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Università di Parma (2016)

Isolation, characterization and discovery of new alleles of sHsp genes in durum wheat (Triticum durum Desf.)

Comastri, Alessia

Titre : Isolation, characterization and discovery of new alleles of sHsp genes in durum wheat (Triticum durum Desf.)

Auteur : Comastri, Alessia

Université de soutenance : Università di Parma .

Grade : Ph.D. in Biotechnologies 2016

Résumé
Plants show high adaptability to the environment also in stress conditions ; study the molecular basis of adaptability in a crop plants as wheat is of particular interest due to its important role as staple food. Moreover climate changes are predicted to have severe negative effects on wheat production over the next decades. Wheat is between the top five cultivated crops in the world and durum wheat (Triticum durum Desf.), in particular, is cultivated in more than 40 countries with a production of about 37 Mtons. The exposure to heat stress during wheat developmental stages negatively affect yield and quality, therefore the current challenge of basic and applied research is to decipher the molecular mechanisms that take place during the adaptation to heat stress to produce new genetic variability to employ in wheat breeding programs. Small heat shock proteins (sHSPs) are chaperone-like proteins that play an important role in the prevention of irreversible aggregation of misfolded protein. The chloroplast sHSPs are known to have an important role in the thermotolerance acquisition protecting the Photosystem II and thylakoid membranes during heat stress. Three complete durum wheat gene sequence coding for chloroplast-localized sHSPs named TdHsp26-A1, TdHsp26-A2, TdHsp26-B1 and a putative pseudogene sequence named TdHsp26-A3, members of the chloroplast sHSP sub-family, have been isolated and characterized. Novel allelic variations in the target genes were detected combining a conventional TILLING approach (HRM detection) with a new online TILLING database search. The search of the TILLING database, based on the exome captured sequencing of the durum wheat cv. Kronos TILLING population, leads to the detection of 36 mutant lines carrying missense mutations spanning the entire coding sequence of TdHsp26-A1, TdHsp26-A2 and TdHsp26-B1 genes. Moreover the conventional HRM screening of 960 genotypes of the durum wheat cv. Cham1 TILLING population leads to the detection of 3 missense mutations within a functional interest region of the TdHsp26-B1. The more interesting SNP mutations inducing non-synonymous substitutions in functional domains of the TdHSP26-A1 and TdHSP26-B1, were confirmed in vivo through the development of specific codominant KASP molecular markers. During this thesis new genetic variability in genes coding for sHSPs has been identified ; this represent a valuable tool for elucidate gene function and to produce new durum wheat varieties with increased adaptation capabilities to heat stress.

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