Cloning and Characterization of the dominant Inhibitor of Wax 1 (Iw1) gene in polyploid wheat

The Inhibitor of Wax 1 (Iw1) is a dominant inhibitor of glaucousness, the whitish waxy bloom present on the aerial surfaces of a wheat plant: The presence of Iw1 leads to non-glaucousness. In previous work a doubled-haploid population segregating for the presence of the Iw1 locus was created. The non-glaucous doubled-haploid lines of this population showed increases in yield and green-canopy duration under UK conditions compared to their glaucous counterparts by on average 4.15% and 1.5 days, respectively. The aim of this study was to identify Iw1 via a positional cloning approach and to characterize its effects on yield and green-canopy duration in a field-grown set of glaucous and non-glaucous Near Isogenic Lines (NILs). In addition a number of physiological experiments were carried out on these NILs to determine the effects of non-glaucousness on light reflectance and transmission as well as on water-use efficiency (WUE). Finally, the composition of surface waxes in glaucous and non-glaucous NILs was elucidated using a combination of electron microscopy and biochemical methods. Here, we have fine-mapped Iw1 to a 0.42-cM interval on the short arm of chromosome 2B and we have constructed a physical map, which is currently 1,200 kb in size. Gene models were predicted in silico and we have begun to test candidate genes using allelic diversity and expression analysis. The results of our physiological experiments clearly show a reduction in light reflectance and a possible increase in light transmission through the canopy leaves in non-glaucous NILs. We could not detect a negative effect on WUE in field-grown NILs nor did we identify significant increases in yield. A consistent extension in green-canopy duration was associated with the Iw1 region, although not significant in all years. Our analysis of the composition of surface waxes has shown that only a discrete type of wax, the β–diketone aliphatics, is being inhibited by Iw1.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2013

Author dc:creator

• Adamski, Nikolai

Language dc:language

en