Temporally distinct regulatory pathways coordinate thermo-responsive storage organ formation in potato.

Tuberization is an important developmental process in potatoes, but it is highly affected by environmental conditions. Temperature is a major environmental factor affecting tuberization, with high temperatures suppressing tuber development. However, the temporal aspects of thermo-responsive tuberization remain elusive. In this study, we show that FT homolog StSP6A is suppressed by temporally distinct regulatory pathways. Experiments using StSP6A-overexpressing plants show that post-transcriptional regulation plays a major role at the early stage, while transcriptional regulation is an important late-stage factor, suppressing StSP6A at high temperatures in leaves. Overexpression of StSP6A in leaves restores tuber formation but does not recover tuber yield at the late stage, possibly because of suppressed sugar transport at high temperatures. Transcriptome analyses lead to the identification of potential regulators that may be involved in thermo-responsive tuberization at different stages. Our work shows that potato has temporally distinct molecular mechanisms that finely control tuber development at high temperatures.