DYNAMICS OF THE BRASSINOSTEROID TRANSCRIPTION FACTOR BES1 IN PLANT RESPONSES TO TEMPERATURE CUES

MORA GARCIA, SANTIAGO; COSTIGLIOLO ROJAS, CECILIA; BIANCHIMANO, LUCIANA; CASAL, JORGE J.

Entre Rios

Congreso; LIV Reunion Anual SAIB; 2018

SAIB

Plant growth is coordinately regulated by environmental and hormonal signals, including a preeminent growth of brassinosteroids (BR). In thiswork we studied temperature effects on the dynamics of the BES1 transcription factor a key component of the signaling pathway downstream BRperception. In Arabidopsis thaliana seedlings, the promotion of hypocotyl growth induced by warm temperature (29ºC) compared to controlconditions (20ºC) is enhanced in the bes1-1D gain-of-function mutant, compared to the wild type. The de-phosphorylated form of BES1 isconsidered to be active in the control of gene expression. We used plants bearing the pBES1:BES-GFP transgene and measured nuclearfluorescence levels by confocal microscopy. The plants exposed to high temperature showed increased nuclear protein in the hypocotyl anddecrease levels in the cotyledons. We also measured BES1 gene expression, by qRT-PCR, independently in the hypocotyl and in the cotyledons.We observed a deduction in expression levels in response to warm temperature, particularly in the cotyledons. We conclude that a differentialbalance of the transcriptional and posttranscriptional control of BES1 by temperature leads to opposite responses in the hypocotyl andcotyledons, which in turn correlate with the growth response.