Unraveling Cuticle Formation, Structure, and Properties by Using Tomato Genetic Diversity.

Johann Petit,Nicolas Reynoud,Christophe Rothan,Didier Marion,Bénédicte Bakan,Marc Lahaye,Cécile Bres

doi:10.3389/fpls.2021.778131

Abstract

The tomato (Solanum lycopersicum) fruit has a thick, astomatous cuticle that has become a model for the study of cuticle formation, structure, and properties in plants. Tomato is also a major horticultural crop and a long-standing model for research in genetics, fruit development, and disease resistance. As a result, a wealth of genetic resources and genomic tools have been established, including collections of natural and artificially induced genetic diversity, introgression lines of genome fragments from wild relatives, high-quality genome sequences, phenotype and gene expression databases, and efficient methods for genetic transformation and editing of target genes. This mini-review reports the considerable progresses made in recent years in our understanding of cuticle by using and generating genetic diversity for cuticle-associated traits in tomato. These include the synthesis of the main cuticle components (cutin and waxes), their role in the structure and properties of the cuticle, their interaction with other cell wall polymers as well as the regulation of cuticle formation. It also addresses the opportunities offered by the untapped germplasm diversity available in tomato and the current strategies available to exploit them.

Highlights

Cultivated tomato (Solanum lycopersicum L.) is a major horticultural crop that has long been a model for the Solanaceae crop species and for fleshy fruit development and disease resistance (Rothan et al, 2019)
Semi-quantitative RNA-seq coupled with laser microdissection (LMD) allowed exhaustive inventory of gene transcripts expressed in plant tissues, including outer and inner fruit epidermis (Matas et al, 2011)
Thanks to its thick astomatous fruit cuticle that is easy to study and the wealth of mutants and lines with altered expression of cuticle-related genes already available, tomato provides an excellent model for deciphering the molecular determinants of cuticle formation, structure, and properties

Summary

INTRODUCTION

Cultivated tomato (Solanum lycopersicum L.) is a major horticultural crop that has long been a model for the Solanaceae crop species (tomato, potato, eggplant, pepper ...) and for fleshy fruit development and disease resistance (Rothan et al, 2019). Since the cuticle is a major component of the fruit skin and is associated with a wide diversity of major breeding targets including fruit appearance (color, glossiness, regularity...) and properties (shelf-life, fungal resistance, and cracking; Bargel and Neinhuis, 2005; Petit et al, 2017; Lara et al, 2019), it has received considerable attention in recent years In this field of study, tomato holds a prominent position among fleshy fruits because of its thick, astomatous, and easyto-peel cuticle (Petit et al, 2017). Semi-quantitative RNA-seq coupled with laser microdissection (LMD) allowed exhaustive inventory of gene transcripts expressed in plant tissues, including outer and inner fruit epidermis (Matas et al, 2011) Another original transcriptomebased approach used a chimera between two tomato species displaying genotype-specific E1 cell layer to provide a reference catalog of epidermis-specific genes (Filippis et al, 2013).

OE OE

RNAi silencing

Histone methylation

Using Natural Genetic Diversity for Linking Cuticle Phenotype to Gene

CONCLUDING REMARKS AND PERSPECTIVES