COFFEA SP. SIRNAS: FROM MICROSPOROGENESIS REGULATION TO HEAT STRESS TOLERANCE
microRNAs; phasiRNAs; reproductive development; GABA; anthocyanin; genetic expression regulation; Coffea arabica
siRNAs are small interfering RNAs that regulate post-transcriptional gene expression in several processes in plants, from development to resistance against biotic and abiotic stresses. Faced with the climate change panel we are experiencing, in this work, we investigate the role of these molecules in microsporogenesis and heat stress tolerance in coffee, a commodity of economic importance for Brazil. Here, we were able to identify the presence of reproductive phasiRNAs in coffee anthers at different stages of microsporogenesis. We also characterized the main enzymes of siRNAs biogenesis and triggers for reproductive phasiRNAs in Coffea arabica. We identified new and conserved miRNAs in C. arabica and found 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 heatsensitive coffee plants under heat stress. In addition, we also related a conserved miRNA with anthocyanin production in heat-sensitive coffee plants. Arabidopsis mutants for these miRNAs were developed and subjected to heat stress to prove the role of these molecules in thermal tolerance. Our unprecedented results increase the scientific knowledge about siRNAs in coffee and can help in future genetic improvement programs, and the development of new tools and products.