Abstract
High temperature is one of key stress factors with negative impacts on the growth of plants and the productivity of crops. Previously, we have reported that DREB2A activates expression of many stress-responsive-genes involved in heat stress tolerance and that HsfA3 is the most up-regulated gene in the transgenic Arabidopsis plants overexpressing DREB2A.
In this study, we carried out expression and transactivation analyses of HsfA3 and demonstrated that expression of the HsfA3 gene is directly regulated by DREB2A under the heat stress condition. We also characterized the function of HsfA3 using HsfA3 overexpressors and knockout mutants and found that HsfA3 regulates many heat shock-related genes in response to heat stress. Furthermore, we found that thermotolerance of the HsfA3 overexpressors was increased and that of the mutants was decreased. We will discuss the role of HsfA3 in the transcriptional cascades in response to heat stress.
