The main aim of this work was to better understand how the low temperature signal
from the leaves may affect the stress responses in the roots, and how the light conditions
modify certain stress acclimation processes in rice plants. Rice plants grown at 27°C
were exposed to low temperatures (12°C) with different light intensities, and in the
case of some groups of plants, only the leaves received the cold, while the roots
remained at control temperature. RNA sequencing focusing on the roots of plants grown
under normal growth light conditions found 525 differentially expressed genes in different
comparisons. Exposure to low temperature led to more down-regulated than up-regulated
genes. Comparison between roots of the leaf-stressed plants and whole cold-treated
or control plants revealed that nitrogen metabolism and nitric oxide-related signalling,
as well as the phenylpropanoid-related processes, were specifically affected. Real-time
PCR results focusing on the COLD1 and polyamine oxidase genes, as well as metabolomics
targeting hormonal changes and phenolic compounds also showed that not only cold exposure
of the leaves, either alone or together with the roots, but also the light conditions
may influence certain stress responses in the roots of rice plants.