HISTONE DEACETYLASE 19 interacts with ELONGATED HYPOCOTYL5 to regulate wheat cuticular wax biosynthesis in response to ultraviolet B radiation

SUMMARY Ultraviolet B (UV‐B) radiation negatively affects crop production and threatens food security. The waxy cuticle coats the above‐ground organs of terrestrial plants and contributes to plant adaptation to UV‐B radiation. However, the molecular mechanism underlying the response of plant cuticular wax biosynthesis to UV‐B radiation remains poorly understood. Here, we show that 3‐ketoacyl‐CoA synthase 2s (TaKCS2s) are required for cuticular wax biosynthesis in bread wheat ( Triticum aestivum ) and that their expression is activated by transcription factor MYELOBLASTOSIS30 (TaMYB30). We established TaMYB30 genes as direct targets of transcription factor ELONGATED HYPOCOTYL5 (TaHY5), which interacts with HISTONE DEACETYLASE 19 (TaHDA19). Furthermore, we demonstrated that TaHDA19 negatively regulates the expression of TaMYB30 genes by mediating histone deacetylation and reducing TaHY5 enrichment at TaMYB30 promoter regions, thereby contributing to the suppression of wheat cuticular wax biosynthesis. Finally, we revealed that the suppression of TaHDA19 on TaMYB30 transcription was abrogated by the UV RESISTANCE LOCUS 8 (TaUVR8)‐mediated induction of TaHY5 under UV‐B radiation, resulting in increased wheat cuticular wax biosynthesis. These data collectively support the hypothesis that a histone deacetylase fine‐tunes the response of wheat wax biosynthesis to UV‐B radiation via interplay with the transcription factor ELONGATED HYPOCOTYL5.