The fruit cuticles of wild tomato species exhibit architectural and chemical diversity, providing a new model for studying the evolution of cuticle function.
The cuticle covers the aerial epidermis of land plants and plays a primary role in water regulation and protection from external stresses. Remarkable species diversity in the structure and composition of its components, cutin and wax, have been catalogued, but few functional or genetic correlations have emerged. Tomato (Solanum lycopersicum) is part of a complex of closely related wild species endemic to the northern Andes and the Galapagos Islands (Solanum Sect. Lycopersicon). Although sharing an ancestor <7 million years ago, these species are found in diverse environments and are subject to unique selective pressures. Furthermore, they are genetically tractable, since they can be crossed with S. lycopersicum, which has a sequenced genome. With the aim of evaluating the relationships between evolution, structure and function of the cuticle, we characterized the morphological and chemical diversity of fruit cuticles of seven species from Solanum Sect. Lycopersicon. Striking differences in cuticular architecture and quantities of cutin and waxes were observed, with the wax coverage of wild species exceeding that of S. lycopersicum by up to seven fold. Wax composition varied in the occurrence of wax esters and triterpenoid isomers. Using a Solanum habrochaites introgression line population, we mapped triterpenoid differences to a genomic region that includes two S. lycopersicum triterpene synthases. Based on known metabolic pathways for acyl wax compounds, hypotheses are discussed to explain the appearance of wax esters with atypical chain lengths. These results establish a model system for understanding the ecological and evolutionary functional genomics of plant cuticles.
Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA.
Trevor H
TH
Yeats
Gregory J
GJ
Buda
Zhonghua
Z
Wang
Noam
N
Chehanovsky
Leonie C
LC
Moyle
Reinhard
R
Jetter
Arthur A
AA
Schaffer
Jocelyn K C
JK
Rose
D005075:Biological Evolution; D002874:Chromosome Mapping; D004952:Esters / Q000378:metabolism; D005638:Fruit / Q000033:anatomy & histology* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics; D006824:Hybridization, Genetic; D008025:Ligases / Q000378:metabolism; D018551:Solanum lycopersicum / Q000033:anatomy & histology* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D019441:Plant Epidermis / Q000033:anatomy & histology* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018526:Plant Transpiration / Q000235:genetics / Q000502:physiology; D014315:Triterpenes / Q000378:metabolism; D014867:Water / Q000378:metabolism; D014885:Waxes / Q000737:chemistry* / Q000378:metabolism
D004952:Esters; D008563:Membrane Lipids; D010940:Plant Proteins; D014315:Triterpenes; D014885:Waxes; D014867:Water; C000521:cutin; D008025:Ligases