Full-size members of the ABCG (ATP-binding cassette, subfamily G) subfamily of ABC transporters have been found only in plants and fungi. The plant genes encoding full-size ABCGs identified so far appeared to be differentially regulated under various environmental constraints, plant growth regulators, and microbial elicitors, indicating a broad functional role of these proteins in plant responses to abiotic and biotic stress. Nevertheless, the structure and physiological function of full-size ABCGs in many plant species are still unknown. We have recently identified 16 genes encoding full-size ABCG proteins in cucumber and found that the transcripts of two of them, CsABCG36 (CsPDR8) and CsABCG40 (CsPDR12), are most abundant in roots and are significantly affected by phytohormones and auxin herbicide. In this study, we analyzed the structure and phylogeny of all the full-size cucumber ABCG transporters and studied the organ expression profiles of the remaining 14 CsABCG genes. In addition, we investigated the effect of different plant growth regulators and the diterpene sclareolide on CsABCG expression in cucumber roots. Until now, the full-size plant ABCG transporters have been grouped into five different clusters. The new phylogenetic analysis of full-size ABCGs from model plants and cucumber clustered these proteins into six different subgroups. Interestingly, the expression profiles of cucumber ABCG genes assigned to the same clusters were not correlated, suggesting functional diversification or different regulatory mechanisms of the full-size cucumber ABCG proteins.

中文翻译：

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编码黄瓜全尺​​寸 ABCG 蛋白的基因对植物生长调节剂和紫苏内酯表现出不同的反应

仅在植物和真菌中发现了 ABC 转运蛋白的 ABCG（ATP 结合盒，亚家族 G）亚家族的全尺寸成员。迄今为止鉴定出的编码全尺寸 ABCG 的植物基因似乎在各种环境限制、植物生长调节剂和微生物诱导剂下受到差异调节，表明这些蛋白质在植物对非生物和生物胁迫的反应中具有广泛的功能作用。尽管如此，许多植物物种中全尺寸ABCG的结构和生理功能仍然未知。我们最近在黄瓜中鉴定了 16 个编码全尺寸 ABCG 蛋白的基因，发现其中两个的转录本 CsABCG36 (CsPDR8) 和 CsABCG40 (CsPDR12) 在根中含量最高，并且受植物激素和生长素除草剂的显着影响。在这项研究中，我们分析了所有全尺寸黄瓜 ABCG 转运蛋白的结构和系统发育，并研究了其余 14 个 CsABCG 基因的器官表达谱。此外，我们研究了不同植物生长调节剂和二萜紫苏内酯对黄瓜根中 CsABCG 表达的影响。到目前为止，全尺寸植物 ABCG 转运蛋白已分为五个不同的集群。来自模型植物和黄瓜的全尺寸 ABCG 的新系统发育分析将这些蛋白质聚集成六个不同的亚组。有趣的是，分配给相同簇的黄瓜 ABCG 基因的表达谱没有相关性，这表明全尺寸黄瓜 ABCG 蛋白的功能多样化或不同的调节机制。