The Formation and Function of Plant Cuticles

Abstract

The plant cuticle is an extracellular hydrophobic layer that covers the aerial epidermis of all land plants, providing protection against desiccation and external environmental stresses. The past decade has seen considerable progress in assembling models for the biosynthesis of its two major components, the polymer cutin and cuticular waxes. Most recently, two breakthroughs in the long-sought molecular bases of alkane formation and polyester synthesis have allowed construction of nearly complete biosynthetic pathways for both waxes and cutin. Concurrently, a complex regulatory network controlling the synthesis of the cuticle is emerging. It has also become clear that the physiological role of the cuticle extends well beyond its primary function as a transpiration barrier, playing important roles in processes ranging from development to interaction with microbes. Here, we review recent progress in the biochemistry and molecular biology of cuticle synthesis and function and highlight some of the major questions that will drive future research in this field.

Rice TUTOU1 Encodes a Suppressor of cAMP Receptor-Like Protein That Is Important for Actin Organization and Panicle Development

“…Considering that the panicle apical degeneration phenotype of tut1 is closely associated with cuticle disorganization and deficiency, it is reasonable to presume that the formation of the cuticle affects panicle development in rice. The complex regulation of cuticle formation includes vesicle trafficking, fatty acid metabolism, and transport processes (Yeats and Rose, 2013). Vesicle trafficking that can be regulated by F-actin is important for wax secretion from epidermal cells in Arabidopsis (McFarlane et al, 2014).…”

Analyses of Tomato Fruit Brightness Mutants Uncover Both Cutin-Deficient and Cutin-Abundant Mutants and a New Hypomorphic Allele of GDSL Lipase

“…Mechanisms of transport of the cutin monomers and their assembly into the cuticle remain largely unknown. The plasma membrane ATP-binding cassette transporters have been implicated in the transport of both wax and cutin to the apoplast, whereas lipid transfer proteins very likely contribute to the transport of cutin monomers through the cell wall to the cutin layer (Yeats and Rose, 2013). The implication of enzymes of the GDSL lipase family in cutin assembly, which is long suspected (Reina et al, 2007;Mintz-Oron et al, 2008), was recently demonstrated in tomato (Solanum lycopersicum; Girard et al, 2012;Yeats et al, 2012a).…”

“…Several of their downstream targets involved in cutin synthesis, modification, and assembly, as well as in cell wall formation and structure and in epidermal cell patterning (Shi et al, 2013), have been identified. Other transcription factors of the MYB protein family, Homeodomain-leucine-zipper (HD-ZIP) IV family, and WW domain protein were shown to control cuticle formation, some of which and were suggested to take part in a regulatory network controlling epidermal cell patterning (Yeats and Rose, 2013).…”

“…In recent years, availability of the Arabidopsis (Arabidopsis thaliana) genome sequence, high-throughput gene expression analysis tools, and mutant collections enabled deciphering the biosynthetic pathways and transport networks involved in cutin, suberin, and wax biosynthesis (Pollard et al, 2008;Li-Beisson et al, 2009;Beisson et al, 2012;Yeats and Rose, 2013). The synthesis of the cutin monomer starts with the synthesis of long chain fatty acids in the plastids.…”

“…Wax biosynthesis involves several steps including the synthesis of VLCFAs through a multi-enzyme fatty acid elongase complex and the synthesis of VLCFA derivatives through either the alcohol-forming pathway, which gives rise to primary alcohols and wax esters, or the alkane-forming pathway producing aldehydes, alkanes, secondary alcohols, and ketones. Export of wax through plasma membrane occurs via ATP-binding cassette transporters and glycosylphosphotidylinositol-anchored lipid transfer proteins (Kunst and Samuels, 2009;Yeats and Rose, 2013).…”