Design of an optimal promoter involved in the heat‐induced transcriptional pathway in Arabidopsis, soybean, rice and maize. (10th February 2017) - Maruyama, Kyonoshin
Summary: Interactions between heat shock (HS) factors (HSFs) and heat shock response elements (HSEs) are important during the heat shock response (HSR) of flora and fauna. Moreover, plant HSFs that are involved in heat stress are also involved in abiotic stresses such as dehydration and cold as well as development, cell differentiation and proliferation. Because the specific combination of HSFs and HSEs involved in plants under heat stress remains unclear, the mechanism of their interaction has not yet been utilized in molecular breeding of plants for climate change. For the study reported herein, we compared the sequences of HS‐inducible genes and their promoters in Arabidopsis, soybean, rice and maize and then designed an optimal HS‐inducible promoter. Our analyses suggest that, for the four species, the abscisic acid‐independent, HSE/HSF‐dependent transcriptional pathway plays a major role in HS‐inducible gene expression. We found that an 18‐bp sequence that includes the HSE has an important role in the HSR, and that those sequences could be classified as representative of monocotyledons or dicotyledons. With the HS‐inducible promoter designed based on our bioinformatic predictions, we were able to develop an optimal HS‐specific inducible promoter for seedlings or single cells in roots. These findings demonstrate the utility of our HS‐specific inducible promoter, which we expect will contribute to molecular breeding efforts and cell‐targeted gene expression in specific plant tissues. Significance Statement: Several genes are specifically activated in plants in response to high temperatures (heat shock, HS), allowing them to adapt to different environmental conditions. Here, we examined HS‐responsive gene expression in Arabidopsis, soybean, rice, and maize and found that their transcription profiles were highly similar across all four species. We found that conserved sequences, including the HS‐response element in HS‐inducible promoters, are important in HS‐inducible gene expression in the four species, suggesting that they are fundamental to the HS response of land plants. Using these findings, we developed an optimal promoter for Arabidopsis that was specifically induced by HS and therefore has the potential to be used for molecular breeding of plants adapted to climate change.