In this study, researchers examined nine genetically diverse Lotus japonicus accessions under controlled environment chamber conditions at the National Plant Phenomics Centre (NPPC). Each accession represents a genetically distinct population collected from a particular geographic location so are likely adapted to different climatic conditions..

To test whether the 9 accessions responded differently to flooding, plants were subjected to 10 days of complete submergence, simulating a severe flooding event. Advanced imaging and phenotyping technologies were used to monitor plant growth, photosynthetic performance, flowering time and recovery after the water receded.

This controlled, approach allowed researchers to directly compare how plants with different genetic backgrounds influence flood tolerance and recovery.

1. Flooding significantly reduces plant growth, but recovery is rapid.

Across all varieties studied, flooding caused major declines in biomass (by nearly 37%) and reduced photosynthetic efficiency by over 27%. Yet despite these initial setbacks, each plant recovered its ability to photosynthesise within 10 days of the flood event. This suggests that Lotus japonicus possesses inherent climate resilience that could be harnessed in future crop breeding.

2. Flooding has profound and variable effects on flowering time

One of the most striking and novel findings of the study was the large variation in flowering responses following flooding.

Flooding delayed the onset of flowering by anything from half a day to more than three weeks, depending on the plant’s genetic background and region of origin. Overall, flower production was also reduced by nearly 25%.

Notably, plants originating from different latitudes showed markedly different responses, revealing a strong link between geographic origin and flowering sensitivity to flooding. The scale of this variation, observed across a relatively small number of genetic lines, points to a high level of genetic diversity in how legumes respond to environmental stress.

Because flowering time plays a critical role in determining yield and harvest timing, these findings are particularly important for predicting how future climate conditions may affect crop productivity. They also suggest that specific genes controlling flood tolerance and developmental timing could be identified, opening the door to further genomic research in legumes.

3. Plants use two different survival strategies.

The study also observed two well‑known plant responses to flooding:

• A “sit tight” strategy, where plants stop growing to conserve energy under low-oxygen conditions, termed low-O₂quiescence syndrome (LOQS)
• An “escape” strategy, where plants elongate their shoots upward in an attempt to reach the water’s surface, known as low-O₂escape syndrome (LOES)

Six accessions used the former strategy, while three used the latter. These different responses reflect evolutionary adaptations to local environments and could help guide breeders select traits best suited to specific regions and farming systems.

Supporting Global Food Security

By identifying natural genetic variation in flood tolerance, this research helps inform breeding strategies for more resilient forage and grain legumes. These crops underpin much of the world’s protein supply and livestock feed systems, and more resilient crops mean more stable harvests even under unpredictable weather patterns.

Contributing to Climate-Smart Agriculture

Understanding how plants naturally adapt to stress allows breeders and farmers to reduce reliance on chemical inputs and improve sustainability. Flood-resilient legumes can enhance soil health, store carbon, and integrate into low-emission farming practices.

Guiding Policymakers and Industry Partners

The research provides evidence that can support policies on agricultural resilience and climate adaptation. Supply chains and agri-tech companies can use these insights to develop improved seed varieties and more sustainable farming solutions.

The study highlights the value of Lotus japonicus as a model system for uncovering stress-tolerance mechanisms across the legume family. These insights will help IBERS researchers and commercial partners continue developing the crops of tomorrow, ones that can withstand the challenges of a changing climate while supporting healthier diets, more resilient farms, and a more sustainable planet.

As for Eamon, this final year undergraduate dissertation project was the capstone of his Batchelor degree within the Department of Life Sciences at Aberystwyth University. Gaining a peer-reviewed publication from an undergraduate dissertation is a massive achievement, it surely heralds the start of a successful career in the biological sciences.

The paper Accession-Specific Responses to Submergence Stress in Lotus japonicus: Implications for Legume Climate Resilience is available online here: https://onlinelibrary.wiley.com/doi/10.1111/jac.70166