As an important horticultural plant, Rhododendron is often used in urban greening and landscape design. However, factors such as the high rate of genetic recombination, frequent outcrossing in the wild, weak linkage disequilibrium, and the susceptibility of gene expression to environmental factors limit further exploration of functional genes related to important horticultural traits, and making the breeding of new varieties require longer time. Therefore, we choose bark as the target trait which is not easily affected by environmental factors, but also has ornamental properties. Genome-wide association study (GWAS) of Rhododendron delavayi (30 samples), Rhododendron irroratum (30 samples) and their F1 generation Rhododendron agastum (200 samples) was conducted on the roughness of bark phenotypes. Finally, we obtained 2416.31 Gbp of clean data and identified 5,328,800 high-quality SNPs. According to the P-value and the degree of linkage disequilibrium of SNPs, we further identified 4 genes out of 11 candidate genes that affect bark roughness. The results of gene differential expression analysis further indicated that the expression levels of Rhdel02G0243600 and Rhdel08G0220700 in different bark phenotypes were significantly different. Our study identified functional genes that influence important horticultural traits of Rhododendron, and illustrated the powerful utility and great potential of GWAS in understanding and exploiting wild germplasm genetic resources of Rhododendron.

中文翻译：

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基因组和 GWAS 分析确定了与杜鹃树皮表型状态显着相关的基因

杜鹃花作为重要的园艺植物，常用于城市绿化和景观设计。然而，遗传重组率高、野外异交频繁、连锁不平衡性弱、基因表达对环境因素的敏感性等因素限制了对重要园艺性状相关功能基因的进一步探索，使得新品种选育面临困难。需要更长的时间。因此，我们选择树皮作为目标性状，既不易受环境因素影响，又具有观赏性。对delavayi杜鹃（30个样本）、irrodendron irroratum（30个样本）及其F1代Rhododendron agastum（200个样本）的树皮表型粗糙度进行了全基因组关联研究（GWAS）。最终，我们获得了2416.31 Gbp的干净数据，并鉴定了5,328,800个高质量的SNP。根据P值和SNP的连锁不平衡程度，我们进一步从11个影响树皮粗糙度的候选基因中鉴定出4个基因。基因差异表达分析结果进一步表明Rhdel02G0243600和Rhdel08G0220700在不同树皮表型中的表达量存在显着差异。我们的研究鉴定了影响杜鹃花重要园艺性状的功能基因，说明了GWAS在了解和开发杜鹃花野生种质遗传资源方面的强大效用和巨大潜力。