Dissecting transcriptional responses of nucleolin mutants to red light stimulation and darkness in ground reference conditions

Understanding plant adaptive responses to the space environment is a requisite for enabling space farming. Spaceflight produce deleterious effects on plant cells, particularly affecting ribosome biogenesis, a complex stress-sensitive process coordinated with cell division and differentiation, known to be activated by red light. Here, we have used mutants from the two nucleolin genes in Arabidopsis (NUC1 and NUC2), encoding the main regulator of the ribosome biogenesis in the nucleolus, in order to better understand their role in adaptive response mechanisms to stress. Thus, we show that nucleolin stress-related gene NUC2 can compensate the environmental stress provided by darkness in nuc1 plants, while nuc2 plants are not able to provide a complete response to red light. These ground control findings, as part of the ESA/NASA Seedling Growth spaceflight experiments will determine the basis for the identification of a genetic background enabling an adaptive advantage for plants in future space experiments.