Jianyun Yue1, Changjian Du1, Jing Ji1, Tiantian Xie1, Wei Chen1, Ermei Chang1, Lanzhen Chen2,3, Zeping Jiang4,5, Shengqing Shi6. 1. State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, No. 1 Dongxiaofu, Xiangshan Road, Haidian, Beijing, 100091, China. 2. Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China. 3. Risk Assessment Laboratory for Bee Products, Quality and Safety of Ministry of Agriculture, Beijing, China. 4. State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, No. 1 Dongxiaofu, Xiangshan Road, Haidian, Beijing, 100091, China. jiangzp@caf.ac.cn. 5. Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, China. jiangzp@caf.ac.cn. 6. State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, No. 1 Dongxiaofu, Xiangshan Road, Haidian, Beijing, 100091, China. shi.shengqing@caf.ac.cn.
Abstract
MAIN CONCLUSION: Blocking α-ketoglutarate dehydrogenase results in up-regulation of γ-aminobutyric acid (GABA) shunt activity, and inhibits the growth of poplar adventitious roots (ARs), indicating that AR growth is closely associated with GABA shunt. γ-Aminobutyric acid (GABA) shunt starts from α-ketoglutarate in the tricarboxylic acid cycle, which is thought to represent the cross road between carbon and nitrogen metabolism. Previous studies (Araújo et al. 2012b, Plant Cell 24: 2328-2351) have shown that blocking α-ketoglutarate dehydrogenase (α-KGDH) affects the GABA shunt activity, and inhibits growth. However, its effects on the growth of adventitious roots (ARs) are unclear. In this study, the growth of ARs in tissue-cultured 84K poplar (Populus alba × Populus glandulosa cv. '84K') was significantly inhibited when succinyl phosphate (SP), a specific inhibitor of α-KGDH, was supplied. The inhibition of ARs was associated with significant changes in the levels of soluble sugars, organic acids, and amino acids, and was coupled with the up-regulation of the GABA shunt activity at the transcriptional and translational levels. Exogenous GABA also inhibited AR growth following the increase of the endogenous GABA level. Transcriptomic analyses further showed that genes related to cell wall carbon metabolism and phytohormone (indoleacetic acid, ABA, and ethylene) signaling were affected by the changes of GABA shunt activity, resulting from the α-KGDH inhibition. Thus, our study indicates that the inhibition of poplar AR growth by blocking α-KGDH is closely associated with GABA shunt, which would benefit a better understanding of GABA's roles in plant development and stress response.
MAIN CONCLUSION: Blocking α-ketoglutarate dehydrogenase results in up-regulation of γ-aminobutyric acid (GABA) shunt activity, and inhibits the growth of poplar adventitious roots (ARs), indicating that AR growth is closely associated with GABA shunt. γ-Aminobutyric acid (GABA) shunt starts from α-ketoglutarate in the tricarboxylic acid cycle, which is thought to represent the cross road between carbon and nitrogen metabolism. Previous studies (Araújo et al. 2012b, Plant Cell 24: 2328-2351) have shown that blocking α-ketoglutarate dehydrogenase (α-KGDH) affects the GABA shunt activity, and inhibits growth. However, its effects on the growth of adventitious roots (ARs) are unclear. In this study, the growth of ARs in tissue-cultured 84K poplar (Populus alba × Populus glandulosa cv. '84K') was significantly inhibited when succinyl phosphate (SP), a specific inhibitor of α-KGDH, was supplied. The inhibition of ARs was associated with significant changes in the levels of soluble sugars, organic acids, and amino acids, and was coupled with the up-regulation of the GABA shunt activity at the transcriptional and translational levels. Exogenous GABA also inhibited AR growth following the increase of the endogenous GABA level. Transcriptomic analyses further showed that genes related to cell wall carbon metabolism and phytohormone (indoleacetic acid, ABA, and ethylene) signaling were affected by the changes of GABA shunt activity, resulting from the α-KGDH inhibition. Thus, our study indicates that the inhibition of poplar AR growth by blocking α-KGDH is closely associated with GABA shunt, which would benefit a better understanding of GABA's roles in plant development and stress response.
Entities:
Keywords:
Carbon metabolism; Hormones; Signal transduction; α-KGDH; γ-aminobutyric acid
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