Divergence of root system plasticity in soybean between modern breeding lines and diverse germplasm accessions

Authors: BOGATI, SUSJATA - Purdue University; CARPENTER, JOSHUA - Purdue University; JUNG, JINHA - Purdue University; SCHAFER, SAM - Purdue University; DANAO, JAIRAM - Purdue University; WOODS, ELLEN - Wesleyan University; Song, Qijian; KANTAR, MICHAEL - University Of Hawaii; MA, JIANXIN - Purdue University; WANG, DIANA - Purdue University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2025
Publication Date: 11/24/2025
Citation: Bogati, S., Carpenter, J., Jung, J., Schafer, S., Danao, J., Woods, E., Song, Q., Kantar, M., Ma, J., Wang, D. 2025. Divergence of root system plasticity in soybean between modern breeding lines and diverse germplasm accessions. Crop Science. 65(6). Article e70190. https://doi.org/10.1002/csc2.70190.
DOI: https://doi.org/10.1002/csc2.70190

Interpretive Summary: Root systems play a key role in anchoring plants, absorbing nutrients, and supporting beneficial interactions with soil microbes. However, modern breeding has mostly focused on above-ground traits, leaving the effects on root system architecture (RSA) in cultivated soybeans largely unexplored. This study compared RSA in elite breeding lines and diverse landraces (varieties) across different environments and growth stages. Using 2D imaging and a new low-cost 3D modeling method, researchers analyzed 432 root systems. They found that elite lines generally had larger root systems but showed less plasticity—reduced ability to adapt to soil differences—which may limit their resilience. In contrast, landraces showed greater plasticity, making them valuable genetic resources for improving adaptability. These results challenge earlier claims that elite lines tend to have smaller, more efficient root systems. Instead, RSA appears to have expanded, likely due to selection for higher yields. The study underscores the importance of including RSA in breeding programs and highlights the potential of affordable 3D root phenotyping tools.

Technical Abstract: Roots are critical to supporting basic plant functions such as anchoring in various substrates, uptake of water and nutrients, and hosting symbiotic relationships. In crop species, indirect changes to root system architecture (RSA) have occurred largely as a result of selection for yield or other related aboveground traits. In cultivated soybean (Glycine max), evidence of changes to RSA as a result of breeding for crop performance has been inconsistent, with some studies supporting an overall decrease in trait values, such as root length and density, and other work showing the opposite. The current study sets out to ask whether there is any systematic differentiation in RSA between a set of elite breeding lines (n=8) of soybean developed for the Midwest United States and a group of biogeographically diverse landraces from the USDA Soybean Germplasm Collection (n=16) across three distinct developmental stages (V2–V6, V7–R2, R3–R7) and two contrasting soil environments. In total, 432 root systems are phenotyped for 12 structural traits derived from 2D images along with root and shoot biomass. A new 3D root modeling approach leveraging photogrammetry-derived pointclouds is additionally tested on a subset of 38 contrasting root systems. Results indicate that the diversity lines had smaller root systems overall but greater plasticity in response to soil environment as compared to breeding lines. Additionally, the study finds evidence for trade-offs between above-ground and below-ground trait phenotypic plasticity.