Hairiness Gene Regulated Multicellular, Non-Glandular Trichome Formation in Pepper Species

Trichomes are unicellular or multicellular epidermal structures that play a defensive role against environmental stresses. Although unicellular trichomes have been extensively studied as a mechanistic model, the genes involved in multicellular trichome formation are not well understood. In this study, we first classified the trichome morphology structures in Capsicum species using 280 diverse peppers. We cloned a key gene (Hairiness) on chromosome 10, which mainly controlled the formation of multicellular non-glandular trichomes (types II, III, and V). Hairiness encodes a Cys2-His2 zinc-finger protein, and virus-induced gene silencing of the gene resulted in a hairless phenotype. Differential expression of Hairiness between the hairiness and hairless lines was due to variations in promoter sequences. Transgenic experiments verified the hypothesis that the promoter of Hairiness in the hairless line had extremely low activity causing a hairless phenotype. Hair controlled the formation of type I glandular trichomes in tomatoes, which was due to nucleotide differences. Taken together, our findings suggest that the regulation of multicellular trichome formation might have similar pathways, but the gene could perform slightly different functions in crops.

Automated summary

Multicellular trichomes in plants are controlled by a key gene called Hairiness, which plays an essential role in regulating the formation of non-glandular trichomes. Differential expression of Hairiness is mainly due to variations in promoter sequences. Transgenic experiments confirmed that low activity of Hairiness promoter leads to a hairless phenotype, indicating a potential pathway for regulating multicellular trichome formation in crops.