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Plant Physiol. 2019 Jun;180(2):882-895. doi: 10.1104/pp.19.00142. Epub 2019 Mar 18.

A Transcription Factor, OsMADS57, Regulates Long-Distance Nitrate Transport and Root Elongation.

Author information

1
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
2
Henan Key Laboratory of Tea Plant Comprehensive Utilization in South Henan, Xinyang Agriculture and Forestry University, Xinyang 464000, China.
3
College of Agronomy, Collaborative Innovation Center of Henan Grain Crops, Key Laboratory of Rice Biology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China.
4
Institute of Food Crops of Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
5
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China ylzhang@njau.edu.cn.

Abstract

Root nitrate uptake adjusts to the plant's nitrogen demand for growth. Here, we report that OsMADS57, a MADS-box transcription factor, modulates nitrate translocation from rice (Oryza sativa) roots to shoots under low-nitrate conditions. OsMADS57 is abundantly expressed in xylem parenchyma cells of root stele and is induced by nitrate. Compared with wild-type rice plants supplied with 0.2 mM nitrate, osmads57 mutants had 31% less xylem loading of nitrate, while overexpression lines had 2-fold higher levels. Shoot-root 15N content ratios were 40% lower in the mutants and 76% higher in the overexpression lines. Rapid NO3 - root influx experiments showed that mutation of OsMADS57 did not affect root nitrate uptake. Reverse transcription quantitative PCR analysis of OsNRT2 nitrate transporter genes showed that after 5 min in 0.2 mM nitrate, only OsNRT2.3a (a vascular-specific high-affinity nitrate transporter) had reduced (by two-thirds) expression levels. At 60 min of nitrate treatment, lower expression levels were also observed for three additional NRT2 genes (OsNRT2.1/2.2/2.4). Conversely, in the overexpression lines, four NRT2 genes had much higher expression profiles at all time points tested. As previously reported, OsNRT2.3a functions in nitrate translocation, indicating the possible interaction between OsMADS57 and OsNRT2.3a Yeast one-hybrid and transient expression assays demonstrated that OsMADS57 binds to the CArG motif (CATTTTATAG) within the OsNRT2.3a promoter. Moreover, seminal root elongation was inhibited in osmads57 mutants, which may be associated with higher auxin levels in and auxin polar transport to root tips of mutant plants. Taken together, these results suggest that OsMADS57 has a role in regulating nitrate translocation from root to shoot via OsNRT2.3a.

PMID:
30886113
PMCID:
PMC6548263
[Available on 2020-06-01]
DOI:
10.1104/pp.19.00142

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