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Glucose and Sucrose Supply Regulates the Uptake, Transport, and Metabolism of Nitrate in Pak Choi
Author(s) -
Ma Qingxu,
Ma Jinzhao,
Wang Jun,
Wang Qiong,
Feng Ying,
Wu Lianghuan
Publication year - 2018
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2017.09.0541
Subject(s) - nitrate , nitrate reductase , sucrose , nitrogen assimilation , chemistry , metabolism , shoot , glutamine synthetase , carbohydrate metabolism , biochemistry , agronomy , glutamine , horticulture , food science , biology , amino acid , organic chemistry
Core Ideas The optimal levels of glucose and sucrose for pak choi growth were 25 and 15 μM with 18 and 25% increase in pak choi biomass. The optimal glucose level reduced the uptake and N contribution of nitrate. The optimal glucose level decreased the nitrate transportation to shoots by reducing the NRT1.1 expression, while enhancing the nitrate assimilation ability.High nitrate content in vegetables is regarded as a serious threat to human health. The effects of exogenous sugars on the uptake, transportation, and assimilation of nitrate were studied with vitro grown pak choi. The optimal levels of glucose and sucrose for pak choi growth were 25 and 15 μM, respectively, which led to an increase in pak choi biomass by 18 and 25%, respectively. The uptake and N contribution of nitrate in pak choi grown under optimal glucose levels were significantly lower than those in pak choi grown without glucose. The optimal levels of both glucose and sucrose decreased the active nitrate uptake in roots. However, the optimal glucose level decreased the nitrate transportation to shoots by reducing the NRT1.1 expression, while enhancing the nitrate assimilation ability by increasing the activities of nitrate reductase (NR) and glutamine synthetase (GS) and the gene expression of Gln1 and Gln2 as compared to the pak choi grown under optimal sucrose level. Under optimal glucose levels, the nitrate content of pak choi decreased by 37%, improving its edible quality in the mixed nitrogen. We recommend supplying pak choi with optimal levels of exogenous glucose to reduce its nitrate content, and thus improve its edible quality.