Genetic variation of wheat seedling root angle

Phenotyping wheat seedling’s root angle variation to highlight correlations with water stress Clothilde Collet, Xavier Draye. An increasing diversity of water limited scenarios is predicted by climate research. Because roots determine soil-root conductance and water extraction[1], root traits have been proposed as a priority target to breed for drought tolerant yielding crops. There are many reports that the seminal root angle of cereal seedlings is a good predictor of several aspects of field root architecture[2], including deep root distribution[3],[4], which is considered as a positive adaptation to drought scenarios[5]. We have carried out an experiment under controlled conditions to analyse the genetic determinism of seminal root angles of wheat seedlings. Two diversity panels have been studied: a bread wheat diversity panel (250 varieties) and a durum wheat diversity panel (250 varieties). Seedlings (12 per genotype) were disposed at six different heights on a vertical germination paper plate whose moisture was maintained by capillary rise of water from the bottom of the plate. Daily pictures of the root systems have been captured during a 4-day long experiment and have been vectorized with the SmartRoot program. We observed a weak but significant correlation between the metric potential of water in the filter paper and the seedling seminal root angle. We also confirm that there is a very high broad-sense heritability for the root angle within each panel. This experiment is part of the EU project SolACE (http://www.solace-eu.net). [1] Xavier Draye et al., ‘Model-Assisted Integration of Physiological and Environmental Constraints Affecting the Dynamic and Spatial Patterns of Root Water Uptake from Soils’, Journal of Experimental Botany 61, no. 8 (May 2010): 2145–55, https://doi.org/10.1093/jxb/erq077. [2] Ahmad M. Manschadi et al., ‘The Role of Root Architectural Traits in Adaptation of Wheat to Water-Limited Environments’, Functional Plant Biology 33, no. 9 (22 September 2006): 823–37, https://doi.org/10.1071/FP06055; Manschadi et al. [3] A. Oyanagi, ‘Gravitropic Response Growth Angle and Vertical Distribution of Roots of Wheat (Triticum Aestivum L.)’, Plant and Soil165, no. 2 (1994): 323–26. [4] A. M. Manschadi et al., ‘Experimental and Modelling Studies of Drought‐adaptive Root Architectural Traits in Wheat (Triticum Aestivum L.)’, Plant Biosystems - An International Journal Dealing with All Aspects of Plant Biology 144, no. 2 (1 June 2010): 458–62, https://doi.org/10.1080/11263501003731805. [5] Ahmad M. Manschadi et al., ‘Genotypic Variation in Seedling Root Architectural Traits and Implications for Drought Adaptation in Wheat (Triticum Aestivum L.)’, Plant and Soil 303, no. 1 (1 February 2008): 115–29, https://doi.org/10.1007/s11104-007-9492-1