Thesis defense: Léa Barreda
Thursday, October 31st 2024, 2 pm, INRAE, Versailles
Characterization of the seed specialized metabolome landscape and plasticity in Brassicaceae species
Specialized metabolites (SMs) play crucial roles in the interaction of plants and seeds with their environment. SM modifications greatly contribute to SM diversity and activities. Despite their importance for seed quality, the study of the impact of the environment on the synthesis, modification and accumulation of SMs in seeds has been neglected. Seeds accumulate both beneficial and antinutritional SMs with a large range of biological and ecological roles and significant importance for human and animal nutrition, and other industrial uses. Hence, study the diversity, distribution and regulation of SMs in seeds upon environmental stresses is of major relevance, especially in the current context of climate change. This is particularly true for seeds of Brassicaceae species, which include both model and crop species that are widely cultivated across the world and used/consumed as vegetables, fodder, or oilseeds. These species show diverse SM composition and distribution, which makes them valuable models to study the impacts of environmental stresses on seed SMs.
This Ph.D. project aimed at characterizing the diversity and plasticity of seed specialized metabolites in Brassicaceae species under environmental stresses by using multi-omic, molecular biology and reverse genetic approaches.
In a first study, the diversity and plasticity of seed SMs from several Camelina sativa genotypes cultivated in open field for several consecutive years were assessed. The results obtained showed that the accumulation of SMs in Camelina seeds was more impacted by the environmental conditions rather than the genotype, and that the plasticity of SMs was higher compared to those of major seed storage compounds, including oil, proteins, and other primary metabolites.
A second study aimed to evaluate the impact of stress conditions on developing seeds of the model species Arabidopsis thaliana. Heat stress (HS) was found to induce the strongest changes in seed specialized metabolome, compared to drought stress and copper chloride stress (inducing oxidative stress and mimicking biotic stress effects). Hence, the study has been focused on studying the effect of HS on specialized metabolome during Arabidopsis seed development by using multi-omic analyses (untargeted metabolomic and transcriptomic analyses). A wide range of SMs and genes were affected by HS during seed development. Among them, glucosinolates (GSLs) related to ALKENYL HYDROXALKYL PRODUCING 3 (AOP3) GSL hydroxylase enzyme were strongly induced by HS. Besides, several thioglucose sinapoylated and benzoylated GSLs were identified and reported for the first time. Untargeted metabolomic and physiological analyses were performed with several Arabidopsis mutants for GSL-related genes and wild-type genotype, in order to elucidate the synthesis, modifications, regulation and functions of those thioglucose acylated GSLs. The obtained results showed that the acyltransferase SERINE CARBOXYPEPTIDASE LIKE 17 (SCPL17) and BENZOYLGLUCOSINOLATE 1 (BZO1) are involved in the sinapoylation and/or benzoylation of GSL thioglucose moieties and that thioglucose benzoylated and sinapoylated GSLs are involved in Arabidopsis HS responses in seeds.
Finally, to study and characterize seed SM distribution, multi-omic analyses have been performed on C. sativa seed embryo (SE) and seed coat and endosperm (SCE) tissues from developing and germinating seeds. The data obtained revealed some specific accumulation pattern of GSLs and related degradation products in the different seed tissues of C. sativa, A. thaliana and Brassica napus species that provide valuable complementary information to the previously described work about GSL functions and activities. In particular, the short methionine derived (Met-de) GSLs (<8C) accumulated in SE, while longer Met-de GSLs (>7C) accumulated in SC. Differently, GSL degradation products accumulation showed diverse accumulation patterns in the three Brassicaceae species.
Specialized metabolites (SMs) play crucial roles in the interaction of plants and seeds with their environment. SM modifications greatly contribute to SM diversity and activities. Despite their importance for seed quality, the study of the impact of the environment on the synthesis, modification and accumulation of SMs in seeds has been neglected. Seeds accumulate both beneficial and antinutritional SMs with a large range of biological and ecological roles and significant importance for human and animal nutrition, and other industrial uses. Hence, study the diversity, distribution and regulation of SMs in seeds upon environmental stresses is of major relevance, especially in the current context of climate change. This is particularly true for seeds of Brassicaceae species, which include both model and crop species that are widely cultivated across the world and used/consumed as vegetables, fodder, or oilseeds. These species show diverse SM composition and distribution, which makes them valuable models to study the impacts of environmental stresses on seed SMs.
This Ph.D. project aimed at characterizing the diversity and plasticity of seed specialized metabolites in Brassicaceae species under environmental stresses by using multi-omic, molecular biology and reverse genetic approaches.
In a first study, the diversity and plasticity of seed SMs from several Camelina sativa genotypes cultivated in open field for several consecutive years were assessed. The results obtained showed that the accumulation of SMs in Camelina seeds was more impacted by the environmental conditions rather than the genotype, and that the plasticity of SMs was higher compared to those of major seed storage compounds, including oil, proteins, and other primary metabolites.
A second study aimed to evaluate the impact of stress conditions on developing seeds of the model species Arabidopsis thaliana. Heat stress (HS) was found to induce the strongest changes in seed specialized metabolome, compared to drought stress and copper chloride stress (inducing oxidative stress and mimicking biotic stress effects). Hence, the study has been focused on studying the effect of HS on specialized metabolome during Arabidopsis seed development by using multi-omic analyses (untargeted metabolomic and transcriptomic analyses). A wide range of SMs and genes were affected by HS during seed development. Among them, glucosinolates (GSLs) related to ALKENYL HYDROXALKYL PRODUCING 3 (AOP3) GSL hydroxylase enzyme were strongly induced by HS. Besides, several thioglucose sinapoylated and benzoylated GSLs were identified and reported for the first time. Untargeted metabolomic and physiological analyses were performed with several Arabidopsis mutants for GSL-related genes and wild-type genotype, in order to elucidate the synthesis, modifications, regulation and functions of those thioglucose acylated GSLs. The obtained results showed that the acyltransferase SERINE CARBOXYPEPTIDASE LIKE 17 (SCPL17) and BENZOYLGLUCOSINOLATE 1 (BZO1) are involved in the sinapoylation and/or benzoylation of GSL thioglucose moieties and that thioglucose benzoylated and sinapoylated GSLs are involved in Arabidopsis HS responses in seeds.
Finally, to study and characterize seed SM distribution, multi-omic analyses have been performed on C. sativa seed embryo (SE) and seed coat and endosperm (SCE) tissues from developing and germinating seeds. The data obtained revealed some specific accumulation pattern of GSLs and related degradation products in the different seed tissues of C. sativa, A. thaliana and Brassica napus species that provide valuable complementary information to the previously described work about GSL functions and activities. In particular, the short methionine derived (Met-de) GSLs (<8C) accumulated in SE, while longer Met-de GSLs (>7C) accumulated in SC. Differently, GSL degradation products accumulation showed diverse accumulation patterns in the three Brassicaceae species.
Supervisor: Massimiliano Corso - INRAE, IJPB, Versailles
Co-Supervisor: Loïc Lepiniec - INRAE, IJPB, Versailles and Grégory Mouille - INRAE, IJPB, Versailles, ACCI team
Members of the jury:
> Julia Buitink (Rapportrice) – INRAE, IRHS, Angers
> Alain Bouchereau (Rapporteur) - Université de Rennes, INRAE, IGEPP
> Muriel Viaud (Examinatrice) – INRAE, BIOGER, Palaiseau
> Nathalie Guivarc’h (Examinatrice) - Université de Tours, BBV
> Hugues Renault (Examinateur) - CNRS, IBMP, Strasbourg
To attend, contact Massimiliano Corso
Research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.
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