Water deficits in wheat: fructan exohydrolase (1-FEH) mRNA expression and relationship to soluble carbohydrate concentrations in two varieties

Terminal drought is a risk for wheat production in many parts of the world. Robust physiological traits for resilience would enhance the preselection of breeding lines in drought-prone areas. Three pot experiments were undertaken to characterize stem water-soluble carbohydrate (WSC), fructan exohydrolase expression, grain filling and leaf gas exchange in wheat (Triticum aestivum) varieties, Kauz and Westonia, which are considered to be drought-tolerant. Water deficit accelerated the remobilization of stem WSC in Westonia but not in Kauz. The profile of WSC accumulation and loss was negatively correlated with the mRNA concentration of 1-FEH, especially 1-FEH w3 (1-FEH-6B). Under water deficit, Westonia showed lower concentrations of WSC than Kauz but did not show a corresponding drop in grain yield. The results from pot experiments suggest that stem WSC concentration is not, on its own, a reliable criterion to identify potential grain yield in wheat exposed to water deficits during grain filling. The expression of 1-FEH w3 may provide a better indicator when linked to osmotic potential and green leaf retention, and this requires validation in field-grown plants. New Phytologist (2009) 181: 843-850doi: 10.1111/j.1469-8137.2008.02713.x.