Adventitious rooting in response to long-term cold: a possible mechanism
of clonal growth in alpine perennials
Abstract
Arctic alpine species experience extended periods of cold and
unpredictable conditions during flowering. Thus, often, alpine plants
use both sexual and asexual means of reproduction to maximise fitness
and ensure reproductive success. We used the arctic alpine perennial
Arabis alpina to explore the role of prolonged cold exposure on
adventitious rooting. We exposed plants to 4°C for different durations
and scored the presence of adventitious roots on the main stem and
axillary branches. Our physiological studies demonstrated that the
presence of adventitious roots positively correlates with increased
duration of exposure to cold treatment, with 21 weeks at 4 °C saturating
the effect of cold on adventitious rooting. On the main stem
adventitious roots developed in specific internodes. Transcriptomic and
histological studies indicated that adventitious roots in A.
alpina stems are initiated during cold exposure and emerge after plants
experience growth promoting conditions. The emergence of the
adventitious root primordia correlates with an increase in auxin
response and free endogenous auxin in the stems. Our results highlight
the role of low temperature during clonal growth in alpine plants and
provide insights on the molecular mechanisms involved at different
stages of adventitious rooting.