A high-throughput approach for quantifying turgor loss point in wine grapes

Abstract

Abstract Quantifying drought tolerance in crops is critical for agricultural management under environmental change, and drought response traits in wine grapes have long been the focus of viticultural research. Turgor loss point ( π tlp ) is gaining attention as an indicator of drought tolerance in plants, though estimating π tlp often requires the construction and analysis of pressure-volume (P-V) curves which is time consuming. While P-V curves remain a valuable tool for assessing π tlp and related traits, there is considerable interest in developing high-throughput methods for rapidly estimating π tlp , especially in the context of crop screening. We tested the ability of a dewpoint hygrometer to quantify variation in π tlp across and within 12 varieties of wine grapes ( Vitis vinifera ) and one wild relative ( Vitis riparia ) and compared these results to those derived from P-V curves. At the leaf-level, methodology explained only 4–5% of the variation in π tlp while variety/species identity accounted for 39% of the variation, indicating that both methods are sensitive to detecting intraspecific π tlp variation in wine grapes. Also at the leaf level, π tlp measured using a dewpoint hygrometer significantly approximated π tlp values ( r 2 = 0.254) and conserved π tlp rankings from P-V curves (Spearman’s ρ = 0.459). While the leaf-level datasets differed statistically from one another (paired t -test p = 0.01), average difference in π tlp for a given pair of leaves was small (0.1 ± 0.2 MPa (s.d.)). At the species/variety level, estimates of π tlp measured by the two methods were also statistically correlated ( r 2 = 0.304), did not deviate statistically from a 1:1 relationship, and conserved π tlp rankings across varieties (Spearman’s ρ = 0.692). The dewpoint hygrometer (taking ~ 10–15 minutes on average per measurement) captures fine-scale intraspecific variation in π tlp , with results that approximate those from P-V curves (taking 2–3 hours on average per measurement). The dewpoint hygrometer represents a viable method for rapidly estimating intraspecific variation in π tlp , and potentially greatly increasing replication when estimating this drought tolerance trait in wine grapes and other crops.

Plant phenotyping relevance

ブドウ葉の乾燥耐性形質（膨圧損失点）を高スループットに推定する露点湿度計法を開発・圧力容積曲線法と比較検証しており、フェノタイピング手法が中心である。

Code and data availability

The supplied blocks contain no data availability, code availability, or supplementary material statements. The paper describes turgor loss point measurements (P-V curves and dewpoint hygrometer) on wine grapes, but no public phenotype dataset, author code repository, or trained model is mentioned. The only software all

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