The glycerol-3-phosphate acyltransferase GPAT6 from tomato plays a central role in fruit cutin biosynthesis

Abstract

The thick cuticle covering and embedding the epidermal cells of tomato (Solanum lycopersicum) fruit acts not only as a protective barrier against pathogens and water loss but also influences quality traits such as brightness and postharvest shelf-life. In a recent study, we screened a mutant collection of the miniature tomato cultivar Micro-Tom and isolated several glossy fruit mutants in which the abundance of cutin, the polyester component of the cuticle, was strongly reduced. We employed a newly developed mapping-by-sequencing strategy to identify the causal mutation underlying the cutin deficiency in a mutant thereafter named gpat6-a (for glycerol-3-phosphate acyltransferase6). To this end, a backcross population (BC 1 F 2 ) segregating for the glossy trait was phenotyped. Individuals displaying either a wild-type or a glossy fruit trait were then pooled into bulked populations and submitted to whole-genome sequencing prior to mutation frequency analysis. This revealed that the causal point mutation in the gpat6-a mutant introduces a charged amino acid adjacent to the active site of a GPAT6 enzyme. We further showed that this mutation completely abolished the GPAT activity of the recombinant protein. The gpat6-a mutant showed perturbed pollen formation but, unlike a gpat6 mutant of Arabidopsis (Arabidopsis thaliana), was not male sterile. The most striking phenotype was observed in the mutant fruit, where cuticle thickness, composition, and properties were altered. RNA sequencing analysis highlighted the main processes and pathways that were affected by the mutation at the transcriptional level, which included those associated with lipid, secondary metabolite, and cell wall biosynthesis.

MYB107 and MYB9 Homologs Regulate Suberin Deposition in Angiosperms

“…Expression analysis of GPAT family members in the SlDCR-RNAi fruit revealed that only Solyc04g011600 (SlGPAT5) displayed a significantly altered expression, showing a >350-fold increase in expression compared with wild-type fruit skin ( Figure 1G; Supplemental Figure 5B). Importantly, SlGPAT4 and SlGPAT6, considered to be involved in cutin polymer formation (Yang et al, 2010;Chen et al, 2011b;Petit et al, 2016), showed no change in expression (Supplemental Figure 5).…”

A Specific Gibberellin 20-Oxidase Dictates the Flowering-Runnering Decision in Diploid Strawberry

“…Variant calling (SNPs and InDels) was performed using SAMtools version 1.2 (Li et al, 2009) (http://htslib.org/). Variant analysis and comparison between r bulks and 'Sicile' wild type were performed as previously described (Garcia et al, 2016;Petit et al, 2016). The SNPs identified were further analyzed using WGS of one [r] genotype, 'Baron Solemacher', and one [R] genotype, 'Pawtuckaway', available in GDR (https://www.rosaceae.org/).…”

Glycerol‐3‐phosphate acyltransferase 6 controls filamentous pathogen interactions and cell wall properties of the tomato and Nicotiana benthamiana leaf epidermis

“…However, genes in the ‘cell wall’ gene category responded differently and although we found seven out of 10 also repressed in leaves, none of the five reported by Petit et al . () was induced. Two genes, annotated as pectin methyl esterase inhibitor and cellulose synthase‐like, showed opposite expression dynamics between leaves and fruit.…”