Morpho-physiological characterization and whole genome transcript profiling of rice genotypes that belongs to sub-species Indica, Japonica and wild relatives were carried out under salt stress. The existence of qualitatively different mechanisms of salt tolerance across the genotypes was identified. Multivariate analysis was applied to categorize the genotypes according to their level of tolerance. Modified SAM analysis elucidated the trait specific expression of genome wide transcripts. Gene ontology enrichment analysis identified the genes involved in different molecular functions such as signal transduction, transcription factor and ion homeostasis etc. Gene network analysis identified the regulatory network of genes that are active in different tissues. The differential expression of transcripts of four tolerant and two susceptible Indica genotypes under stress were further analysed. The candidate genes for different biological processes and molecular functions are identified and discussed. Highly induced stimulus responsive gene Os01g0159600 (OsLEA1a) and Os05g0382200 (Nhx) can be mentioned for instance. The differentially expressed genes that are located within the salt stress related QTLs were also identified. The transcriptomics data were also used to predict the salinity tolerance of genotypes using OSC-PLSDA model. The combined physiological and transcriptomic approach of this study gives a complementary whole organism assessment of plants responses to salt stress.

Agrobiodiversity are threatened due to habitat loss, land reclamation and fragmentation, spread of diseases and pests, genetic uniformity, genetic erosion, and other human activities. Crop wild relatives (CWR) are wild species that are more or less genetically related to crops that can be used to introgress useful genes for improvement of productivity, resistance to biotic and abiotic stresses and quality of cultivated crop. These valuable resources are threatened and untapped for crop improvements. Therefore, their conservation would be valuable and will contribute to maintaining and promoting the sustainability of crop diversity, facilitating agricultural production and supporting the increasing demand for food, feed and natural resources. This thesis tackle for the first time the diversity and conservation status of CWR in North Africa region. In order to achieve this goal, different methods, approaches and techniques were used. These are identifying CWR in the region (CWR checklist), prioritize the checklist, ex situ and in situ gap analyses, species distribution modelling, threat assessment using IUCN Red List categories, climate change assessment and molecular genetic analysis of wild barley (Hordeum vulgare subsp. spontaneum (C. Koch) Thell). The outcomes will assist in lay the foundations for future ex situ and in situ conservation, and subsequent use.

There are some contradictory theories on how tolerant honey bees are of pesticides. Since the honey bee genome has been published (Honey bee Genome Sequencing Consortium, 2006), more is known about their metabolic systems, especially the detoxification pathways for potential xenobiotics. Bioassay and biochemical data from various studies have shown that both P450s and carboxylesterases are responsible for pesticide metabolism in honey bees. Here, those metabolic enzymes that confer primary defence to different classes of insecticides in honey bee were validated. Metabolic enzymes are characterised regarding their ability to interact with the insecticide. Synergist bioassay results with PBO and EN 16/5-1 suggest that detoxification mechanism(s) play an important role in protecting honey bees from selected insecticide toxicity. No binding was found between honey bee esterases and tested insecticides, whilst inhibition of P450 activity sensitised the honey bees to these chemicals. Metabolism of tau-fluvalinate and thiacloprid in honey bees is reportedly due to P450 activity, but this metabolism may not be the only reason for the relatively benign action of this insecticide on bees. Honey bees are less sensitive to neonicotinoids containing a cyanoimino pharmacophore than to those with a nitroimino group, however the specific enzymes involved in detoxification remain to be characterised. In this work, pre-treatment of honey bees with a sub-lethal dose of an insecticide induced protection to the same compound. Transcriptome profiling, using microarrays, identified a number of genes encoding detoxification enzymes that were overexpressed significantly in insecticide-treated bees compared to untreated controls.