High-throughput phenotyping of soybean transpiration response curves to rising atmospheric drying in a mapping population

Abstract

Abstract In soybean, limiting whole-plant transpiration rate (TR) response to increasing vapor pressure deficit (VPD) has been associated with the ‘slow-wilting’ phenotype and with water- conservation enabling higher yields under terminal drought. Despite the promise of this trait, it is still unknown whether it has a genetic basis in soybean, a challenge limiting the prospects of breeding climate-resilient varieties. Here we present the results of a first attempt at a high- throughput phenotyping of TR and stomatal conductance response curves to increasing VPD conducted on a soybean mapping population consisting of 140 recombinant inbred lines (RIL). This effort was conducted over two consecutive years, using a controlled-environment, gravimetric phenotyping platform which enabled characterizing 900 plants for these responses, yielding regression parameters (R 2 from 0.92 to 0.99) that were used for genetic mapping. Several quantitative trait loci (QTL) were identified for these parameters on chromosomes (Ch) 4, 6 and 10, including a VPD-conditional QTL on Ch 4 and a ‘constitutive’ QTL controlling all parameters on Ch 6. This study demonstrated for the first time that canopy water use in response to rising VPD has a genetic basis in soybean, opening novel avenues for identifying alleles enabling water conservation under current and future climate scenarios.

Plant phenotyping relevance

制御環境の重量計測フェノタイピング基盤を用いて、900個体の蒸散・気孔コンダクタンス応答曲線を高スループット取得し、再利用可能な生理形質抽出を実施しているため、方法の適用が研究の主要部分です。

Code and data availability

The paper's phenotyping data (TR/VPD response curves for 900 plants, regression parameters, QTL mapping results) are not publicly deposited; the authors state data will be shared only upon reasonable request. No author analysis code, scripts, or public repository URL is provided; R packages cited (qtl, qtl2, lmerTest)

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