Fruit colour is one of the most important commercial traits of pepper (Capsicum spp.), a major horticultural crop worldwide. Some pepper accessions temporarily accumulate anthocyanins during fruit development and gradually lose them upon fruit ripening. Meanwhile, anthocyanin biosynthesis gradually stops. However, how this process is exactly regulated is still largely unknown. R2R3-MYB is one of the largest plant transcription factor families, and it is considered the most important regulator for the biosynthesis of anthocyanins and other flavonoids. Although R2R3-MYBs are widely studied in many plants, research in pepper has been limited. In this study, we performed a genome-wide analysis of R2R3-MYBs across three cultivated pepper species (C. annuum, C. baccatum, and C. chinense ) involving identification, chromosome localization, gene structure analysis, phylogenetic analysis and collinearity analysis. Candidate R2R3-MYB repressors were further identified based on repression motifs. An R2R3-MYB gene, CaMYB101, was selected based on its high homology with anthocyanin biosynthesis repressors in tomato and petunia as well as its high expression level in fruit when purple pigmentation started to discolour. By using virus-induced gene silencing, CaMYB101 was characterized as an anthocyanin biosynthesis repressor. To our knowledge, CaMYB101 is the first transcriptional repressor associated with anthocyanin biosynthesis identified in pepper.

中文翻译：

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辣椒（辣椒属）中 R2R3-MYB 转录因子的全基因组表征揭示了 CaMYB101 作为抑制因子在花青素生物合成中的作用

果实颜色是辣椒（辣椒属）最重要的商业特征之一，辣椒是世界上主要的园艺作物。一些辣椒种质在果实发育过程中会暂时积累花青素，并在果实成熟时逐渐失去花青素。同时，花青素的生物合成逐渐停止。然而，这个过程是如何被精确调节的，在很大程度上仍然是未知的。R2R3-MYB 是最大的植物转录因子家族之一，被认为是花青素和其他类黄酮生物合成最重要的调节因子。尽管 R2R3-MYBs 在许多植物中得到了广泛的研究，但对辣椒的研究却很有限。在这项研究中，我们对三种栽培辣椒（C. annuum、C. baccatum ）的 R2R3-MYB 进行了全基因组分析, 和C. chinense ) 涉及鉴定、染色体定位、基因结构分析、系统发育分析和共线性分析。基于抑制基序进一步鉴定了候选 R2R3-MYB 抑制因子。选择 R2R3-MYB 基因CaMYB101是基于其与番茄和矮牵牛中的花青素生物合成抑制因子的高度同源性以及当紫色色素沉着开始变色时在果实中的高表达水平。通过使用病毒诱导的基因沉默，CaMYB101 被表征为花青素生物合成阻遏物。据我们所知，CaMYB101 是第一个与胡椒中鉴定的花青素生物合成相关的转录抑制因子。