Phenotyping and Quantitative Trait Locus Analysis for the Limited Transpiration Trait in an Upper-Mid South Soybean Recombinant Inbred Line Population (“Jackson” × “KS4895”): High Throughput Aquaporin Inhibitor Screening

Abstract

Soybean is most often grown under rainfed conditions and negatively impacted by drought stress in the upper mid-south of the United States. Therefore, identification of drought-tolerance traits and their corresponding genetic components are required to minimize drought impacts on productivity. Limited transpiration (TRlim) under high vapor pressure deficit (VPD) is one trait that can help conserve soybean water-use during late-season drought. The main research objective was to evaluate a recombinant inbred line (RIL) population, from crossing two mid-south soybean lines (“Jackson” × “KS4895”), using a high-throughput technique with an aquaporin inhibitor, AgNO3, for the TRlim trait. A secondary objective was to undertake a genetic marker/quantitative trait locus (QTL) genetic analysis using the AgNO3 phenotyping results. A set of 122 soybean genotypes (120-RILs and parents) were grown in controlled environments (32/25-d/n °C). The transpiration rate (TR) responses of derooted soybean shoots before and after application of AgNO3 were measured under 37°C and >3.0 kPa VPD. Then, the decrease in transpiration rate (DTR) for each genotype was determined. Based on DTR rate, a diverse group (slow, moderate, and high wilting) of 26 RILs were selected and tested for the whole plant TRs under varying levels of VPD (0.0–4.0 kPa) at 32 and 37°C. The phenotyping results showed that 88% of slow, 50% of moderate, and 11% of high wilting genotypes expressed the TRlim trait at 32°C and 43, 10, and 0% at 37°C, respectively. Genetic mapping with the phenotypic data we collected revealed three QTL across two chromosomes, two associated with TRlim traits and one associated with leaf temperature. Analysis of Gene Ontologies of genes within QTL regions identified several intriguing candidate genes, including one gene that when overexpressed had previously been shown to confer enhanced tolerance to abiotic stress. Collectively these results will inform and guide ongoing efforts to understand how to deploy genetic tolerance for drought stress.

Cotton stomatal closure under varying temperature and vapor pressure deficit, correlation with the hydraulic conductance trait

“…Under high temperatures, cultivars without the ability to restrict hydraulic conductance would allow water to readily replenish leaves, resulting in open stomata and unrestricted transpiration with the increasing VPD (Pradhan et al 2019;Li et al 2020;Sadok and Sinclair 2010;Sarkar et al 2022). In soybean, observations of the TR lim trait and low leaf hydraulic conductance (K leaf ) [i.e., decrease in transpiration rate (TR)] at 32 °C do not necessarily predict expression of the trait at higher temperatures (Sarkar et al 2022). By increasing temperature from 32 to 37 °C, the expression of TR lim trait was reduced to ~ 43%, 10%, and 0% for slow, moderate, and high wilting soybean genotypes, respectively.…”

Identification of candidate genes controlling red seed coat color in cowpea (Vigna unguiculata[L.] Walp)

“…Similarly, the closest homolog in soybean is Glyma.10G018800 , with 90.26% identity and an e-value of 0.0 from pairwise BLAST of the coding sequence. Interestingly, Glyma.10G018800 shows elevated expression in the root (https://phytozome-next.jgi.doe.gov/report/transcript/Gmax_Wm82_a4_v1/Glyma.10G018800.1) and has been identified as a candidate gene controlling root growth [41], [42], potentially resulting from divergent evolution.…”

Identifying physiological and genetic determinants of faba bean transpiration response to evaporative demand

“…In wheat ( Triticum aestivum ), six QTLs associated with the transpiration response to VPD were identified, of which one major QTL included genes involved in root hydraulic conductance and ABA signalling ( Schoppach et al ., 2016 ). Similarly, in soybean, limited transpiration was associated with two QTLs that harbour several candidate genes, including one involved in abiotic stress tolerance ( Sarkar et al ., 2022 ). In chickpea, transpiration efficiency (ratio of biomass per unit of transpired water) was associated with the ‘ QTL-hotspo t’ region that harboured four genes associated with drought adaptation ( Barmukh et al ., 2022 ).…”