Coffea sp. siRNAs: from microsporogenesis regulation to warming tolerance

Abstract

SiRNAs are small RNAs that regulate post-transcriptional gene expression in several plant processes, from gamete formation to development, also acting in response to biotic and abiotic stresses. Given the climate changes expected for the coming years, we investigated in this work the role of siRNAs in microsporogenesis and tolerance to temperature increase using species of the genus Coffea as a model of polyploid plants of socioeconomic importance. This thesis was structured as follows: an introduction and theoretical framework (First part) containing the relevant information for understanding the two papers generated (Second part), ending with a general conclusion and future perspectives. In the first paper of this thesis, we reported siRNAs related to the microsporogenesis of C. arabica and molecular pathways related to their biosynthesis. We identified two families of the most important proteins involved in this process, CaAGOs and CaDCLs, in addition to canonical miRNAs and new triggers for 21 and 24 nucleotides reproductive phasiRNAs. We also identified the temporal dynamics of phasiRNAs in the stages of flower bud development in C. arabica microsporogenesis. In the second paper of this thesis, we identified a new miRNA that regulates a GABA transporter, a molecule reported to act in the physiological regulation of plants in the face of heat stress and that has its accumulation reduced in heat-sensitive coffee plants under temperature elevation. In addition, we also related a conserved miRNA with the accumulation of anthocyanin in heat-sensitive coffee plants and the higher tolerance of Arabidopsis mutant plants to heat stress. Finally, with these unprecedented results, we have increased scientific knowledge about siRNAs in coffee plants that are involved in two important biological processes, reproduction and temperature regulation. In this way, we hope to contribute to the development of new tools that help regulate the effects of global warming on crops, such as the development of products based on synthetic miRNAs that regulate molecules of stress physiology, or products that regulate the expression of these miRNAs.