Calcium involved in the poly(γ-glutamic acid)-mediated promotion of Chinese cabbage nitrogen metabolism.
Plant growth can reportedly be promoted by poly(γ-glutamic acid) (γ-PGA). However, the underlying mechanism is unknown. To reveal the mechanism of γ-PGA, we designed an experiment that investigated the effect of γ-PGA on the nitrogen metabolism of Chinese cabbage hydroponic cultured at different calcium (Ca) levels and varied exogenous Ca(2+) inhibitors. The results showed that nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase, and glutamate dehydrogenase activities in leaves and roots were obviously enhanced by γ-PGA at the normal Ca(2+) level (4.0 mM). Meanwhile, γ-PGA increased the content of total nitrogen, soluble protein, and soluble amino acids in leaves. However, the promotional effect of γ-PGA on fresh weight weakened when Ca(2+) was inadequate. Moreover, γ-PGA not only induced the influx of extracellular Ca(2+) and Ca(2+) in organelles into cytoplasm, but also increased the Ca(2+)-ATPase level to modify Ca(2+) homeostasis in plant cells. In addition, exogenous Ca(2+) inhibitors significantly suppressed the γ-PGA-mediated promotion of cytoplasmic free Ca(2+) level, calmodulin (CaM) content, GS and glutamate dehydrogenase activities. In summary, γ-PGA accelerated the nitrogen metabolism of plants through the Ca(2+)/CaM signaling pathway, thereby improving the growth of the plant.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China.
Zongqi
Z
Xu
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China.
Peng
P
Lei
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China; Nanjing Xuankai Bio-Technology Co., Ltd., Nanjing 211816, PR China. Electronic address: fengxiaohai@njtech.edu.cn.
Xiaohai
X
Feng
Institute of Agricultural Resource and Environmental Sciences, Jiangsu Academy of Agricultural Sciences, 210014, PR China.
Xianju
X
Xu
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China; Nanjing Xuankai Bio-Technology Co., Ltd., Nanjing 211816, PR China.
Jinfeng
J
Liang
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China.
Bo
B
Chi
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China; College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 211816, PR China; Nanjing Xuankai Bio-Technology Co., Ltd., Nanjing 211816, PR China. Electronic address: xuh@njtech.edu.cn.
Hong
H
Xu
D001937:Brassica / Q000187:drug effects* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D005970:Glutamate Synthase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D050901:Nitrate Reductase / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D005970:Glutamate Synthase; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; D002118:Calcium
Calcium; Chinese cabbage; Nitrogen metabolism; Poly(γ-glutamic acid); Subcellular compartments