DOI: 10.5061/dryad.zpc866tgq
title: Drought stress and high heat tolerance in domesticated Phaseolus beans

description: Abiotic constraints, such as drought and heat driven by climate change,
 negatively impact the production of the common bean (Phaseolus vulgaris
 L.), an essential grain legume worldwide. The ability to tolerate drought
 and heat stress in common bean can be improved by introducing genetic
 variation from related species, such as tepary bean (Phaseolus acutifolius
 A. Gray), which has recently gained attention because of its adaptation to
 drought and heat stresses and potential use as a genetic resource and
 alternative crop. To better understand the phenotypic response of tepary
 bean to drought and heat stress in multiple environments and trials and to
 select highly adapted tepary beans, we conducted two field experiments. In
 Experiment 1, we compared the adaptation to drought stress of tepary bean
 (n = 10), common bean (n = 10), and Lima bean (Phaseolus lunatus L.; n =
 9) by assessing the reduction in grain yield under terminal drought
 compared to well-irrigated conditions in two California locations with
 arid summer conditions. Of the three species, tepary bean showed the
 statistically strongest adaptation to terminal drought, followed by Lima
 bean and common bean. In Experiment 2, we evaluated a set of 22 tepary
 beans from contrasting origins for drought and heat stresses across
 multi-environment trials (METs), in California, Nebraska, and Colombia,
 with common bean as a control. We found a considerable variation in the
 tepary bean phenotypic response to these MET conditions, as a result of a
 strong genotype x environment (G x E) interaction. Also, we identified
 tepary bean accessions adapted to drought, heat, and well-irrigated
 conditions across multiple climate zones. Understanding the performance of
 tepary bean across multiple environments and identifying tepary beans with
 broad and target-specific adaptation will maximize the potential use of
 the species.
description: <strong>Experiment 1: Drought evaluation of three
 domesticated Phaseolus species</strong> To
 compare the drought stress response among key domesticated Phaseolus
 species, ten genotypes of each of the common bean and tepary bean and nine
 genotypes of the Lima bean (Supplemental Table S1) were evaluated under
 well-irrigated and terminal drought conditions during the summer of 2016
 in two locations in California (Table 1). These 29 genotypes are
 representative of the genetic diversity in these three species as they
 include representatives of the two domestications in common and Lima beans
 (e.g., Kwak and Gepts, 2009; Garcia et al., 2021) and their breeding
 status (landraces vs. improved varieties). Field trials were conducted at
 the University of California, Agricultural and Natural Resources West Side
 Research and Extension Center (WSREC) (Bsk climate, i.e. arid, cold steppe
 type climate, according to the Köppen-Geiger classification: Peel et al.
 2007; Rubel & Kottek, 2010; Beck et al., 2018), and the University
 of California, Davis, Plant Science Field Facility (UC Davis) (Csa
 climate: temperate with hot, dry summer), which differ in altitude, soil
 type, and average weather data such as precipitation, temperature, and
 relative humidity (Table 1). The plant material was obtained from the seed
 inventory of the Bean Breeding Program, Department of Plant Sciences,
 University of California, Davis. Drought/irrigated
 field trials in both locations were planted side by side in a row-column
 randomized design with three replications. Individual plots consisted of
 two 3 m-rows (50 seeds/row), spaced 0.76 m apart. The drought stress was
 terminal, with irrigation reduced by 50% at WSREC and 75% at UC Davis
 between flowering and harvesting compared with the well-irrigated trial.
 Trials were agronomically maintained using standard common bean commercial
 procedures (Long et al., 2010). To control for spatial variability in each
 trial, best linear unbiased estimators (BLUEs) and best linear unbiased
 predictors (BLUPs) of yield (kg/ha) were fitted using the SPATs package
 (Rodríguez-Álvarez et al., 2018) in the Mr. Bean App (Aparicio et al.,
 2019) (Figures 3 and 4). Genetic correlations of the locations were
 obtained using the statistical program EchidnaMMS (Gilmour, 2020). The
 analysis of variance (ANOVA) was conducted using the lme4 package (Bates
 et al, 2015) in R (R Core Team, 2023). The model, which was fitted with
 the lmer function (Bates et al., 2015), included species, genotype,
 locations, and irrigation/drought treatment as fixed effects.  ANOVA
 calculations utilized the Kenward and Roger (1997) method for determining
 the denominator degrees of freedom to enhance the accuracy of F-tests and
 t-tests for fixed effects.  Mean comparisons were performed with the
 emmeans function using the Tukey test to compare the estimated marginal
 means (Bates et al. 2015). <strong>Experiment 2:
 Evaluation of tepary beans to drought and heat stress throughout
 multi-environment trials (MET)
 study</strong><br><strong>Drought stress
 trials</strong> To determine the drought
 tolerance of tepary beans across different environments, we evaluated 22
 tepary bean genotypes (Table 2) in three drought-stressed and
 well-irrigated trials in three locations in 2017 and 2018. These 22 lines
 were chosen to represent germplasm accessions or landraces (G entries) and
 improved cultivars (TARS-Tep entries) (Table 2) and were selected from a
 wide range of annual mean temperature and annual rainfall (Figure 2). For
 the purpose of comparison, four P. vulgaris breeding lines were also added
 (DOR, SEN, and SEF lines (Table 2). Field trials were conducted in a humid
 tropical environment at the International Center for Tropical Agriculture
 (now called Alliance Bioversity & CIAT), Palmira, Colombia (DrPAL;
 Af climate); a semi-arid temperate environment at the University of
 California, Davis, CA (DrUCD); and a semi-arid temperate climate at the
 University of Nebraska, Panhandle Research and Extension Center,
 Scottsbluff, NE (DrUNL; Bsk climate) (Table 1). Trials were planted during
 the summer seasons in the two temperate locations and during the low
 precipitation season in the tropical location. Environmental conditions
 such as altitude, soil type, and weather data such as precipitation,
 temperature, and relative humidity differed across the three locations
 (Table 1). Drought stress in Palmira was intermittent and moderate, with
 water supply reduced by 28% compared to the well-irrigated trial. Drought
 stress in Davis was terminal and severe, with water supply to the crop
 reduced by ~75% compared to the well-irrigated trial. Drought stress in
 Scottsbluff was terminal and severe, with water supply reduced by 74%
 compared to the well-irrigated trial (Table 1). Drought and well-irrigated
 trials were planted side-by-side in a randomized complete block design
 with three replicates in Palmira, Colombia (PAL), five in Davis, CA (UC
 Davis), and two in Scottsbluff, NE. Individual plots in Davis consisted of
 two rows (50 seeds/row), 3 m-long, and 0.76 m apart; in Palmira, the
 trials were planted in plots 4-row, 3-m-long plots, spaced 0.6 m apart;
 Scottsbluff trials were planted in 2-row, 3.65 m-long plots, 0.6 m apart.
 Trials were agronomically maintained using local, standard common bean
 commercial procedures. High heat trials
 To evaluate the heat tolerance of tepary beans across different
 environments, we evaluated the same 22 drought-tolerance-tested tepary
 bean genotypes (Table 2) under heat stress in three distinct locations in
 2017 and 2018 (Table 1). It has been reported that minimum temperatures
 (i.e., night temperatures) above 20˚C and maximum temperatures (i.e., day
 temperatures) above 30˚C negatively impact the yield production in the
 common bean (Porch & Jahn, 2001; Porch, 2006). Thus, locations
 above the 20/30˚C night/day threshold were selected to conduct the heat
 stress trials. Field trials were planted in two hot and humid tropical
 locations in Alvarado (HtALV; Department of Tolima, Colombia; Af climate)
 and Caribia (HtCAR; Department of Magdalena, Colombia; Af climate), and
 one desert climate at the University of California, Desert Research and
 Extension Center, Holtville, CA (HtDREC; Bwh climate) (Table 1). Reduction
 of water supplied (by rainfall and irrigation, Table 1) provided an
 additional environment in Holtville that combined heat and drought
 stress. High heat trials were planted at low altitudes
 in tropical locations and during the summer season in the desert.
 Environmental conditions such as altitude, soil type, and weather data
 such as precipitation, temperature, and relative humidity differed across
 the three locations (Table 1). Field trials were planted in a randomized
 complete block experimental design, with three replicates in all three
 locations. Plots in Alvarado consisted of two rows (50 seeds/row), 3 m
 long, and 0.6 m apart; in Caribia, the plots consisted of 4 rows (50
 seeds/row), 3 m long, and 0.6 m apart; in Holtville, California, plots
 included 2 rows (50 seeds/row), 3 m long, and 0.76 m apart. Trials were
 agronomically maintained using standard common bean commercial
 procedures.
description: # Drought stress and high heat tolerance in domesticated Phaseolus beans
 [https://doi.org/10.5061/dryad.zpc866tgq](https://doi.org/10.5061/dryad.zpc866tgq) ## Description of the data and file structure ### Files and variables #### File: Experiment\_1\_Legend.docx **Description:** Legend/abbreviations for Experiment_1.xlsx #### File: Experiment\_2\_Legend.docx **Description:** Legend/abbreviations for Experiment_1.xlsx #### File: Experiment\_1.xlsx **Description:** Comparison of drought stress tolerance among and within three domesticated* Phaseolus* (bean) species: common bean (*P. vulgaris*; n = 10), Lima bean (*P. lunatus*; n = 9), and tepary bean (*P. acutifolius*; n = 10). These were planted in 2016 in two locations with contrasting climate in the Central Valley of California: UC Davis and the West Side Research & Extension Center of UC ANR. ##### Variables * Input variables: Species (3), locations (2), treatments (2), and genotypes (9 or 10; 29); Output variables: DF: days to flowering; YDHA: yield per area (kg/ha) * ``` Missing values: N/A ``` #### File: Experiment\_2.xlsx **Description:** Comparison  of drought stress or high heat tolerance in tepary bean (*P. acutifolius*; n = 22) with common bean (*P. vulgaris*; n =5), planted in four locations (California, Nebraska, and Colombia) for drought stress and two locations for high heat (California, Colombia). ##### Variables * Input variablesL Species (2), locations (drought: 4; heat: 3), genotypes (22); output variables: YDHA (yield per hectare, kg/ha), DF (days to flowering), DPM (days to physiological maturity), 100SW (hundred-seed weight, g). Missing values: NA ## Code/software Microsoft Excel can be used to view these files.