2026-02-27 オックスフォード大学
＜関連情報＞
- https://www.ox.ac.uk/news/2026-02-27-rice-gene-discovery-could-cut-fertiliser-use-while-protecting-yields
- https://www.science.org/doi/10.1126/science.aeb8384
OsWRI1aはイネの窒素利用能に対する全身成長反応を調整する OsWRI1a coordinates systemic growth responses to nitrogen availability in rice
Chengbo Shen, Zhe Ji, Wu Jiao, Siyu Zhang, […] , and Shan Li
Science Published:26 Feb 2026
Editor’s summary
Nitrogen availability affects the balance of root versus shoot biomass in plants. Shen et al. identified a rice gene, OsWRI1a, which controls root and shoot growth in response to nitrogen (see the Perspective by Suganami and Matsuoka). In shoots, OsWRI1a activates regulators of branch growth, whereas in roots, it operates a feedback loop with ubiquitin ligase components affecting auxin accumulation. These tissue-specific interactions separate the regulatory processes of shoot and root growth in response to nitrogen levels and offer targets to uncouple these processes in crop breeding or genetic editing. —Madeleine Seale
Structured Abstract
INTRODUCTION
Plants have evolved the ability to optimize resource allocation, enabling adaptive development under environments with fluctuating nutrient availability. Nitrogen (N) is an essential macronutrient that determines growth and productivity. Therefore, plants undergo profound developmental reprogramming when external N levels change. Under N deficiency, most plants reallocate biomass toward the root to enhance nutrient foraging, whereas under sufficient N supply, resources are reallocated to the shoot to promote aboveground growth. In rice, N limitation triggers auxin accumulation in the root by destabilizing the amino transferase DNR1 (DULL NITROGEN RESPONSE 1), thereby promoting root development. In contrast, elevated N increases the abundance of NGR5 (NITROGEN-MEDIATED TILLER GROWTH RESPONSE 5) in the shoot, which activates the expression of multiple shoot-branching genes to enhance tillering. However, the mechanism that coordinates N-responsive reprogramming of root and shoot development remains largely unknown.
RATIONALE
An increase in the root-to-shoot biomass ratio under N limitation is undesirable in agriculture, as excessive root allocation promotes underground competition and reduced shoot growth limits grain yield. Maintaining a stable root-to-shoot ratio under varying N conditions could sustain yield while reducing dependence on environmentally unsustainable fertilizer input. To identify the molecular players coordinating N-responsive developmental reprogramming, we performed a mutant screen and cloned LOC_Os11g03540, corresponding to the seed oil biosynthesis regulator gene OsWRI1a (WRINKLED1a). The oswri1a mutant exhibited similar root-to-shoot biomass ratios without altering carbon reallocation under both high and low N supply. Our subsequent investigation revealed the mechanism by which OsWRI1a coordinates N-responsive development and assessed its potential as a genetic target for crop improvement.
RESULTS
We found that OsWRI1a regulates shoot and root development through both shared and distinct mechanisms. In the shoot, OsWRI1a functions as a transcription factor and directly promotes NGR5 expression, thereby enhancing tillering. In the root, OsWRI1a up-regulates multiple genes involved in N metabolism, leading to improved N-use efficiency (NUE). Root OsWRI1a disrupts the interaction between DNR1 and the F-box protein RNR10 (REGULATOR OF N-RESPONSIVE RSA ON CHROMOSOME 10), which monoubiquitinates DNR1 to inhibit its degradation. RNR10 also mediates the polyubiquitination and degradation of OsWRI1a itself. Elevated OsWRI1a abundance destabilizes DNR1, promoting auxin accumulation and enhancing root development. In contrast, RNR10 does not detectably mediate OsWRI1a degradation in tiller buds, suggesting tissue-specific regulation of OsWRI1a stability. Collectively, OsWRI1a acts as a regulatory hub linking two previously distinct mechanisms that coordinate N-responsive root and shoot development. Finally, we identified a superior OsWRI1a haplotype, predominantly found in indica rice varieties, conferring higher OsWRI1a abundance. Genetically introducing this allele into japonica varieties significantly improved NUE and grain yield.
CONCLUSION
We conclude that N-responsive OsWRI1a integrates root and shoot developmental regulation by transcriptionally activating genes involved in tillering and N metabolism and by disrupting the RNR10-DNR1 negative regulatory module of auxin accumulation specifically in the root. Introgression of a superior natural OsWRI1a haplotype that increases its abundance enables plants to maintain a stable root-to-shoot balance under N limitation and enhances grain yield, highlighting OsWRI1a as a promising target for sustainable crop improvement.
OsWRI1a mediates the coordination of N-responsive root and tiller growth.
OsWRI1a is an N-responsive transcription factor that promotes shoot development by up-regulating the tillering-related gene NGR5 and enhances root development by disrupting the RNR10-DNR1 negative regulatory module controlling auxin accumulation. Elevated OsWRI1a abundance dampens the N deficiency–induced increase in the root-to-shoot biomass ratio, thereby significantly enhancing grain yield while reducing dependence on fertilizer application.
Abstract
Nitrogen (N) deficiency–induced increases in the root-to-shoot biomass ratio in plants are adaptive in nature but suboptimal for agriculture. Understanding the regulatory mechanisms governing this developmental plasticity could help improve crop performance while reducing fertilizer application. We identified OsWRI1a (WRINKLED1a) as a regulatory hub coordinating rice root and shoot growth in response to external N supply, thereby stabilizing the root-to-shoot ratio. In roots, OsWRI1a enhances N-responsive development by promoting auxin accumulation. Meanwhile, shoot OsWRI1a stimulates tiller development and therefore shoot growth. We identified an elite OsWRI1a haplotype that minimizes root-to-shoot ratio fluctuation under N deficiency, improving N-use efficiency and grain yield. Our findings reveal a central mechanism coordinating N-responsive growth allocation for sustainable agriculture.
