The effect of non-glaucousness, as conferred by Inhibitor of Wax 1, on physiology and yield of UK wheat

• Main Author: Frizell-Armitage, Amelia
• Published: University of East Anglia 2016
• Subjects: 633.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687941

As the first barrier to the external environment, the epicuticular waxes have a number of key roles in plant physiology. Although the wheat wild progenitors display a diversity of epicuticular wax phenotypes, the glaucous (visible wax) phenotype dominates cultivated varieties. However, the UK winter wheat variety Shamrock is unusual in that it exhibits a non-glaucous phenotype, conferred by the wild emmer gene Inhibitor of Wax 1 (Iw1). UK field trials with Shamrock associated a yield advantage of 4.15% with Iw1. This PhD tests the hypothesis that Iw1 imparts an advantage for wheat yield and physiology in the UK. Crossing Shamrock with six glaucous UK winter wheat varieties (Malacca, Alchemy, Hereward, Xi19, Robigus and Einstein) created non-glaucous near isogenic lines (NILs) with Iw1. NILs were grown at multiple field trial locations in the east of England over four years. A long-term shade trial reducing incoming light by 40 and 60% was also carried out in 2014. Yield, and various physiological components including water use efficiency (WUE) and spectral properties, were measured. Iw1 reduced flag leaf photosynthetically active radiation (PAR) reflectance by 15-40% and canopy reflectance by 12-20% (p<0.05). Despite this, Iw1 did not affect flag leaf PAR absorbance or canopy temperature, and conferred no advantage under long-term shading. Furthermore, there was no difference between NILs in photoinhibition following an extended period of high light stress. Iw1 did not affect WUE or yield. However, non-glaucous Hereward and Alchemy NILs yielded 4.96±1.15% (p<0.001) and 2.59±1.01% (p=0.045) more than their glaucous counterparts, although this advantage did not map to Iw1. Iw1 offered no advantage to UK winter wheat under normal UK growing conditions, nor under long-term shading. However, the yield advantage associated with the Iw1 introgression in Hereward and Alchemy is significant within a backdrop of plateauing wheat yields and worth pursuing.