Cluster compactness is a trait with high agronomic relevance, affecting crop yield and grape composition. Rachis architecture is a major component of cluster compactness determinism, and is a target trait toward the breeding of grapevine varieties less susceptible to pests and diseases. Although its genetic basis is scarcely understood, a preliminary result indicated a possible involvement of the VviUCC1 gene. The aim of this study was to characterize the VviUCC1 gene in grapevine and to test the association between the natural variation observed for a series of rachis architecture traits and the polymorphisms detected in the VviUCC1 sequence. This gene encodes an uclacyanin plant-specific cell-wall protein involved in fiber formation and/or lignification processes. A high nucleotide diversity in the VviUCC1 gene promoter and coding regions was observed, but no critical effects were predicted in the protein domains, indicating a high level of conservation of its function in the cultivated grapevine. After correcting statistical models for genetic stratification and linkage disequilibrium effects, marker-trait association results revealed a series of single nucleotide polymorphisms (SNPs) significantly associated with cluster compactness and rachis traits variation. Two of them (Y-984 and K-88) affected two common cis-transcriptional regulatory elements, suggesting an effect on phenotype via gene expression regulation. This work reinforces the interest of further studies aiming to reveal the functional effect of the detected VviUCC1 variants on grapevine rachis architecture.

中文翻译：

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葡萄藤中 VviUCC1 核苷酸多样性、连锁不平衡及其与轴结构特征的关联


簇紧凑度是一种具有高度农艺相关性的性状，影响作物产量和葡萄组成。轴结构是簇紧凑性决定论的主要组成部分，并且是培育不易受病虫害的葡萄品种的目标性状。尽管其遗传基础尚不清楚，但初步结果表明 VviUCC1 基因可能参与其中。本研究的目的是表征葡萄中的 VviUCC1 基因，并测试观察到的一系列轴结构性状的自然变异与 VviUCC1 序列中检测到的多态性之间的关联。该基因编码参与纤维形成和/或木质化过程的 uclacyanin 植物特异性细胞壁蛋白。在 VviUCC1 基因启动子和编码区中观察到高核苷酸多样性，但在蛋白质结构域中没有预测到关键影响，表明其功能在栽培葡萄树中高度保守。在校正遗传分层和连锁不平衡效应的统计模型后，标记-性状关联结果揭示了一系列与簇紧密度和轴性状变异显着相关的单核苷酸多态性（SNP）。其中两个（Y-984 和 K-88）影响两个常见的顺式转录调控元件，表明通过基因表达调控对表型产生影响。这项工作增强了进一步研究的兴趣，旨在揭示检测到的 VviUCC1 变体对葡萄轴结构的功能影响。