Plant non-specific lipid transfer proteins (nsLTPs), a group of small, basic ubiquitous proteins to participate in lipid transfer, cuticle formation and stress response, are involved in the regulation of plant growth and development. To date, although the nsLTP gene family of barley (Hordeum vulgare L.) has been preliminarily identified, it is still unclear in the recently completed genome database of barley and Qingke, and its transcriptional profiling under abiotic stress has not been elucidated as well. We identified 40 barley nsLTP (HvLTP) genes through a strict screening strategy based on the latest barley genome and 35 Qingke nsLTP (HtLTP) orthologues using blastp, and these LTP genes were divided into four types (1, 2, D and G). At the same time, a comprehensive analysis of the physical and chemical characteristics, homology alignment, conserved motifs, gene structure and evolution of HvLTPs and HtLTPs further supported their similar nsLTP characteristics and classification. The genomic location of HvLTPs and HtLTPs showed that these genes were unevenly distributed, and obvious HvLTP and HtLTP gene clusters were found on the 7 chromosomes including six pairs of tandem repeats and one pair of segment repeats in the barley genome, indicating that these genes may be co-evolutionary and co-regulated. A spatial expression analysis showed that most HvLTPs and HtLTPs had different tissue-specific expression patterns. Moreover, the upstream cis-element analysis of HvLTPs and HtLTPs showed that there were many different stress-related transcriptional regulatory elements, and the expression pattern of HvLTPs and HtLTPs under abiotic stress also indicated that numerous HvLTP and HtLTP genes were related to the abiotic stress response. Taken together, these results may be due to the differences in promoters rather than by genes themselves resulting in different expression patterns under abiotic stress. Due to a stringent screening and comprehensive analysis of the nsLTP gene family in barley and Qingke and its expression profile under abiotic stress, this study can be considered a useful source for the future studies of nsLTP genes in either barley or Qingke or for comparisons of different plant species.

中文翻译：

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非生物胁迫下大麦非特异性脂质转移蛋白基因家族及其青客直系同源物的全基因组鉴定和表达谱

植物非特异性脂质转移蛋白 (nsLTPs) 是一组小的、基本的普遍存在的蛋白质，参与脂质转移、角质层形成和应激反应，参与植物生长发育的调节。迄今为止，虽然大麦（​​Hordeum vulgare L.）的nsLTP基因家族已经初步确定，但在最近完成的大麦和青客基因组数据库中仍不清楚，其在非生物胁迫下的转录谱也未阐明。我们基于最新的大麦基因组和35个青科nsLTP（HtLTP）直系同源物，通过严格的筛选策略鉴定了40个大麦nsLTP（HvLTP）基因，这些LTP基因分为4种类型（1、2、D和G）。同时综合分析理化特性，同源比对，HvLTPs 和 HtLTPs 的保守基序、基因结构和进化进一步支持了它们相似的 nsLTP 特征和分类。HvLTPs和HtLTPs的基因组定位表明，这些基因分布不均，在大麦基因组中的7条染色体上发现了明显的HvLTP和HtLTP基因簇，包括6对串联重复序列和1对片段重复序列，表明这些基因可能是共同进化和共同调节的。空间表达分析表明，大多数 HvLTPs 和 HtLTPs 具有不同的组织特异性表达模式。此外，HvLTPs和HtLTPs的上游顺式元件分析表明存在许多不同的应激相关转录调控元件，非生物胁迫下HvLTPs和HtLTPs的表达模式也表明大量的HvLTP和HtLTP基因与非生物胁迫反应有关。总之，这些结果可能是由于启动子的差异而不是基因本身导致在非生物胁迫下不同的表达模式。由于对大麦和青稞中 nsLTP 基因家族及其在非生物胁迫下的表达谱进行了严格筛选和综合分析，本研究可被认为是未来大麦或青稞中 nsLTP 基因研究或比较不同植物品种。