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Up-regulation of a homeodomain-leucine zipper gene HD-1 contributes to trichome initiation and development in cotton

NIU, Er-li, CAI, Cai-ping, BAO, Jiang-hao, WU, Shuang, ZHAO, Liang, GUO, Wang-zhen
Journal of integrative agriculture 2019 v.18 no.2 pp. 361-371
Gossypium barbadense, Gossypium hirsutum, allotetraploidy, cotton, gene expression regulation, genes, hairs, leaves, loci, phylogeny, retrotransposons, terminal repeat sequences, tissues, trichomes
Plant trichomes originate from epidermal cells. In this work, we demonstrated that a homeodomain-leucine zipper (HD-Zip) gene, Gh_A06G1283 (GhHD-1A), was related to the leaf trichome trait in allotetraploid cotton and could be a candidate gene for the T1 locus. The ortholog of GhHD-1A in the hairless accession Gossypium barbadense cv. Hai7124 was interrupted by a long terminal repeat (LTR) retrotransposon, while GhHD-1A worked well in the hairy accession Gossypium hirsutum acc. T586. Sequence and phylogenetic analysis showed that GhHD-1A belonged to the HD-Zip IV gene family, which mainly regulated epidermis hair development in plants. Silencing of GhHD-1A and its homoeologs GhHD-1D in allotetraploid T586 and Hai7124 could significantly reduce the density of leaf hairs and affect the expression levels of other genes related to leaf trichome formation. Further analysis found that GhHD-1A mainly regulated trichome initiation on the upper epidermal hairs of leaves in cotton, while the up-regulated expression of GhHD-1A in different organs/tissues also altered epidermal trichome development. This study not only helps to unravel the important roles of GhHD-1A in regulating trichome initiation in cotton, but also provides a reference for exploring the different forms of trichome development in plants.