Studio del ruolo di un mitovirus nelle piante di quinoa (Chenopodium quinoa Willd.).

Climate change is a growing threat to biodiversity, as it endangers both natural and agricultural ecosystems. The preservation and promotion of crop biodiversity, along with the crop associated biodiversity, play a pivotal role in ensuring food security and sustainability. Chenopodium quinoa, due to its remarkable stress tolerance and nutritional composition comparable to major crops such as rice and maize, is increasingly attracting attention worldwide. This interest reflects its potential as a valuable crop, especially for cultivation in diverse agroecological systems. Furthermore, alongside the stress-tolerant nature of quinoa, recent studies discovered a mitovirus (CqMV1) infecting quinoa genotype. Mitoviruses are a genus of the Mitoviridae family, positive single-stranded RNA viruses that replicate and remain within the mitochondria of their host cells. Notably, CqMV1 presence in quinoa plants could potentially enhance plants performance under drought conditions. Previous studies showed that CqMV1 can be transmitted vertically, through genotypes breeding, and it was confirmed in the F1 lines RegxBo78 and RegxBo25 generated by crossing Regalona (Reg, CqMV1 infected line) with Bo25 and Bo78 (not-infected) genotypes. This thesis aimed to investigate the role of the mitovirus CqMV1 associated with genotypes of quinoa plants. In order to evaluate the specific contribution of CqMV1 in quinoa plants, the drought-induced responses of F1 genotypes (RegxBo78, Bo78xReg; RegxBo25) generated by crossing the parental lines (Regalona, Bo25 and Bo78) were monitored. Leaf samplings were collected during the drought period and during recovery. Initially, the quantification of some parameters associated with drought-induced response were conducted using two distinct methodologies, such as the quantification of isotopic variation of carbon (C) and nitrogen (N) and evaluation of anion content through capillary electrophoresis. Since the infection of CqMV1 in quinoa genotypes has been related with alterations of the gene expression of eight putative proteins, which are involved in metabolism and stress-induced response of plants, the possible direct role of CqMV1 in the transcriptional regulation of genes encoding for such marker proteins has been carried out on the F1 genotypes. Results showed that five of such genes, including those encoding for Ornithine-delta-aminotransferase (DELTA-OAT), 2-oxoacid dehydrogenases acyltransferase family protein (BCE2), Electron transfer flavoprotein alpha (ETFALPHA), 3- methylcrotonyl-CoA carboxylase (MCCB) and Serine transhydroxymethyltransferase 1 (SHM1) displayed similar transcriptional regulation under drought in RegxBo25 and Reg genotypes. Such results suggest that Regalona maternal genome, and likely CqMV1, affect the expression of such genes, resulting, in turn, with a specific modulation of drought-induced responses. Overall, our results suggest that isogenic lines comparison represent a useful tool to discriminate the role of this mitovirus. However, our results indicate that RegxBo25 displayed higher percentage of CqMV1 infection in F1, suggesting that crossing Reg x Bo25 should be considered for future investigation. This work provides new insights on the possible impact of mitovirus on plant metabolism under stress.