT） and the contents of nitrate nitrogen （NO3--N） and total N, K, Ca2＋, and Mg2＋ in leaves and roots decreased significantly, while the contents of ammonium nitrogen （NH4＋-N） , and Na＋ had a significant increase. The activity of glutamate dehydrogenase （GDH） in the leaves of the two euhivars and in the roots of Zhongza No. 9 increased significantly, but that in the roots of Jin- pengehaoguan had less change. The total P content in the leaves of the two eultivars decreased sig- nificantly, while that in the roots of Jinpengehaoguan and Zhongza No. 9 had a signifieant..inerease and less change, respectively. Applying exogenous Spd increased the assimilation of NH4 ＋ by the plants through increasing the NR, GS and GOGAT activities, alleviated the nitrogen metabolic dis- turbanee caused by the saline-alkali stress, and further, promoted the absorption, release, or transline-alkali stress than Jinpengchaoguan metabolic disturbance and nutritional , and the alleviation effect of exogenous Spd on the nitrogen out-of-balance of Zhongza No. 9 was more obvious