A lily heat-inducible multi-protein bridging factor, LlMBF1c, plays a crucial role in plant thermotolerance

Abstract Lily ( Lilium spp.) is popular for its colorful flowers and exquisite scents. Nonetheless, high temperatures often severely reduce its yield production and quality. The implementation of biotechnological approaches to manipulate the expression of key heat-resistant genes is an effective way to improve the thermotolerance of plants. Here, we isolated a gene encoding for a multi-protein bridging factor 1c (MBF1c) from L. longiflorum 'White Heaven' ( LlMBF1c ), which was highly similar to MBF1c from Elaeis guineensis ( EgMBF1c ). LlMBF1c harbors conserved MBF1 and helix-turn-helix (HTH) domains. Moreover, the expression of LlMBF1c and its promoter activity were enhanced under high-temperature conditions. Further analysis indicated that LlMBF1c is a transcriptional repressor in both yeast and Nicotiana benthamiana . Its protein was located in the nucleus and cytoplasm of N. benthamiana leaf cells. Overexpression of LlMBF1c in lily and Arabidopsis resulted in enhanced thermotolerance in these plants. By contrast, silencing LlMBF1c reduced the thermotolerance of lily. Our results identified an important candidate gene that can be utilized to develop thermotolerant lily germplasm.