Pigment glands, also known as black glands or gossypol glands, are specific for Gossypium spp. These glands strictly confine large amounts of secondary metabolites to the lysigenous cavity, leading to the glands’ intense colour and providing defence against pests and pathogens. This study performed a comparative transcriptome analysis of glanded versus glandless cotton cultivars. Twenty‐two transcription factors showed expression patterns associated with pigment glands and were characterized. Phenotypic screening of the genes, via virus‐induced gene silencing, showed an apparent disappearance of pigmented glands after the silencing of a pair of homologous MYB‐encoding genes in the A and D genomes (designated as CGP1 ). Further study showed that CGP1a encodes an active transcription factor, which is specifically expressed in the gland structure, while CGP1d encodes a non‐functional protein due to a fragment deletion, which causes premature termination. RNAi‐mediated silencing and CRISPR knockout of CGP1 in glanded cotton cultivars generated a glandless‐like phenotype, similar to the dominant glandless mutant Gl₂^e . Microscopic analysis showed that CGP1 knockout did not affect gland structure or density, but affected gland pigmentation. The levels of gossypol and related terpenoids were significantly decreased in cgp1 mutants, and a number of gossypol biosynthetic genes were strongly down‐regulated. CGP1 is located in the nucleus where it interacts with GoPGF, a critical transcription factor for gland development and gossypol synthesis. Our data suggest that CGP1 and GoPGF form heterodimers to control the synthesis of gossypol and other secondary metabolites in cotton.

中文翻译：

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腺体定位的CGP1控制棉花中的腺体色素沉着和棉酚积累。

色素腺（也称为黑色腺或棉酚腺）是棉属植物的特有色素。这些腺体将大量次生代谢产物严格限制在食源性腔内，导致腺体色泽强烈，并能抵御病虫害和病原体。这项研究对无盖腺和无盖腺棉花品种进行了比较转录组分析。22个转录因子显示了与色素腺相关的表达模式，并进行了表征。通过病毒诱导的基因沉默对基因进行表型筛选，在A和D基因组中的一对同源MYB编码基因（称为CGP1）沉默后，色素腺明显消失。进一步的研究表明CGP1aCGP1d编码一个主动转录因子，在腺体结构中特异性表达，而CGP1d编码由于片段缺失而导致的非功能蛋白，从而导致过早终止。RNAi介导的沉默和棉花敲除品种中CGP1的CRISPR敲除产生了类似腺样无性突变体Gl ₂ ^e 的类腺样表型。显微镜分析表明，CGP1敲除不影响腺体结构或密度，但影响腺体色素沉着。cgp1中的棉酚和相关萜类化合物的水平显着降低突变体和许多棉酚生物合成基因被强烈下调。CGP1位于细胞核中，与GoPGF相互作用，而GoPGF是腺体发育和棉酚合成的关键转录因子。我们的数据表明CGP1和GoPGF形成异二聚体来控制棉酚和棉花中其他次级代谢产物的合成。