Nitrate reutilization mechanisms in the tonoplast of two Brassica napus genotypes with different nitrogen use efficiency

Yongliang Han, Qiong Liao, Yin Yu, Haixing Song*, Qiang Liu, Xiangmin Rong, Jidong Gu, Joe Eugene Lepo, Chunyun Guan, Zhenhua Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Nitrate (NO3 ) can accumulate in high concentrations in plant cell vacuoles if it is not reduced, reutilized or transported into the cytoplasm. Such accumulation of NO3 in the vacuole occurs when mechanisms for NO3 assimilation in the cytoplasm are saturated. Moreover, other processes such as efflux across the plasma membrane might affect NO3 accumulation in the vacuole. These are the main reasons limiting nitrogen use efficiency (NUE) in plants. This study elucidates mechanisms for NO3 transport from the cytoplasm to vacuoles by the V-proton pump (V-ATPase and V-PPase) and their relationship with different NUE in four Brassica napus genotypes. Pot experiments were conducted in a greenhouse under normal (15.0 mmol L−1) and limited N (7.5 mmol L−1) concentrations of nitrate using B. napus genotypes that demonstrated either high (742 and Xiangyou 15) or low (814 and H8) NUE (g g−1). Specific inhibitors of V-ATPase and V-PPase increased nitrate reductase (NR) activity, resulting in greatly decreased NO3 in plant tissues. Nitrate reductase activity and NO3 content correlated more highly to V-PPase activity than they did to V-ATPase activity, and correlation between V-PPase activity and NO3 content was significantly higher than it was to V-ATPase. Genotypes with high NUE had significantly lower activities of V-ATPase and V-PPase than those with low NUE. In the high-NUE plants, lower activities of V-proton pump underlie mechanisms that result in significantly lower NO3 content in plant tissues of the high-NUE genotypes than those found in plant tissues of the low-NUE genotypes. Our results show that the tonoplast proton pumps V-PPase and V-ATPase strongly negatively affect NR activity and positively affect NO3 content. V-PPase contributed more to this regulatory mechanism than did V-ATPase.

Original languageEnglish
Article number42
JournalActa Physiologiae Plantarum
Issue number2
StatePublished - Feb 2015
Externally publishedYes


  • N reutilization
  • N use efficiency
  • Oilseed rape (Brassica napus)
  • Proton pumps in the tonoplast


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