The diversity in interaction between HsfA2 and ACTIN leads to differences in heat stress responses among different lily varieties

Abstract

Lily is an important cut flower worldwide and prefers cool environments. The high summer temperature in China affects the quality and quantity of cut lily–flower production. In this study, the heat stress transcription factor HsfA2 was cloned from two cultivated commercial varieties, Lilium longiflorum 'White Heaven' and Lilium oriental 'Siberia', which have different responses to heat stress. An actin-interacting protein 3 (AIP3) domain was found in LlHsfA2 of Lilium longiflorum 'White Heaven' but did not appear in LoHsfA2 of Lilium oriental 'Siberia' using prediction from the simple modular architecture research tool (SMART) website. The genes LlACTIN and LoACTIN were cloned, and their amino acid sequences were found to be the same, so they were named LACTIN. There was an interaction between LlHsfA2 and LACTIN, whereas this interaction did not occur between LoHsfA2 and LACTIN based upon the bimolecular fluorescence complementary (BiFC) experiments. The silenced plants of LlHsfA2 and LACTIN were sensitive to heat stress treatment using barley stripe mosaic virus (BSMV) induced gene silencing in 'White Heaven', and LoHsfA2 silenced plants were also sensitive in 'Siberia'. In contrast, LACTIN silenced plants in 'Siberia' were normal. The expressions of LlHsfA2 or LACTIN were reduced in the LACTIN or LlHsfA2 silenced 'White heaven' plants, whereas the expressions of LoHsfA2 or LACTIN were normal in the LACTIN or LoHsfA2 silenced 'Siberia' plants. In conclusion, the diversity of protein interactions between HsfA2 and ACTIN may affect the distinctness of the heat stress response in different lily varieties, which provides new knowledge for further study on the heat stress response in lily.

Keywords

• lily
• heat shock transcription factor
• actin
• heat tolerance