Abstract
Recent studies have revealed that a mild increase in environmental temperature stimulates the growth of Arabidopsis seedlings by promoting biosynthesis of the plant hormone auxin. However, little is known about the role of other factors in this process. In this report, we show that increased temperature promotes rapid accumulation of the TIR1 auxin co-receptor, an effect that is dependent on the molecular chaperone HSP90. In addition, we show that HSP90 and the co-chaperone SGT1 each interact with TIR1, confirming that TIR1 is an HSP90 client. Inhibition of HSP90 activity results in degradation of TIR1 and interestingly, defects in a range of auxin-mediated growth processes at lower as well as higher temperatures. Our results indicate that HSP90 and SGT1 integrate temperature and auxin signalling in order to regulate plant growth in a changing environment.
Highlights
Recent studies have revealed that a mild increase in environmental temperature stimulates the growth of Arabidopsis seedlings by promoting biosynthesis of the plant hormone auxin
And regulation of SCF complexes such as SCFTIR1 is a highly dynamic process that involves a number of proteins and protein complexes including the ubiquitin-like protein Nedd[8] (RELATED TO UBIQUITIN in Arabidopsis), the COP9 signalosome (CSN) complex, and the cullin-associated Nedd8-disassociated (CAND1) protein[16,17,18,19,20,21]
We show that the HSP90-SGT1 chaperone system is required for the plants’ response to an increase in ambient temperature
Summary
Recent studies have revealed that a mild increase in environmental temperature stimulates the growth of Arabidopsis seedlings by promoting biosynthesis of the plant hormone auxin. Recent studies indicate that the transcription factor phytochromeinteracting factor 4 (PIF4) and the versatile plant hormone auxin play pivotal roles in ambient temperature-regulated hypocotyl growth in Arabidopsis[7,8]. The RUB1, CSN and CAND1 have all been implicated in SCFTIR1/AFB function[19,22,23,24] In addition to these factors, genetic studies show that a protein called SUPPRESSOR OF G2 ALLELE SKP1 (SGT1) is required for auxin response[25]. SGT1 and HSP90 play critical roles in regulating abiotic and biotic stress responses[2,4] They are required for normal function of nucleotide-binding domain leucine-rich repeat (NLR) immune sensor proteins in both plants and animals[28,29]. Their role in ambient temperature sensing and signalling has not been investigated
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