Investigation of plant genetic-microbiome interactions in different plant species

The rhizosphere, i.e. the soil surrounding the plant roots, and endosphere, i.e. the microbial communities within the plant organs harbors microbes known to influence root and plant physiological processes. An important question is to what extent plant species, genotypes and environmental conditions affect bacterial and fungal communities. The objectives of the first research study were to unravel and compare the rhizospheric microbiota of grape in two independent vineyards using 16S and ITS amplicon sequencing, evaluate location and varietal effects, and test the correlation between bioavailable copper levels and other soil parameters with microbiota composition and diversity. Our results showed that the microbial alpha diversity based on Shannon index differed significantly between vineyards while it did not differ between two grape cultivars. In the second study, we were focusing on different wheat species and genotypes such as Bread Wheat, Wild Emmer Wheat, Domesticated Emmer Wheat, Durum Wheat Landraces, Durum Wheat cultivars, T. monococcum and triticale in two fields located in Bologna and Foggia. The objectives of this research experiment were to elucidate and compare the rhizospheric and endophytic microbiota of 30 diverse wheat genotypes in two different fields using 16S amplicon sequencing. Our results showed that the microbial alpha diversity based on Shannon index differed significantly between fields of Bologna and Foggia, in which Bologna had a higher diversity in respect to Foggia for both rhizospheric and endophytic communities. Using Shannon index there was significant differences, for instance, between Durum Emmer Wheat and Wild Emmer Wheat in Bologna, and between Bread Wheat and Durum Wheat Landraces in Foggia. Our results contribute to understand the role of wheat species and genotype and the filed management on the root-microbe-soil interactions in the perspective of understanding their impact on crop systems sustainability.

Characterization of an international tetraploid wheat germplasm including landraces and primitive wheat towards improved resilience to abiotic and biotic stresses and quality

This thesis aimed to characterise two large tetraploid germplasm collections. The Global Durum Panel, involving modern cultivars and landrances and the Tetraploid Global Collection which comprises all the tetraploid wheat subgroups. Two distinct parallel studies were carried out. The first is focused on the characterisation of both collection for yield and quality related traits. The panel were phenotyped for two consecutive years each. In this phase the following traits were collected: the number of fertile spikelets per spike, the number of fertile florets of central spikelet for the spike-related traits. The following grain related traits were also phenotyped: the thousand kernel weight, the average grain area, average grain length, average grain width, grain brightness, grain redness, grain yellowness. GWAS analysis were performed for each collected trait and major QTLs were subjected to candidate gene analysis. Major QTLs emerging from GWA study were located on chromosome 2A with a strong bibliographic evidence for grain number-related traits such as the fertile spikelet number, the number of fertile florets per central spikelet. On the other hand two evident peaks were detected on chromosomes 6A and 7B for grain size and weight related traits. The second work was focused on the characterisation of the Global Durum Panel for root system architecture components, namely the root growth angle. GWAS analysis was perfomed and three major QTLs were detected on chromosome 2A, 6A and 7A. These three QTLs all have a bibliographic evidence.