BACKGROUND Domain of unknown function (DUF) proteins represent a number of gene families that encode functionally uncharacterized proteins in eukaryotes. The DUF4228 gene family is one of these families in plants that has not been described previously. RESULTS In this study, we performed an extensive comparative analysis of DUF4228 proteins and determined their phylogeny in the plant lineage. A total of 489 high-confidence DUF4228 family members were identified from 14 land plant species, which sub-divided into three distinct phylogenetic groups: group I, group II and group III. A highly conserved DUF4228 domain and motif distribution existed in each group, implying their functional conservation. To reveal the possible biological functions of these DUF4228 genes, 25 ATDUF4228 sequences from Arabidopsis thaliana were selected for further analysis of characteristics such as their chromosomal position, gene duplications and gene structures. Ka/Ks analysis identified seven segmental duplication events, while no tandemly duplication gene pairs were found in A. thaliana. Some cis-elements responding to abiotic stress and phytohormones were identified in the upstream sequences of the ATDUF4228 genes. Expression profiling of the ATDUF4228 genes under abiotic stresses (mainly osmotic, salt and cold) and protein-protein interaction prediction suggested that some ATDUF4228 genes are may be involved in the pathways of plant resistance to abiotic stresses. CONCLUSION These results expand our knowledge of the evolution of the DUF4228 gene family in plants and will contribute to the elucidation of the biological functions of DUF4228 genes in the future.

中文翻译：

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陆地植物DUF4228基因家族的全面基因组分析和非生物胁迫下ATDFF4228的表达谱。

背景技术未知功能（DUF）蛋白的结构域代表编码真核生物中功能上未表征的蛋白的许多基因家族。DUF4228基因家族是植物中这些家族之一，以前没有描述过。结果在这项研究中，我们对DUF4228蛋白进行了广泛的比较分析，并确定了它们在植物谱系中的系统发育。从14种陆地植物物种中总共鉴定出489个高可信度DUF4228家族成员，这些物种又细分为三个不同的系统发育组：第一组，第二组和第三组。每个组中都存在高度保守的DUF4228域和基序分布，这表明它们具有功能保守性。为了揭示这些DUF4228基因的可能生物学功能，选择拟南芥的25个ATDFF4228序列用于特征的进一步分析，例如它们的染色体位置，基因重复和基因结构。Ka / Ks分析确定了七个节段性复制事件，而在拟南芥中未发现串联复制基因对。在ATDUF4228基因的上游序列中鉴定出一些响应非生物胁迫和植物激素的顺式元素。ATDUF4228基因在非生物胁迫（主要是渗透，盐和寒冷）下的表达谱分析和蛋白质-蛋白质相互作用预测表明，某些ATDUF4228基因可能参与植物对非生物胁迫的抗性途径。