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

The leaf outer epidermal cell wall acts as a barrier against pathogen attack and desiccation, and as such is covered by a cuticle, composed of waxes and the polymer cutin. Cutin monomers are formed by the transfer of fatty acids to glycerol by glycerol-3-phosphate acyltransferases, which facilitate their transport to the surface. The extent to which cutin monomers affect leaf cell wall architecture and barrier properties is not known. We report a dual functionality of pathogen-inducible GLYCEROL-3-PHOSPHATE ACYLTRANSFERASE 6 (GPAT6) in controlling pathogen entry and cell wall properties affecting dehydration in leaves. Silencing of Nicotiana benthamiana NbGPAT6a increased leaf susceptibility to infection by the oomycetes Phytophthora infestans and Phytophthora palmivora, whereas overexpression of NbGPAT6a-GFP rendered leaves more resistant. A loss-of-function mutation in tomato SlGPAT6 similarly resulted in increased susceptibility of leaves to Phytophthora infection, concomitant with changes in haustoria morphology. Modulation of GPAT6 expression altered the outer wall diameter of leaf epidermal cells. Moreover, we observed that tomato gpat6-a mutants had an impaired cell wall-cuticle continuum and fewer stomata, but showed increased water loss. This study highlights a hitherto unknown role for GPAT6-generated cutin monomers in influencing epidermal cell properties that are integral to leaf-microbe interactions and in limiting dehydration.Royal Society (RG120398, UF110073, UF160413) and the Gatsby Charitable Foundation (GAT3395/GLD) Plant Genome Research Program of the US National Science Foundation (IOS-1339287) Agriculture and Food Research Initiative of the US Department of Agriculture (2016-67013-24732)

Genetic improvement of tomato by targeted control of fruit softening

Controlling the rate of softening to extend shelf life was a key target for researchers engineering genetically modified (GM) tomatoes in the 1990s, but only modest improvements were achieved. Hybrids grown nowadays contain 'non-ripening mutations' that slow ripening and improve shelf life, but adversely affect flavor and color. We report substantial, targeted control of tomato softening, without affecting other aspects of ripening, by silencing a gene encoding a pectate lyase

The Glycerol-3-Phosphate Acyltransferase GPAT6 from Tomato Plays a Central Role in Fruit Cutin Biosynthesis.

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 (BC1F2) 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

The Glycerol-3-Phosphate Acyltransferase GPAT6 from Tomato Plays a Central Role in Fruit Cutin Biosynthesis.

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 (BC1F2) 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

The genome of the stress-tolerant wild tomato species Solanum pennellii

Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomato Solanum lycopersicum1. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance2. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm.Fil: Bolger, Anthony. Aachen University; Alemania. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Scossa, Federico. Institut Max Planck fur Molekulare Physiologie; Alemania. Consiglio per la Ricerca in Agricoltura e l'Analisi del l'Economía Agraria; ItaliaFil: Bolger, Marie E.. Institut Max Planck fur Molekulare Physiologie; Alemania. Forschungszentrum Jülich; AlemaniaFil: Lanz, Christa. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Maumus, Florian. Institut National de la Recherche Agronomique; FranciaFil: Tohge, Takayuki. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Quesneville, Hadi. Institut National de la Recherche Agronomique; FranciaFil: Alseekh, Saleh. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Sørensen, Iben. Cornell University; Estados UnidosFil: Lichtenstein, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Fich, Eric A.. Cornell University; Estados UnidosFil: Conte, Mariana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas; ArgentinaFil: Keller, Heike. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Schneeberger, Korbinian. Institut Max Planck fur Molekulare Physiologie; Alemania. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Schwacke, Rainer. Institut Max Planck fur Molekulare Physiologie; Alemania. Forschungszentrum Jülich; AlemaniaFil: Ofner, Itai. The Hebrew University of Jerusalem; IsraelFil: Vrebalov, Julia. Cornell University; Estados UnidosFil: Xu, Yimin. Cornell University; Estados UnidosFil: Osorio, Sonia. Institut Max Planck fur Molekulare Physiologie; Alemania. Universidad de Málaga; EspañaFil: Aflitos, Saulo Alves. University of Agriculture Wageningen; Países BajosFil: Schijlen, Elio. University of Agriculture Wageningen; Países BajosFil: Jiménez Goméz, José M.. Max Planck Institute for Plant Breeding Research; Alemania. Institut National de la Recherche Agronomique; FranciaFil: Ryngajllo, Malgorzata. Institut Max Planck fur Molekulare Physiologie; AlemaniaFil: Kimura, Seisuke. University of California at Davis; Estados UnidosFil: Kumar, Ravi. University of California at Davis; Estados UnidosFil: Koenig, Daniel. Institut Max Planck fur Molekulare Physiologie; Alemania. University of California at Davis; Estados UnidosFil: Headland, Lauren R.. University of California at Davis; Estados UnidosFil: Maloof, Julin N.. University of California at Davis; Estados UnidosFil: Sinha, Neelima. University of California at Davis; Estados UnidosFil: Van Ham, Roeland C. H. J.. University of Agriculture Wageningen; Países Bajo

The genome of the stress-tolerant wild tomato species Solanum pennellii.

Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomato Solanum lycopersicum. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm

The genome of the stress-tolerant wild tomato species Solanum pennellii

Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomato Solanum lycopersicum. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm