2.5 The abundance of dephosphorylated BES1 is responsible for
BR-enhanced thermomemory
To elucidate the critical function of BES1 accumulated during thermal
memory phase for BR signal, we detected BES1 protein by immunoblot
analysis in det2 and BES1-RNAi seedlings at 48 h of memory
phase. As shown in Supplementary Fig. 2, the abundance of
dephosphorylated BES1 was higher in det2 , whereas it was almost
undetectable in BES1-RNAi . This finding provides further evidence
for BES1 involved in the regulation of thermomemory, increased BES1
level in det2 could explain the enhanced thermotolerance indet2 mutant (Supplementary Fig. 1) and a lack of BES1 could be
responsible for the thermomemory function-loss in BES1-RNAi (Fig.
2).
We next subjected 5-day-old bes1-D mutant and Col-0 seedlings to
our priming and triggering stimulus protocol, since the amino acid
mutation in bes1-D results in an increase in the total amount of
BES1 protein. Not surprisingly, dephosphorylated BES1 in bes1-Dis comparably more abundant than that of Col-0 during the whole memory
phase. Consistent with this observation, bes1-D seedlings
revealed better thermotolerance than Col-0 in both unprimed and primed
conditions, as the survival rate was comparably higher than Col-0 (Fig.
4C), accompanied with lower electrolyte leakage in bes1-D (Fig.
4D), underscoring the contribution of bio activated BES1 to elevating
the thermolerance and enhance thermomemory.