Assesing the genetic variability of sensitivity to water deficit in phenotyping platform for 100s maize genotypes

SANTIAGO ALVAREZ PRADO; LLORENÇ CABRERA-BOSQUET; ANTONIN GRAU; CLAUDE WELCKER; FRANÇOIS TARDIEU

Jacksonville

Congreso; 58th Annual Maize Genetics Conference; 2016

Under mild tomoderate water deficit conditions maize plants tend to regulate water status  through reductions in leaf expansion rate andconsequently leaf area, transpiration, and growth. However, phenotyping a largenumber of genotypes for growth traits in field conditions under differentscenarios is not straightforward. Recently, the introduction of noveltechniques for high-throughput phenotyping allows reproducible measurements ofdrought-related physiological traits in hundreds of genotypes growing undersemi-controlled conditions. We have analyzeda panel of 255 hybrids in three different experiments with two water scenariosin the phenotyping platform PhenoArch. Plant growth was characterized fromplant images taken 10 to 15 times over the vegetative cycle. Planttranspiration was determined and response curves of leaf expansion rate to soilwater status were established. Lines were genotyped with 354K polymorphic SNPsand GWAS analysis was performed over evaluated traits. Plant growthtraits showed a wide range of variability (Leaf area: from 0.13 to 0.54 m2; Plantbiovolume: from 117 to 577 g) with high heritabilities along the vegetativephase (H²= 0.60-0.91). Variations in plant volume were closely and positivelyrelated to changes in plant evapo-transpiration in all situations. Genotypicvariability for water use efficiency ranged from 52.6 to 91.7 g FW/l. Soilwater deficit caused a large range of responses over the panel. Most sensitivegenotypes stopped leaf expansion at -0.6 MPa, while the less sensitive grew upto -2.5 MPa. These traits were analyzed via genome wide association mapping.This study will allow a better understanding of mechanisms involved in the sensitivityto environmental cues. Because such functional traits are not measurable infield conditions it may give way to interpret GxE interaction observed in fieldnetwork and to assist breeding for drought-prone environments or conditionsassociated to climate changes.