Morphological and transcriptomic responses/acclimations of erect-type submerged macrophyte Hydrilla verticillata both at low-light exposure and light recovery phases

Light intensity is a determinant for submerged macrophytes. Little is known about their molecular responses to low-light exposure, despite being more informative and responsive than morphological traits. For erect-type submerged macrophytes, the stem is more crucial relative to the leaf in acclimation to low-light stress, but receives less attention. We determined morphological and stem transcriptomic responses/acclimations of Hydrilla verticillata to extremely and mildly low light (7.2 and 36 μmol photons m–2 s–1, respectively), i.e. EL and ML, with the radiation intensity of 180 μmol photons m–2 s–1 as the control. Low-light exposure continued for nine days, followed by a seven-day recovery phase (180 μmol photons m–2 s–1). At the exposure phase, the low-light treatments, in particular the EL, decreased relative growth ratio, but induced greater height and longer stem internode distance and epidermal cell. Such responses/acclimations continued into the recovery phase, despite more or ...