Cannabis sativa is increasingly being grown around the world for medicinal, industrial, and recreational purposes. As in all cultivated plants, cannabis is exposed to a wide range of pathogens, including powdery mildew (PM). This fungal disease stresses cannabis plants and reduces flower bud quality, resulting in significant economic losses for licensed producers. The Mildew Locus O (MLO) gene family encodes plant-specific proteins distributed among conserved clades, of which clades IV and V are known to be involved in susceptibility to PM in monocots and dicots, respectively. In several studies, the inactivation of those genes resulted in durable resistance to the disease. In this study, we identified and characterized the MLO gene family members in five different cannabis genomes. Fifteen Cannabis sativa MLO (CsMLO) genes were manually curated in cannabis, with numbers varying between 14, 17, 19, 18, and 18 for CBDRx, Jamaican Lion female, Jamaican Lion male, Purple Kush, and Finola, respectively (when considering paralogs and incomplete genes). Further analysis of the CsMLO genes and their deduced protein sequences revealed that many characteristics of the gene family, such as the presence of seven transmembrane domains, the MLO functional domain, and particular amino acid positions, were present and well conserved. Phylogenetic analysis of the MLO protein sequences from all five cannabis genomes and other plant species indicated seven distinct clades (I through VII), as reported in other crops. Expression analysis revealed that the CsMLOs from clade V, CsMLO1 and CsMLO4, were significantly upregulated following Golovinomyces ambrosiae infection, providing preliminary evidence that they could be involved in PM susceptibility. Finally, the examination of variation within CsMLO1 and CsMLO4 in 32 cannabis cultivars revealed several amino acid changes, which could affect their function. Altogether, cannabis MLO genes were identified and characterized, among which candidates potentially involved in PM susceptibility were noted. The results of this study will lay the foundation for further investigations, such as the functional characterization of clade V MLOs as well as the potential impact of the amino acid changes reported. Those will be useful for breeding purposes in order to develop resistant cultivars.

大麻越来越多地在世界各地种植用于医药、工业和娱乐目的。与所有栽培植物一样，大麻暴露于多种病原体，包括白粉病 (PM)。这种真菌病会给大麻植物造成压力并降低花芽质量，从而给获得许可的生产商造成重大经济损失。这霉变位点O (MLO) 基因家族编码分布在保守进化枝中的植物特异性蛋白质，其中进化枝 IV 和 V 分别与单子叶植物和双子叶植物的 PM 易感性有关。在几项研究中，这些基因的失活导致对该疾病的持久抵抗。在这项研究中，我们确定并表征了MLO五种不同大麻基因组中的基因家族成员。十五大麻苜蓿 MLO (CsMLO) 基因是在大麻中手动策划的，CBDRx、牙买加狮子女性、牙买加狮子男性、紫库什和 Finola 的数量分别在 14、17、19、18 和 18 之间变化（考虑旁系同源基因和不完整基因时）。进一步分析CsMLO基因及其推断的蛋白质序列揭示了该基因家族的许多特征，例如存在七个跨膜结构域、MLO 功能结构域和特定的氨基酸位置，并且存在且高度保守。来自所有五个大麻基因组和其他植物物种的 MLO 蛋白质序列的系统发育分析表明，如其他作物中所报道的那样，存在七个不同的进化枝（I 到 VII）。表达分析表明CsMLO 来自进化枝 V， CsMLO1 和 CsMLO4, 在以下情况下显着上调 鹿茸菌感染，提供初步证据表明它们可能与 PM 易感性有关。最后，检查内部变异CsMLO1 和 CsMLO4在 32 个大麻品种中发现了几种氨基酸变化，这可能会影响它们的功能。总之，大麻MLO基因被鉴定和表征，其中可能涉及 PM 易感性的候选基因被指出。这项研究的结果将为进一步研究奠定基础，例如进化枝 V MLO 的功能表征以及报告的氨基酸变化的潜在影响。这些将用于育种目的，以开发抗性栽培品种。