Journal Article

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

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

2015

Overview

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.

• Publisher: Springer-Verlag,Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Accumulation / Adenosine triphosphatase / Agricultural production / Agriculture / Biomass / Biomedical and Life Sciences / Brassica / Brassica napus / Crops / Cytoplasm / Efficiency / Efflux / genotype / Genotypes / greenhouses / H+-transporting ATPase / H-transporting ATP synthase / Life Sciences / Metabolism / Nitrate reductase / Nitrates / Nitrogen / nutrient use efficiency / Oilseeds / Original Paper / Physiology / Plant Anatomy/Development / Plant Biochemistry / Plant Genetics and Genomics / Plant Pathology / Plant Physiology / Plant tissues / plasma membrane / proton pump / Protons / Rape plants / Reductases / tonoplast / Vacuoles