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ABSTRACT Plant roots are the critical interface between plants, soil, and microorganisms, and respond dynamically to changes in water availability. Although anatomical adaptations of roots to water stress (e.g., the formation of root cortical aerenchyma) are well documented, it remains unclear whether these responses manifest along the length of individual roots under both water deficiency and water overabundance. We investigated the anatomical responses ofTripsacum dactyloidesL. to both drought and waterlogging stress at high spatial resolution. Nodal roots were segmented into one‐centimeter sections from the tip to the base, allowing us to pinpoint regions of maximal anatomical change. Both stressors overall increased the proportion of root cortical aerenchyma, but metaxylem responses differed: waterlogging increased the proportion of the stele that was occupied by metaxylem with fewer but larger vessels. Drought significantly increased root hair formation within two centimeters of the root tip. The most pronounced anatomical changes occurred 3–7 cm from the root tip, where cortical cell density declined as aerenchyma expanded. These findings highlight spatial variation in root anatomical responses to water stress and provide a framework that can inform sampling protocols for various other data types where sampling effort is limiting (e.g., microbiome, transcriptome, proteome). 

Premise: Plant roots are the critical interface between plants, soil, and microorganisms, and respond dynamically to changes in water availability. Although anatomical adaptations of roots to water stress (e.g., the formation of root cortical aerenchyma) are well documented, it remains unclear whether these responses manifest along the length of individual roots under both water deficiency and water over-abundance. Methods: We investigated the anatomical responses of Tripsacum dactyloides L. to both drought and flood stress at high spatial resolution. Nodal roots were segmented into one-centimeter sections from the tip to the base, allowing us to pinpoint regions of maximal anatomical change. Results: Both stressors increased the proportion of root cortical aerenchyma, but metaxylem responses differed: flooding increased vessel area whereas drought led to smaller vessels, with both showing a lower number of vessels. Drought also significantly increased root hair formation, but only within the first two centimeters. The most pronounced anatomical changes occurred 3-7 cm from the root tip, where cortical cell density declined as aerenchyma expanded. Discussion: These findings highlight spatial variation in root anatomical responses to water stress and provide a framework integrating various other data types where sampling effort is limiting (e.g., microbiome, transcriptome, proteome). 

Societal Impact StatementThe innumerable effects of terroir—including climate, soil, microbial environment, biotic interactions, and cultivation practice—collectively alter plant performance and production. A more direct agricultural intervention is grafting, in which genetically distinct shoot and root genotypes are surgically combined to create a chimera that alters shoot performance at a distance. Selection of location and rootstock are intentional decisions in viticulture to positively alter production outcomes. Here, we show that terroir and rootstock alter the shapes of grapevine leaves in commercial vineyards throughout the California Central Valley, documenting the profound effects of these agricultural interventions that alter plant morphology. SummaryEmbedded in a single leaf shape are the latent signatures of genetic, developmental, and environmental effects. In viticulture, choice of location and rootstock are important decisions that affect the performance and production of the shoot. We hypothesize that these effects influence plant morphology, as reflected in leaf shape.We sample 1879 leaves arising from scion and rootstock combinations from commercial vineyards in the Central Valley of California. Our design tests 20 pairwise contrasts between Cabernet Sauvignon and Chardonnay scions from San Joaquin, Merced, and Madera counties from vines grafted to Teleki 5C, 1103 Paulsen, and Freedom rootstocks.We quantify clear differences between Cabernet Sauvignon and Chardonnay leaves. However, we also detect a separate, statistically independent source of shape variance that affects both Cabernet Sauvignon and Chardonnay leaves similarly. We find that this other shape difference is associated with differences in rootstock and location.The shape difference that arises from rootstock and location affects the basal part of the leaf near the petiole, known as the petiolar sinus, and affects its closure. This shape effect is independent from previously described shape differences that arise from genetic, developmental, or size effects. 

Grapevine leaves have diverse shapes and sizes which are influenced by many factors including genetics, vine phytosanitary status, environment, leaf and vine age, and node position on the shoot. To determine the relationship between grapevine leaf shape or size and leaf canopy temperature, we examined five seedling populations grown in a vineyard in California, USA. The populations had one parent with compound leaves of the Vitis piasezkii type and a different second parent with non-compound leaves. In previous work, we had measured the shape and size of the leaves collected from these populations using 21 homologous landmarks. Here, we paired these morphological data with canopy temperature measurements made using a handheld infrared thermometer. After recording time of sampling and canopy temperature, we used a linear model between time of sampling and canopy temperature to estimate temperature residuals. Based on these residuals, we determined if the canopy temperature of each vine was cooler or warmer than expected, based on the time of sampling. We established a relationship between leaf size and canopy temperature: vines with larger leaves were cooler than expected. By contrast, leaf shape was not strongly correlated with variation in canopy temperature. Ultimately, these findings indicate that vines with larger leaves may contribute to the reduction of overall canopy temperature; however, further work is needed to determine whether this is due to variation in leaf size, differences in the openness of the canopy or other related traits.