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Exogenous GABA promotes adaptation and growth by altering the carbon and nitrogen metabolic flux in poplar seedlings under low nitrogen conditions.
Tree Physiology ( IF 4 ) Pub Date : 2020-08-08 , DOI: 10.1093/treephys/tpaa101
Wei Chen 1 , Chen Meng 2 , Jing Ji 1 , Mai-He Li 3, 4, 5 , Xiaoman Zhang 6 , Yanyan Wu 1 , Tiantian Xie 1 , Changjian Du 1 , Jiacheng Sun 1 , Zeping Jiang 7 , Shengqing Shi 1
Affiliation  

Nitrogen (N) deficiency adversely affects tree growth. Additionally, γ-aminobutyric acid (GABA) is closely associated with growth and stress responses because of its effects on carbon (C) and N metabolism. However, little is known about its roles related to plant adaptations to N-deficient conditions. In this study, we analyzed the effects of GABA (0, 2, and 10 mM) applications on the growth traits and physiological responses of poplar (Populus alba × Populus glandulosa ‘84 K’) seedlings under high N (HN) and low N (LN) conditions. We found that the added GABA interacted with N to affect more than half of the studied parameters, with greater effects in LN plants than in HN plants. Under LN conditions, the GABA application tended to increase poplar growth, accompanied by increased xylem fiber cell length and xylem width. In stems, exogenous GABA increased the abundance of non-structural carbohydrates (starch and sugars) and tricarboxylic acid cycle intermediates (succinate, malate, and citrate), but had the opposite effect on the structural C contents (hemicellulose and lignin). Meanwhile, exogenous GABA increased the total soluble protein contents in leaves and stems, accompanied by significant increases in nitrate reductase, nitrite reductase, and glutamine synthetase activities in leaves, but significant decreases in those (except for the increased glutamate synthetase activity) in stems. A multiple factorial analysis indicated that the nitrate assimilation pathway substantially influences poplar survival and growth in the presence of GABA under LN conditions. Interestingly, GABA applications also considerably attenuated the LN-induced increase in the activities of leaf antioxidant enzymes, including peroxidase and catalase, implying that GABA may regulate the relative allocation of C and N for growth activities by decreasing the energy cost associated with stress defense. Our results suggest that GABA enhances poplar growth and adaptation by regulating the C and N metabolic flux under N-deficient conditions.

中文翻译:

外源GABA通过改变低氮条件下杨树幼苗的碳和氮代谢通量来促进适应和生长。

氮缺乏对树木的生长有不利影响。此外,γ-氨基丁酸(GABA)由于对碳(C)和N代谢有影响,因此与生长和应激反应密切相关。然而,关于其与植物适应氮不足条件有关的作用知之甚少。在这项研究中,我们分析了GABA(0、2和10 mM)施用对白杨(Populus alba × Populus glandulosa)生长特性和生理响应的影响高氮(HN)和低氮(LN)条件下的'84 K')幼苗。我们发现,添加的GABA与N相互作用会影响一半以上的研究参数,与LN植物相比,LN植物的影响更大。在LN条件下,GABA的施用倾向于增加杨树的生长,并伴随着木质部纤维细胞长度和木质部宽度的增加。在茎中,外源GABA增加了非结构性碳水化合物(淀粉和糖)和三羧酸循环中间体(琥珀酸盐,苹果酸和柠檬酸盐)的含量,但对结构C含量(半纤维素和木质素)的作用却相反。同时,外源GABA增加了叶片和茎中总可溶性蛋白质含量,并伴随着叶片中硝酸盐还原酶,亚硝酸盐还原酶和谷氨酰胺合成酶活性的显着增加,但茎中的氨基酸含量显着降低(除了谷氨酸合成酶活性增加)。多因素分析表明,在LN条件下,存在GABA时,硝酸盐同化途径会显着影响杨树的存活和生长。有趣的是,GABA的应用还大大减弱了LN诱导的叶片抗氧化剂酶(包括过氧化物酶和过氧化氢酶)活性的增加,这暗示GABA可以通过降低与胁迫防御相关的能量成本来调节C和N相对分配用于生长活动。我们的结果表明,GABA通过在缺氮条件下调节C和N代谢通量来增强杨树的生长和适应能力。多因素分析表明,在LN条件下,存在GABA时,硝酸盐同化途径会显着影响杨树的存活和生长。有趣的是,GABA的应用还大大减弱了LN诱导的叶片抗氧化剂酶(包括过氧化物酶和过氧化氢酶)活性的增加,这暗示GABA可以通过降低与胁迫防御相关的能量成本来调节C和N相对分配用于生长活动。我们的结果表明,GABA通过在缺氮条件下调节C和N代谢通量来增强杨树的生长和适应能力。多因素分析表明,在LN条件下,存在GABA时,硝酸盐同化途径会显着影响杨树的存活和生长。有趣的是,GABA的应用还大大减弱了LN诱导的叶片抗氧化剂酶(包括过氧化物酶和过氧化氢酶)活性的增加,这暗示GABA可以通过降低与胁迫防御相关的能量成本来调节C和N相对分配用于生长活动。我们的结果表明,GABA通过在氮缺乏条件下调节C和N代谢通量来增强杨树的生长和适应能力。GABA的应用还大大减弱了LN诱导的叶片抗氧化剂酶(包括过氧化物酶和过氧化氢酶)活性的增加,这暗示GABA可以通过降低与胁迫防御相关的能量成本来调节生长活动中C和N的相对分配。我们的结果表明,GABA通过在缺氮条件下调节C和N代谢通量来增强杨树的生长和适应能力。GABA的应用还大大减弱了LN诱导的叶片抗氧化剂酶(包括过氧化物酶和过氧化氢酶)活性的增加,这暗示GABA可以通过降低与胁迫防御相关的能量成本来调节生长活动中C和N的相对分配。我们的结果表明,GABA通过在缺氮条件下调节C和N代谢通量来增强杨树的生长和适应能力。
更新日期:2020-08-10
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