Optimization of Greenhouse Waterlogging Tolerance Screening and Low-Cost Seminal Roots Phenotyping Methods for Spring Wheat

Abstract Climate change projections predict that precipitation in Norway is likely to increase, and flooding and waterlogging scenarios will likely be more frequent in the future. Wheat is sensitive to waterlogging conditions, and there can be substantial yield loss due to waterlogging stress in wheat. However, there is a genetic variation in waterlogging tolerance in wheat. Screening for waterlogging tolerance in wheat has been done for many years, but the screening methodology varies with climate, soil, crop stage, and waterlogging event itself. Field screening for waterlogging tolerance in wheat is labor-intensive, time-consuming, and high cost. Here, we developed and improved a methodology to screen waterlogging tolerance in wheat in the greenhouse, which can simulate field water logging conditions. Our greenhouse waterlogging methodology using starch (0.1% m/v) is promising and creates a highly reduced environment (below -500 mV) within four days of waterlogging. Using chlorosis as a trait for evaluating waterlogging tolerance, Best Linear Unbiased Predictors (BLUPs) of twenty spring wheat genotypes tested with this methodology showed a correlation of (R=0.44) with previously obtained field data for the same trait. The developed greenhouse waterlogging method using starch (0.1 % m/v) is cost-effective, time-efficient, and labor efficient compared to field screenings. Utilizing this method, screening for waterlogging tolerance in wheat can be done within one month of waterlogging. Chlorosis percentage and recovery scale are two phenotypic traits used for screening wheat genotypes in this method. This method is promising for efficiently screening diverse wheat populations for waterlogging tolerance within greenhouse settings, with potential application in other crops. Notably, twenty spring wheat genotypes used to optimize this methodology were also collections of genotypes with contrasting haplotypes on QTL6A.2 for chlorosis. These haplotypes have significant differences (P < 0.05) for chlorosis on field waterlogging and under this greenhouse waterlogging methodology. Follow-up experiments using this methodology would be recommended in further studies on validating this QTL. Additionally, we established a cost-effective root phenotyping methodology using seed germination pouches with germination paper (dark blue grade 194) for phenotyping seminal root angle of wheat genotypes. Utilizing this method, contrasting haplotypes on QTL6A.2 for chlorosis were tested for seminal root angle, and these haplotypes were found to have significant differences in seminal root angle. This result needs verification through further experiments. Identification of candidate genes on this locus would be recommended to understand the role of seminal root angle on waterlogging tolerance. This work establishes a greenhouse-based waterlogging screening method as alternative or supplement to field screening. It shows promise for large-scale screening and QTL identification/validation for waterlogging tolerance of wheat population. Additionally, seminal root phenotyping method developed for assessing traits like seminal root angle, has potential applications in waterlogging tolerance screening as seminal root angle is proxy trait

Abstract Climate change projections predict that precipitation in Norway is likely to increase, and flooding and waterlogging scenarios will likely be more frequent in the future. Wheat is sensitive to waterlogging conditions, and there can be substantial yield loss due to waterlogging stress in wheat. However, there is a genetic variation in waterlogging tolerance in wheat. Screening for waterlogging tolerance in wheat has been done for many years, but the screening methodology varies with climate, soil, crop stage, and waterlogging event itself. Field screening for waterlogging tolerance in wheat is labor-intensive, time-consuming, and high cost. Here, we developed and improved a methodology to screen waterlogging tolerance in wheat in the greenhouse, which can simulate field water logging conditions. Our greenhouse waterlogging methodology using starch (0.1% m/v) is promising and creates a highly reduced environment (below -500 mV) within four days of waterlogging. Using chlorosis as a trait for evaluating waterlogging tolerance, Best Linear Unbiased Predictors (BLUPs) of twenty spring wheat genotypes tested with this methodology showed a correlation of (R=0.44) with previously obtained field data for the same trait. The developed greenhouse waterlogging method using starch (0.1 % m/v) is cost-effective, time-efficient, and labor efficient compared to field screenings. Utilizing this method, screening for waterlogging tolerance in wheat can be done within one month of waterlogging. Chlorosis percentage and recovery scale are two phenotypic traits used for screening wheat genotypes in this method. This method is promising for efficiently screening diverse wheat populations for waterlogging tolerance within greenhouse settings, with potential application in other crops. Notably, twenty spring wheat genotypes used to optimize this methodology were also collections of genotypes with contrasting haplotypes on QTL6A.2 for chlorosis. These haplotypes have significant differences (P < 0.05) for chlorosis on field waterlogging and under this greenhouse waterlogging methodology. Follow-up experiments using this methodology would be recommended in further studies on validating this QTL. Additionally, we established a cost-effective root phenotyping methodology using seed germination pouches with germination paper (dark blue grade 194) for phenotyping seminal root angle of wheat genotypes. Utilizing this method, contrasting haplotypes on QTL6A.2 for chlorosis were tested for seminal root angle, and these haplotypes were found to have significant differences in seminal root angle. This result needs verification through further experiments. Identification of candidate genes on this locus would be recommended to understand the role of seminal root angle on waterlogging tolerance. This work establishes a greenhouse-based waterlogging screening method as alternative or supplement to field screening. It shows promise for large-scale screening and QTL identification/validation for waterlogging tolerance of wheat population. Additionally, seminal root phenotyping method developed for assessing traits like seminal root angle, has potential applications in waterlogging tolerance screening as seminal root angle is proxy trait