The identification of cutin synthase: formation of the plant polyester cutin

Abstract

A hydrophobic cuticle consisting of waxes and the polyester cutin covers the aerial epidermis of all land plants, providing essential protection from desiccation and other stresses. We have determined the enzymatic basis of cutin polymerization through characterization of a tomato extracellular acyltransferase, CD1, and its substrate, 2-mono(10,16-dihydroxyhexadecanoyl)glycerol (2-MHG). CD1 has in vitro polyester synthesis activity and is required for cutin accumulation in vivo, indicating that it is a cutin synthase.

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

“…No mutation in this gene was detected upon sequencing. The second encodes an acyl-transferase of the GDSL esterase/lipase protein family recently shown to be involved in the extracellular deposition of cutin in tomato fruit (Girard et al, 2012;Yeats et al, 2012b). The current locus name of Solyc11g006250 (1,004,368 to 1,006,899 nucleotides on chromosome 11) in the Solanaceae SGN database is GDSL2, whereas its given names were previously SlGDSL1 (Girard et al, 2012) and cutin synthase CD1 (Yeats et al, 2012b).…”

“…We further focused on cutin mutants because cutin load is possibly the major factor controlling fruit brightness in tomato (Girard et al, 2012;Nadakuduti et al, 2012;Yeats et al, 2012b), and the possible effects of wax changes on glossiness have already been well described in Arabidopsis (Chen et al, 2003;Aharoni et al, 2004;Bourdenx et al, 2011). One way to identify the possible origin of the mutation is to combine the wealth of information now available on cuticle biosynthesis and regulation with the data on fruit surface chemistry.…”

“…7B). Because a mutated allele of SlGDSL2 was already described in tomato (Yeats et al, 2012b), the P15C12 mutant is thereafter named gdsl2-b. As in other introns belonging to the major class of introns processed by the U2 spliceosome, the splice site sequences of intron 4 from SlGDSL2 gene fit the canonical GT-AG consensus borders, where the nearly invariant GT dinucleotide is at the 59 end and the AG dinucleotide at the 39 end of the intron.…”

“…Fruit brightness modifications could not be attributed to a single cause but rather to combinations of various and sometimes opposite alterations of fruit cuticle. We further identified the mutation underlying a glossy cutin-deficient mutant by genetic mapping of the corresponding cuticle-associated traits and discovered a novel allele of the tomato GDSL lipase involved in cutin polymerization (Girard et al, 2012;Yeats et al, 2012b). Thus, our study highlights how the exploitation of artificially induced genetic diversity and of genomic tools currently available in tomato can efficiently contribute to the study of cuticle biosynthesis and properties in plants.…”

“…The thick and easy-to-isolate peel from tomato has long been used for studying the biomechanical properties of plant cuticle (Domínguez et al, 2011). In recent years, the increased availability of tomato genomic resources, including saturated genetic linkage maps, markers, and very recently the tomato genomic sequence (Tomato Genome Consortium, 2012), offered unprecedented possibilities for exploiting tomato as a model for studying plant cuticle (Hovav et al, 2007;Adato et al, 2009;Isaacson et al, 2009;Girard et al, 2012;Yeats et al, 2012b;Shi et al, 2013). To fully explore the relationships between cuticle composition and cuticle properties and to discover new genes and functions, new sources of genetic variability affecting tomato genes involved in wax, cutin, and suberin synthesis and regulation are required.…”