ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
This article is part of the Research TopicInvestigating the Elements of Plant Defense Mechanisms Within Plant Immune Responses Against Pathogens, Volume IIView all 15 articles
Balancing Growth and Defense: miRNA-Mediated Regulation of Phosphorus Allocation and Antiviral Immunity in Soybean Under Normal Light and Shade
Provisionally accepted
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
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Balancing growth and defense under fluctuating environments is critical for plant resilience. This study uncovers how microRNA-mediated phosphorus (P) allocation regulates this equilibrium in soybean under variable light. We demonstrate that miR397a acts as a susceptibility factor by repressing laccase genes GmLAC7 and GmLAC12, compromising lignin-based structural defense and enhancing Soybean mosaic virus (SMV) accumulation under normal light. Conversely, miR399j enhances resistance through targeted suppression of the phosphate transporter GmPHT1-4, reprogramming systemic P distribution to favor leaf allocation and support defense capacity. Under shade, however, the relationship between light, P, and immunity becomes context-dependent: although early SMV accumulation is reduced—likely reflecting slowed viral replication or growth prioritization—shade simultaneously induces systemic P reallocation to roots, depleting shoot P pools. This creates a metabolic bottleneck that uncouples GmLAC7/12 up-regulation from functional lignin deposition in miR397a-silenced plants, ultimately impairing structural barriers and permitting viral spread during sustained infection. Critically, exogenous P application restores lignin synthesis and suppresses SMV under shade, confirming P availability as the limiting factor. Our findings establish a light-gated hierarchy of resource allocation: under optimal light, miR399j directs P toward aerial defense; under shade, P conservation in roots comes at the cost of inducible structural immunity. This mechanistic framework offers new strategies for optimizing crop resilience in heterogeneous light environments.
Keywords: Defense, miRNA, Phosphorus absorption, shade (low light intensity), Soybean mosaic virus
Received: 17 Sep 2025; Accepted: 22 Dec 2025.
Copyright: © 2025 Shang, Yang, Li, Hu, Du and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jing Shang
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