Response to oxalic acid: an important supplement screening against stem rot resistance in groundnut (Arachis hypogaea L.)

Abstract

Background Stem rot, caused by the soil-borne pathogen Sclerotium rolfsii, pose a serious challenge in the groundnut (Arachis hypogaea L) cultivation. Although this disease is widespread globally but had most adverse impact in groundnut growing regions of United States, India, and Australia. The pathogen primarily targets the crown region of the plant, resulting in systemic collapse and potentially leading to yield losses up to 80%. Effective genetic control measures are essential to mitigate the impact of this disease on groundnut production. Realizing the time and resource-consuming complex field-based phenotyping, the availability of easy and repeatable phenotyping methods may fasten the process of donor and gene discovery efforts. Results Multi-season phenotyping was performed for stem rot on 184 minicore germplasm accessions, including checks, under two conditions: sick field screening and response to oxalic acid assay. This study demonstrated medium to high heritability (52-63% broad-sense heritability) and significant environmental influence (36%). The response to the oxalic acid assay showed a high proportion of similarity (approximately 80%) with the percent mortality observed in the sick field indicating an easy way of performing precise phenotyping. Notably, seven genotypes-ICG163, ICG721, ICG10479, ICG875, ICG11457, ICG111, and ICG2857-exhibited stable resistance, with less than 30% mortality against stem rot disease. Among these, ICG163, ICG875, and ICG111 displayed low mortality and consistent stability across multiple seasons in both the sick field and controlled conditions of the oxalic acid assay. Conclusions The oxalic acid assay developed in this study effectively complements field phenotyping, as a reliable method for assessing stem rot resistance. Seven resistant genotypes identified through this assay can be utilized for the introgression of stem rot resistance into elite genotypes. Given the significant influence of the environment on stem rot resistance, it is essential to implement multi-season phenotyping to obtain precise results. Furthermore, the response to oxalic acid serves as a valuable supplement to traditional field phenotyping, since maintaining uniform disease pressure during field screenings is often challenging.

Plant phenotyping relevance

落花生の茎腐病抵抗性を評価するシュウ酸アッセイを開発し、圃場表現型との一致性・遺伝率・再現性を検証した研究であり、植物病害表現型の取得法が中心である。

Code and data availability

The paper reports multi-season sick-field and oxalic acid assay phenotyping of 184 groundnut minicore accessions, with supplementary materials (including an XLSX likely containing phenotype data) linked only through the article page. No authors' public repository, code deposit, dataset deposit, or actionable paper URL/

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