Metabolic responses to drought stress in the tissues of drought-tolerant and drought-sensitive wheat genotype seedlings

AoB PLANTS, Mar 2018

Guo, Rui, Shi, LianXuan, Jiao, Yang, Li, MingXia, Zhong, XiuLi, Gu, FengXue, Liu, Qi, Xia, Xu, Li, HaoRu

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Metabolic responses to drought stress in the tissues of drought-tolerant and drought-sensitive wheat genotype seedlings

Metabolic responses to drought stress in the tissues of drought-tolerant and drought-sensitive wheat genotype seedlings Rui Guo 1 LianXuan Shi 0 Yang Jiao 0 MingXia Li 0 XiuLi Zhong 1 FengXue Gu 1 Qi Liu 1 Xu Xia 1 HaoRu Li 1 Associate Editor: Wen-Hao Zhang 0 School of Life Sciences, Northeast Normal University , Changchun 130024 , China 1 Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS)/Key Laboratory of Dryland Agriculture, Ministry of Agriculture , Beijing 100081 , P.R. China An in-depth understanding of the effects of drought stress on plant metabolism is necessary to improve the drought tolerance of wheat and to utilize genetic resources for the development of drought stress-tolerant wheat varieties. In this study, the profiles of 58 key metabolites produced by wheat seedlings in response to drought stress were investigated to determine various physiological processes related to drought tolerance between drought-tolerant and drought-sensitive wheat genotypes. Results showed that the wheat metabolome was dominated by sugars, organic acids and amino acids; the wheat metabolome played important roles to enhance the drought tolerance of shoots. Under drought stress, JD17 exhibited higher growth indices and higher photosynthesis ability than JD8. A  high level of compatible solutes and energy in shoots were essential for wheat to develop drought tolerance. Drought also caused system alterations in widespread metabolic networks involving transamination, tricarboxylic acid cycle, glycolysis, glutamate-mediated proline biosynthesis, shikimate-mediated secondary metabolisms and γ-aminobutyric acid metabolisms. Long-term drought stress resulted in the drought-tolerant wheat genotype JD17, which induced metabolic shifts in the tricarboxylic acid cycle and glycolysis with the depletion of the γ-aminobutyric acid shut process. In JD17, the prolonged drought stress induced a progressive accumulation of osmolytes, including proline, sucrose, fructose, mannose and malic acid. This research extended our understanding of the mechanisms involved in wheat seedling drought tolerance; this study also demonstrated that gas chromatography-mass spectrometry metabolomics could be an effective approach to understand the drought effects on plant biochemistry. Drought stress; growth; metabolites; photosynthesis indices; wheat Introduction Drought has affected humans since the emergence of agriculture and has caused the collapse of several civilizations (Stendle and Peterson 1998; Zhao et al. 2009) . Drought remains prevalent in the modern era; for instance, drought affected 1.13 × 107 hm2 of agricultural land in China in the 1970s and doubled to 2.667 × 107 hm2 in the 1990s. The effect of drought has been countered by developing water-saving agricultural practices based on engineering, agronomy and water management (Wang et al. 2002; Luis et al. 2012) . Biotechnology is in its infancy with regard to accelerating production of drought-tolerant crops (Shi 1999; Shao et  al. 2007; Plauborg et  al. 2010) . However, progress in this area is significantly hampered by the physiological and genetic complexity of the drought tolerance trait. Thus, an enhanced understanding of drought tolerance mechanisms is necessary to improve crop varieties. Drought is caused by insufficient water for uptake; this phenomenon inhibits further nutrient absorption and affects crop growth, gene expression, distribution, yield and quality (Stendle and Peterson 1998; Zhao et al. 2009) . To tolerate drought stress, plants have evolved adaptive mechanisms, including accumulation of high concentrations of compatible solutes in the cytoplasm to counteract drought stress (Egilla et  al. 2001; Chemikosova et  al. 2006) . Plant responses to drought stress may involve metabolic pathways, such as photosynthesis, sugar synthesis, tricarboxylic acid cycle, glycolysis and hormone synthesis (Spickett et  al. 1992; Hare et  al. 1998; Dennison et al. 2001) . Metabolomic solutes, such as proline, betaine, fructose and sucrose, contribute to drought stress tolerance (Chen and Murata 2002; Yasar et al. 2006; Wang et al. 2012) . Metabolomic components may also participate in plant drought tolerance; however, information regarding drought tolerance-related metabolomic components is limited. A  comparative metabolic analysis of the responses of drought-tolerant genotypes and drought-sensitive genotypes to drought stress should be conducted to determine the mechanisms related to drought stress adaptation and to understand plant drought tolerance (Abebe et  al. 2003; Miller et  al. 2010) . Metabolomic analyses have been applied to examine the abiotic stress tolerance of plants; these analyses can determine the specific responses of biological systems to genetic and environmental changes (Renberg et al. 2010; Oliver et al. 2011) . Metabolomic analyses include various approaches, such as (...truncated)


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Guo, Rui, Shi, LianXuan, Jiao, Yang, Li, MingXia, Zhong, XiuLi, Gu, FengXue, Liu, Qi, Xia, Xu, Li, HaoRu. Metabolic responses to drought stress in the tissues of drought-tolerant and drought-sensitive wheat genotype seedlings, AoB PLANTS, 2018, Volume 10, Issue 2, DOI: 10.1093/aobpla/ply016