Protecting against water loss: analysis of the barrier properties of plant cuticles

Abstract

The cuticle is the major barrier against uncontrolled water loss from leaves, fruits and other primary parts of higher plants. More than 100 mean values for water permeabilities determined with isolated leaf and fruit cuticles from 61 plant species are compiled and discussed in relation to plant organ, natural habitat and morphology. The maximum barrier properties of plant cuticles exceed that of synthetic polymeric films of equal thickness. Cuticular water permeability is not correlated to the thickness of the cuticle or to wax coverage. Relationships between cuticular permeability, wax composition and physical properties of the cuticle are evaluated. Cuticular permeability to water increases on the average by a factor of 2 when leaf surface temperature is raised from 15 degrees C to 35 degrees C. Organic compounds of anthropogenic and biogenic origin may enhance cuticular permeability. The pathway taken by water across the cuticular transport barrier is reviewed. The conclusion from this discussion is that the bulk of water diffuses as single molecules across a lipophilic barrier while a minor fraction travels along polar pores. Open questions concerning the mechanistic understanding of the plant cuticular transport barrier and the role the plant cuticle plays in ensuring the survival and reproductive success of an individual plant are indicated.

Wax Layers onCosmos bipinnatusPetals Contribute Unequally to Total Petal Water Resistance

“…Wax composition controls the cuticular functions, of which blocking excessive water loss is typically considered foremost (Kerstiens, 1996;Riederer and Schreiber, 2001). Studies using the same methods as those employed here showed mean water resistances across species for leaves and fruit of 35 3 10 4 and 1 3 10 4 s m 21 , respectively (Kerstiens, 1996;Schreiber and Riederer, 1996).…”

“…It has been proposed that wax molecules align in parallel in all-trans conformation to form crystalline domains (Small, 1984), which in turn hinder water penetration by forcing individual molecules to weave a tortuous path around them (Reynhardt, 1997;Riederer and Schreiber, 2001). It should be noted that the chain length profiles of different compound classes within C. bipinnatus petal waxes differed drastically, with relatively short chain lengths (mainly C 22 /C 24 ) for fatty acids and primary alcohols and much longer chain lengths (mainly C 27 /C 29 ) for the co-occurring alkanes.…”

“…First, the abaxial wax contains a higher percentage of triterpenoids. As these cyclic compounds likely hamper the formation of crystalline domains, they may consequently increase the permeability of the abaxial surface (Reynhardt, 1997;Riederer and Schreiber, 2001). In addition, the adaxial surface is highly undulated due to the conical cell shapes, which in turn may enhance the effect of the unstirred boundary layer over the surface and add substantially to the water resistance.…”

Dehydration protection provided by a maternal cuticle improves offspring fitness in the moss Funaria hygrometrica

“…The plant cuticle is a critical structure for desiccation protection of sporophytes in vascular plants (Riederer and Schreiber, 2001). Here we demonstrate that the cuticle plays a similar role in bryophytes but, unlike in vascular plants, this cuticle is produced by a maternal gametophyte tissue.…”

“…Cuticle function relating to water loss has been studied primarily in angiosperms and less so in other tracheophyte lineages (e.g. Riederer and Schreiber, 2001;Schreiber and Schönherr, 2009). Cuticles on the leafy gametophytes of mosses may also function in decreasing water loss (i.e.…”