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Accueil du site → Doctorat → Allemagne → Identification of genomic regions of Sorghum bicolor (L.) Moench linked to biofuel-related traits in grain x sweet sorghum recombinant inbred lines

Justus-Liebig-Universität Gießen (2009)

Identification of genomic regions of Sorghum bicolor (L.) Moench linked to biofuel-related traits in grain x sweet sorghum recombinant inbred lines

Shiringani, Amukelani Lacrecia

Titre : Identification of genomic regions of Sorghum bicolor (L.) Moench linked to biofuel-related traits in grain x sweet sorghum recombinant inbred lines

Auteur : Shiringani, Amukelani Lacrecia

Université de soutenance : Justus-Liebig-Universität Gießen

Grade : Doctor of Agricultural Science 2009

Résumé partiel
The increasing demand of food and the rising concerns about climate change and energy security pushes Sorghum bicolor to the top of global agendas. The main attraction is its ability to provide food and animal feed as well as renewable energy products, and industrial commodities. The species comprises grain and sweet sorghum types. Sweet sorghum has major advantages compared to other sugar and biomass crops. Firstly, sorghum is a species showing extensive genetic variation, including drought and heat tolerant genotypes, which enable the usage of marginal land that is not suitable for cultivating other crops. Secondly, competition between the use of land for food or for energy is less because the grains can be used for food or feed while stems can be used for biofuel production. In the current study, field trials and related genetic analysis were carried out to identify major chromosomal regions that are linked to biofuel-related traits. An experimental population of 213 RILs from a cross between grain sorghum (M71) and sweet sorghum (SS79) was planted in 5 environments in Germany in the vegetation periods 2007 and 2008. This population segregates for alleles controlling biomass yield, juice content, sugar content, fibre content, and many other traits. The approach to identify these chromosomal regions was (1) to phenotype the RIL population for the mentioned traits, (2) to construct a genetic map from the RILs, and (3) to correlate the phenotypic data and genetic map informations. The phenotypic data was analysed for individual location and environments (years*location) using mixed model from SAS® 9.1 version. Genotypes were treated as fixed effects while all other components were treated as random effects. Regarding, sugar-related traits, we analysed brix, glucose content, sucrose content, and sugar content, measured stem diameter, stem juice weight, plant height and fresh panicle weight, and counted the days to anthesis and the number of tillers per plant. We partitioned the variance components as genetic, location, year, genetic x location, genetic x year, location x year, genetic x location x year, and harvest date. The results showed that although location contributed highly to the phenotype in terms of percentage, it was not a significant source of variance. The interaction between genotypes and environment was observed in most traits except for stem juice weight, fresh panicle weight and glucose content. Genetic variance contributed small but significant to the phenotypic variance. And thus the heritability estimates were moderate to high in all traits except stem juice weight (H2=0.18). Pearson correlation estimates showed that these traits were significantly correlated with each other. Flowering dates correlated with all the traits while number of tillers only positively correlated with stem juice weight, and negatively correlated with sugar content and flowering dates.

Mots Clés : Sorghum , Biofuel , QTL , sugar , fibre , epistasis

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Page publiée le 17 mars 2011, mise à jour le 8 janvier 2019