Has ATP-dependent RNA helicase activity in vitro. Acts as a thermosensitive RNA chaperone required for normal processing of pre-rRNA intermediates. Required for normal cell division at high temperatures. Required for a primary metabolism adaptation to high temperatures to support thermotolerant growth by regulating gene expression. Partially rescues the yeast rRNA helicase RRP3 mutant which has repressed cell proliferation at 38 degrees Celsius. ATP + H2O = ADP + H(+) + phosphate Helicase activity is activated by temperature increase. Interacts with U3 small nucleolar RNA (U3 snoRNA) as part of the ribosomal small subunit (SSU) processome. Localization is not affected by temperature. Widely expressed in roots, shoots, leaves, culms, spikelets and anthers during different developing stages. By high temperature and the circadian clock. Expression peaks at zeitgeber time 9 (ZT9) corresponding to afternoon of a subjective day, the hottest time of daily temperature fluctuation. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Thermosensitive dwarf mutant. Reduced plant height, root length and crown root number at 30, 32.5 and 35 degrees Celsius, whereas they grow similarly to wild-type at 25 degrees Celsius except for a slightly reduced plant height. At tillering stage, plants grown in a hot climate show narrowed leaf blades mainly due to a decrease in vascular bundle and lateral vein numbers, and all internodes are shortened. Furthermore, cross-sections of leaf sheath, leaf blades, internodes and root maturation zones do not show a significant difference in cell elongation, but a reduction in cell numbers compared to wild-type. Belongs to the DEAD box helicase family. DDX47/RRP3 subfamily.