The impact of drought on wheat leaf cuticle properties

Huihui Bi,Nikolai Borisjuk,Penny J Tricker,Peter Langridge,Sergiy Lopato,Nataliya Kovalchuk

doi:10.1186/s12870-017-1033-3

Abstract

BackgroundThe plant cuticle is the outermost layer covering aerial tissues and is composed of cutin and waxes. The cuticle plays an important role in protection from environmental stresses and glaucousness, the bluish-white colouration of plant surfaces associated with cuticular waxes, has been suggested as a contributing factor in crop drought tolerance. However, the cuticle structure and composition is complex and it is not clear which aspects are important in determining a role in drought tolerance. Therefore, we analysed residual transpiration rates, cuticle structure and epicuticular wax composition under well-watered conditions and drought in five Australian bread wheat genotypes, Kukri, Excalibur, Drysdale, RAC875 and Gladius, with contrasting glaucousness and drought tolerance.ResultsSignificant differences were detected in residual transpiration rates between non-glaucous and drought-sensitive Kukri and four glaucous and drought-tolerant lines. No simple correlation was found between residual transpiration rates and the level of glaucousness among glaucous lines. Modest differences in the thickness of cuticle existed between the examined genotypes, while drought significantly increased thickness in Drysdale and RAC875. Wax composition analyses showed various amounts of C31 β-diketone among genotypes and increases in the content of alkanes under drought in all examined wheat lines.ConclusionsThe results provide new insights into the relationship between drought stress and the properties and structure of the wheat leaf cuticle. In particular, the data highlight the importance of the cuticle’s biochemical makeup, rather than a simple correlation with glaucousness or stomatal density, for water loss under limited water conditions.

Highlights

The plant cuticle is the outermost layer covering aerial tissues and is composed of cutin and waxes
After 2 hours, the water loss rates became stable in all five lines and could be considered residual transpiration rates (RTRs), which are primarily contributed by the cuticle
Similar to results obtained for WW wheat plants, the RTRs of Kukri plants grown under drought conditions were higher than those of DR RAC875, Drysdale or Gladius (Fig. 1b), the difference was less pronounced compared to the WW experiments (Fig. 1a)

Summary

Introduction

The plant cuticle is the outermost layer covering aerial tissues and is composed of cutin and waxes. The cuticle plays an important role in protection from environmental stresses and glaucousness, the bluish-white colouration of plant surfaces associated with cuticular waxes, has been suggested as a contributing factor in crop drought tolerance. The cuticle structure and composition is complex and it is not clear which aspects are important in determining a role in drought tolerance. We analysed residual transpiration rates, cuticle structure and epicuticular wax composition under well-watered conditions and drought in five Australian bread wheat genotypes, Kukri, Excalibur, Drysdale, RAC875 and Gladius, with contrasting glaucousness and drought tolerance. The wheat cuticle is a 0.1–10 μm thick membrane composed principally of a polyester matrix intertwined with a range of long chain hydrocarbons. The waxes are typically a complex mixture of derivatives of very-long-chain saturated

Methods

Results

Discussion

Conclusion