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Article|01 Apr 2021|OPEN
The role of γ-aminobutyric acid in aluminum stress tolerance in a woody plant, Liriodendron chinense × tulipifera
Pengkai Wang1,2, Yini Dong1, Liming Zhu1, Zhaodong Hao1, Lingfeng Hu1, Xiangyang Hu3, Guibin Wang4, Tielong Cheng5, Jisen Shi 1 & Jinhui Chen1,
1Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education of China, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
2Suzhou Polytechnic Institute of Agriculture, Suzhou 215008, China
3Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
4College of Forestry, Nanjing Forestry University, Nanjing 210037, China
5College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China

Horticulture Research 8,
Article number: 80 (2021)
doi: 10.1038/hortres.2021.80
Views: 221

Received: 20 Jul 2020
Revised: 01 Feb 2021
Accepted: 06 Feb 2021
Published online: 01 Apr 2021

Abstract

The aluminum (Al) cation Al3+ in acidic soil shows severe rhizotoxicity that inhibits plant growth and development. Most woody plants adapted to acidic soils have evolved specific strategies against Al3+ toxicity, but the underlying mechanism remains elusive. The four-carbon amino acid gamma-aminobutyric acid (GABA) has been well studied in mammals as an inhibitory neurotransmitter; GABA also controls many physiological responses during environmental or biotic stress. The woody plant hybrid Liriodendron (L. chinense × tulipifera) is widely cultivated in China as a horticultural tree and provides high-quality timber; studying its adaptation to high Al stress is important for harnessing its ecological and economic potential. Here, we performed quantitative iTRAQ (isobaric tags for relative and absolute quantification) to study how protein expression is altered in hybrid Liriodendron leaves subjected to Al stress. Hybrid Liriodendron shows differential accumulation of several proteins related to cell wall biosynthesis, sugar and proline metabolism, antioxidant activity, cell autophagy, protein ubiquitination degradation, and anion transport in response to Al damage. We observed that Al stress upregulated glutamate decarboxylase (GAD) and its activity, leading to increased GABA biosynthesis. Additional GABA synergistically increased Al-induced antioxidant enzyme activity to efficiently scavenge ROS, enhanced proline biosynthesis, and upregulated the expression of MATE1/2, which subsequently promoted the efflux of citrate for chelation of Al3+. We also showed similar effects of GABA on enhanced Al3+ tolerance in Arabidopsis. Thus, our findings suggest a function of GABA signaling in enhancing hybrid Liriodendron tolerance to Al stress through promoting organic acid transport and sustaining the cellular redox and osmotic balance.