The cotton genus comprises both diploid and allotetraploid species, and the diversity in petal colour within this genus offers valuable targets for studying orthologous gene function differentiation and evolution. However, the genetic basis for this diversity in petal colour remains largely unknown. The red petal colour primarily comes from C, G, K, and D genome species, and it is likely that the common ancestor of cotton had red petals. Here, by employing a clone mapping strategy, we mapped the red petal trait to a specific region on chromosome A07 in upland cotton. Genomic comparisons and phylogenetic analyses revealed that the red petal phenotype introgressed from G. bickii. Transcriptome analysis indicated that GhRPRS1, which encodes a glutathione S-transferase, was the causative gene for the red petal colour. Knocking out GhRPRS1 resulted in white petals and the absence of red spots, while overexpression of both genotypes of GhRPRS1 led to red petals. Further analysis suggested that GhRPRS1 played a role in transporting pelargonidin-3-O-glucoside and cyanidin-3-O-glucoside. Promoter activity analysis indicated that variations in the promoter, but not in the gene body of GhRPRS1, have led to different petal colours within the genus. Our findings provide new insights into orthologous gene evolution as well as new strategies for modifying promoters in cotton breeding.

中文翻译：

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GhRPRS1 顺式元素的自然变化导致棉花花瓣颜色的多样性


棉花属包括二倍体和异体四倍体物种，该属内花瓣颜色的多样性为研究直系同源基因功能分化和进化提供了有价值的靶标。然而，这种花瓣颜色多样性的遗传基础在很大程度上仍然未知。红色花瓣颜色主要来自 C、G、K 和 D 基因组物种，棉花的共同祖先很可能是红色花瓣。在这里，通过采用克隆定位策略，我们将红色花瓣性状定位到陆地棉染色体 A07 上的特定区域。基因组比较和系统发育分析显示，红色花瓣表型来自 G. bickii。转录组分析表明，编码谷胱甘肽 S-转移酶的 GhRPRS1 是红色花瓣颜色的致病基因。敲除 GhRPRS1 导致花瓣白色且没有红点，而 GhRPRS1 的两种基因型的过表达导致花瓣呈红色。进一步分析表明，GhRPRS1 在转运天竺葵素-3-O-葡萄糖苷和矢车菊素-3-O-葡萄糖苷中发挥作用。启动子活性分析表明，GhRPRS1 启动子的变异，而不是 GhRPRS1 基因体的变异，导致该属内的花瓣颜色不同。我们的研究结果为直系同源基因进化提供了新的见解，并为棉花育种中修饰启动子提供了新策略。