MYB61 is regulated by GRF4 and promotes nitrogen utilization and biomass production in rice

Yihong Gao,Shaogan Wang,Zuopeng Xu,Dali Zeng,Baocai Zhang,Lanjun Zhang,Qiaoquan Liu,Hanlei Yang,Qian Qian,Xiangling Liu,Shance Li,Yihua Zhou

doi:10.1038/s41467-020-19019-x

Abstract

Nitrogen (N) is a macronutrient that boosts carbon (C) metabolism and plant growth leading to biomass accumulation. The molecular connection between nitrogen utilization efficiency (NUE) and biomass production remains unclear. Here, via quantitative trait loci analysis and map-based cloning, we reveal that natural variation at the MYB61 locus leads to differences in N use and cellulose biogenesis between indica and japonica subspecies of rice. MYB61, a transcriptional factor that regulates cellulose synthesis, is directly regulated by a known NUE regulator GROWTH-REGULATING FACTOR4 (GRF4), which coordinates cellulosic biomass production and N utilization. The variation at MYB61 has been selected during indica and japonica domestication. The indica allele of MYB61 displays robust transcription resulting in higher NUE and increased grain yield at reduced N supply than that of japonica. Our study hence unravels how C metabolism is linked to N uptake and may provide an opportunity to reduce N use for sustainable agriculture.

Highlights

Nitrogen (N) is a macronutrient that boosts carbon (C) metabolism and plant growth leading to biomass accumulation
As biomass production is an intuitive performance of nitrogen utilization efficiency (NUE), biomass increment of each unit of added N fertilizer that was higher in the indica accessions than in the japonica accessions (Fig. 1d) further suggested the existence of high NUE in indica subspecies
Plants uptake N from soils and fix CO2 from atmosphere; both elements are converted into diverse metabolites through C and N (C&N) metabolisms that are balanced via an elaborate coordination machinery

Summary

Introduction

Nitrogen (N) is a macronutrient that boosts carbon (C) metabolism and plant growth leading to biomass accumulation. N by plants is in accordance with its importance in producing nucleotides, proteins, chlorophyll, and numerous cellular components, which support fixation of carbon dioxide (CO2) to generate sugars, organic acids, and storage carbohydrates[1,2,3] All those building blocks sustain plant growth and accumulate as biomass. Arabidopsis nitrate transporters that show varied affinity to nitrate (e.g. NRT1, NRT2) play important roles in N uptake[14,15], which seem to act as N sensors required for C assimilation[10,16,17] Another level for C&N coordination is via signaling and transcriptional regulation. There are approximately 56 × 109 metric tons of net CO2 being fixed by land plants per year[27]; more than 70% of the CO2 assimilated products are converted into polysaccharides, referred to as cell wall polysaccharides, to build the plants themselves[28,29]

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Conclusion