Study on the function of TTG1 gene in Camellia oleifera

<i>Camellia oleifera</i> is an economically important woody oil crop in China, where seed oil quality and yield are critical determinants of commercial value. Although the WD40-repeat transcription factor <i>TTG1</i> is known to regulate plant secondary metabolism and development, its specific functions in <i>C. oleifera</i> remain uncharacterized. In this study, we isolated the <i>CoTTG1</i> gene from <i>C. oleifera</i>, which encodes a nuclear-localized protein (molecular weight 38.38 kDa, pI 5.0) sharing 99.71% sequence identity with <i>Camellia japonica TTG1</i>. Heterologous expression resulted in: (1) significantly increased leaf trichome density (up to 114 trichomes/50 mm²); (2) enhanced seed anthocyanin accumulation (199-318% increase); and (3) substantial alterations in fatty acid composition, including 79% elevation in oleic acid (C18:1), 113% increase in gondoic acid (C20:1), 35% reduction in both linolenic (C18:3) and palmitic acids (C16:0), and 87% decrease in erucic acid (C22:1). Molecular analyses revealed that <i>CoTTG1</i> mediates these phenotypic changes through upregulation of trichome development-related genes (<i>AtETC1</i>, <i>AtGL1</i>, <i>AtCPC</i>), anthocyanin biosynthesis genes (<i>AtF3'H</i>, <i>AtLDOX</i>, <i>AtUFGT</i>), and lipid metabolism genes (<i>AtLACS8</i>, <i>AtSAD</i>). These findings demonstrate the pleiotropic regulatory roles of <i>CoTTG1</i> in controlling key agronomic traits, establishing it as a valuable molecular target for genetic improvement of <i>C. oleifera</i>.