Barley (Hordeum vulgare L.) is one of the most important crops, with a worldwide grain production of more than 137,98 mln tons per year, 41% of which are produced in Europe. Barley production is threatened by climate change and the associated growing frequency of extreme weather events which results for example in increased lodging. Morphological culm features have been linked to lodging resistance and biomass production in rice and wheat, but the genetic architecture underlying culm traits has not been investigated in barley. Within the ClimBar project, the objective of my PhD research was to dissect natural genetic variation related to culm morphological traits in barley through association mapping on a collection of 198 diverse spring barley cultivars. As a critical region for lodging, we targeted the structure of 2nd basal internode from main stem: internode samples were collected in 2016 and 2017 from field-grown plants at dough stage (in Italy) and pre-harvest stage in four European locations (Spain, Italy, Finland and United Kingdom). Phenotypic data for culm diameter and culm wall thickness were obtained using a newly developed image analysis protocol based on ImageJ software. The number of vascular bundles from dough stage samples was also counted. Data for plant height, days to heading, lodging, and grain yield were also considered for further comparisons. Statistical analyses indicated the existence of significant genetic variation for the studied traits as supported by high heritability values. Combined analysis of variance indicated the existence of interaction between genotype and environment and this was mainly due to location by genotype, while the interaction due to year was less important, indicating the stability of the genotypes across years within the same location. Internode diameter and other culm related traits showed interesting correlations with other agronomical features, describing a complex system of interactions among the different plant organs and how they respond to the surrounding environment. Genome-wide marker data from a 50k iSelect Infinium SNP panel were used to run Genome-Wide Association Studies (GWAS) for plant height as validation trait, recovering markers in close proximity to well-known genes. GWAS revealed significant marker-trait associations for culm traits located within genomic regions harboring potential candidate genes mainly involved in the modification of cell wall composition and interacting with hormonal pathways. However, some associations were location-specific, due to the existence of GxE interactions for the traits under study. Together, our results provide the first insights into the genetic basis of culm morphology in barley and support the value of natural genetic diversity for the improvement of barley yield under climate change.

CHARACTERIZATION AND DISSECTION OF NATURAL GENETIC DIVERSITY FOR CULM TRAITS IN BARLEY (HORDEUM VULGARE L.) / G. Bretani ; tutor: Rossini Laura; cotutor: Shaaf Salar, Tondelli Alessandro ; cooordinator: D. Bassi. - : . DIPARTIMENTO DI SCIENZE AGRARIE E AMBIENTALI - PRODUZIONE, TERRITORIO, AGROENERGIA, 2019 Feb 06. ((31. ciclo, Anno Accademico 2018. [10.13130/bretani-gianluca_phd2019-02-06].

CHARACTERIZATION AND DISSECTION OF NATURAL GENETIC DIVERSITY FOR CULM TRAITS IN BARLEY (HORDEUM VULGARE L.)

G. Bretani
2019-02-06

Abstract

Barley (Hordeum vulgare L.) is one of the most important crops, with a worldwide grain production of more than 137,98 mln tons per year, 41% of which are produced in Europe. Barley production is threatened by climate change and the associated growing frequency of extreme weather events which results for example in increased lodging. Morphological culm features have been linked to lodging resistance and biomass production in rice and wheat, but the genetic architecture underlying culm traits has not been investigated in barley. Within the ClimBar project, the objective of my PhD research was to dissect natural genetic variation related to culm morphological traits in barley through association mapping on a collection of 198 diverse spring barley cultivars. As a critical region for lodging, we targeted the structure of 2nd basal internode from main stem: internode samples were collected in 2016 and 2017 from field-grown plants at dough stage (in Italy) and pre-harvest stage in four European locations (Spain, Italy, Finland and United Kingdom). Phenotypic data for culm diameter and culm wall thickness were obtained using a newly developed image analysis protocol based on ImageJ software. The number of vascular bundles from dough stage samples was also counted. Data for plant height, days to heading, lodging, and grain yield were also considered for further comparisons. Statistical analyses indicated the existence of significant genetic variation for the studied traits as supported by high heritability values. Combined analysis of variance indicated the existence of interaction between genotype and environment and this was mainly due to location by genotype, while the interaction due to year was less important, indicating the stability of the genotypes across years within the same location. Internode diameter and other culm related traits showed interesting correlations with other agronomical features, describing a complex system of interactions among the different plant organs and how they respond to the surrounding environment. Genome-wide marker data from a 50k iSelect Infinium SNP panel were used to run Genome-Wide Association Studies (GWAS) for plant height as validation trait, recovering markers in close proximity to well-known genes. GWAS revealed significant marker-trait associations for culm traits located within genomic regions harboring potential candidate genes mainly involved in the modification of cell wall composition and interacting with hormonal pathways. However, some associations were location-specific, due to the existence of GxE interactions for the traits under study. Together, our results provide the first insights into the genetic basis of culm morphology in barley and support the value of natural genetic diversity for the improvement of barley yield under climate change.
ROSSINI, LAURA
SHAAF, SALAR
BASSI, DANIELE
ROSSINI, LAURA
TONDELLI, ALESSANDRO
BARELEY; GENOMICS; GWAS; AMMI; CULM; DIAMETER; THICKNESS
Settore AGR/07 - Genetica Agraria
CHARACTERIZATION AND DISSECTION OF NATURAL GENETIC DIVERSITY FOR CULM TRAITS IN BARLEY (HORDEUM VULGARE L.) / G. Bretani ; tutor: Rossini Laura; cotutor: Shaaf Salar, Tondelli Alessandro ; cooordinator: D. Bassi. - : . DIPARTIMENTO DI SCIENZE AGRARIE E AMBIENTALI - PRODUZIONE, TERRITORIO, AGROENERGIA, 2019 Feb 06. ((31. ciclo, Anno Accademico 2018. [10.13130/bretani-gianluca_phd2019-02-06].
Doctoral Thesis
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/619737
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