Genetic association of stomatal traits and yield in wheat grown in low rainfall environments

Fahimeh Shahinnia (1, 2) , Julien Le Roy (3, 4, 5, 1) , Benjamin Laborde (6, 1) , Beata Sznajder (1) , Priyanka Kalambettu (1) , Saba Mahjourimajd (1) , Joanne Tilbrook (1) , Delphine Fleury (1)

1 Australian Centre for Plant Functional Genomics and School of Agriculture, Food and Wine, Waite Research Institute
2 Leibniz Institute of Plant Genetics and Crop Plant Research
3 UGSF - Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576
4 CNRS - Centre National de la Recherche Scientifique
5 Université de Lille
6 Montpellier SupAgro - Institut national d’études supérieures agronomiques de Montpellier

Background: In wheat, grain filling is closely related to flag leaf characteristics and function. Stomata are specialized leaf epidermal cells which regulate photosynthetic CO2 uptake and water loss by transpiration. Understanding the mechanisms controlling stomatal size, and their opening under drought, is critical to reduce plant water loss and maintain a high photosynthetic rate which ultimately leads to elevated yield. We applied a leaf imprinting method for rapid and non-destructive phenotyping to explore genetic variation and identify quantitative traits loci (QTL) for stomatal traits in wheat grown under greenhouse and field conditions. Results: The genetics of stomatal traits on the adaxial surface of the flag leaf was investigated using 146 double haploid lines derived from a cross between two Australian lines of Triticum aestivum, RAC875 and Kukri. The drought tolerant line RAC875 showed numerous small stomata in contrast to Kukri. Significant differences between the lines were observed for stomatal densitity and size related traits. A negative correlation was found between stomatal size and density, reflecting a compensatory relationship between these traits to maintain total pore area per unit leaf surface area. QTL were identified for stomatal traits on chromosomes 1A, 1B, 2B, and 7A under field and controlled conditions. Most importantly some of these loci overlap with QTL on chromosome 7A that control kernel number per spike, normalized difference vegetation index, harvest index and yield in the same population. Conclusions: In this first study to decifer genetic relationships between wheat stomatal traits and yield in response to water deficit, no significant correlations were observed among yield and stomatal traits under field conditions. However we found some overlaps between QTL for stomatal traits and yield across environments. This suggested that stomatal traits could be an underlying mechanism increasing yield at specific loci and used as a proxy to track a target QTL in recombinant lines. This finding is a step-forward in understanding the function of these loci and identifying candidate genes to accelerate positional cloning of yield QTL in wheat under drought.

Mots clés: Drought; Epidermal cells; Flag leaf; QTL; Stomatal density; Stomatal size; Triticum aestivum

Domaines: Sciences du Vivant [q-bio]

Fahimeh Shahinnia, Julien Le Roy, Benjamin Laborde, Beata Sznajder, Priyanka Kalambettu, et al.. Genetic association of stomatal traits and yield in wheat grown in low rainfall environments. BMC Plant Biology, 2016, 16, pp.1-14. ⟨10.1186/s12870-016-0838-9⟩. ⟨hal-01605482⟩