Nitrogen Resilience in Waterlogged Soybean plants

Aditi Manjare, Institute of Bioinformatics and Biotechnology, SPPU, Pune

Introduction

Increasing extreme weather events, such as heavy rain and waterlogging, have impacted legumes, disrupting their nitrogen uptake and crop yield. In this environment, microorganisms associated with roots play a crucial role in controlling the uptake of nitrogen. Waterlogging disrupts the balance, decreases oxygen levels, hinders the symbiotic N2 fixation process, and impedes the nitrification process. This leads to shifts in microbial communities and reduced productivity, as nutrient-rich soil washes away.

The paper this article talks about delves deep into the interplay between soybean genotypes and waterlogging’s effects on nitrogen cycling. These responses were influenced by soil characteristics such as texture, porosity, and pH. Underlying this was the collaboration between resilient genotypes and specific microorganisms that mitigate stresses.

The study also examined how soybean genotypes responded to waterlogging, evaluating nitrogen acquisition and the rhizosphere’s microbial landscape. Recognizing these intricate relationships is considered vital for sustainable agriculture in a world confronting changing climates.

Decoding the dynamics of soil waterlogging

For this study, the researchers chose two soybean cultivation regions in China: Suixi County (with Udic Argosol soil type) and Yingde County (with Haplic Alisol soil type). The investigation focuses on two soybean genotypes, the resilient Qihuang34, and the sensitive Jidou17. Greenhouse experiments involved randomized blocks with nine replicates for each treatment, assessing soil type, genotype, and waterlogging stress.

The study measured plant nitrogen (N) derived from atmospheric N₂, N fertilizer, and soil mineralization using the ¹⁵N dilution method. Nitrifiers and denitrifiers abundance were quantified by quantitative PCR (qPCR) of bacterial and archaeal marker genes, while bioinformatics and statistical tools were used to process and assess various characteristics of the amplicon sequence variants (ASVs). Factors such as ribosomal features were considered for filtration of the generated data and then classified taxonomically. Some of the other parameters assessed included the soil type, waterlogging stress, beta-diversity of varying soybean variants, etc. The researchers conducted tests, such as factorial ANOVA, Tukey’s HSD, Pielou’s evenness, and Shannon diversity for Alpha-diversity, and Bray–Curtis dissimilarity for beta-diversity, to establish statistical significance.

The research paper elaborates the response of various soybean genotypes to waterlogging. The study highlights the impact of waterlogging on nitrogen uptake, seed yield, and microbial communities, which vary depending on the soil type. The resilient genotype, for instance, shows superior nitrogen uptake and forms unique microbial communities closely connected to the nitrogen cycle in the rhizosphere.

The researchers found that waterlogging negatively affects the nitrogen uptake in soybeans, leading to a reduction in yield. This is due to a decrease in nitrogen acquisition from both symbiotic nitrogen fixation and fertilizer.

The lack of oxygen in the soil during waterlogging also affected root respiration and nodulation, which disrupted the uptake of nitrogen as well. Soil properties, such as porosity and clay content, determine the extent of these effects, with the Udic Argosol experiencing more severe impacts.

Conclusion

These remarkable findings regarding the rhizosphere of the resilient genotype, with its increased ammonia oxidizers and reduced denitrifiers, hold significant implications. This suggested the potential for elevated plant-accessible nitrate levels, ultimately enhancing plant nutrition.

The study also highlighted rhizosphere microorganisms’ crucial role in reducing plant stress, especially in waterlogged conditions. Alterations in microbial communities can have varying effects on nitrogen absorption in different genotypes and soils.

It emphasizes the complex relationship between plant response, soil characteristics, and microorganisms, providing insights on how to improve nitrogen efficiency in waterlogged conditions. These findings are an important piece of the puzzle in developing waterlogging resilience and call for further research to assess their broader implications.

Also read: Cell Senescence in Type II Diabetes: Therapeutic Potential

Reference:

Lian, T., Cheng, L., Liu, Q. et al. Potential relevance between soybean nitrogen uptake and rhizosphere prokaryotic communities under waterlogging stress. ISME COMMUN. 3, 71 (2023). https://doi.org/10.1038/s43705-023-00282-0

The Corrosion Prediction from the Corrosion Product Performance