Local cultivars of pearl millet in Saudi Arabia are known to tolerate extreme heat and drought stress. In the current study, the sequences of internal-transcribed spacers (ITSs) of six pearl millet cultivars were sequenced and analysed to investigate the genetic diversity among the local cultivars. The nucleotide polymorphism, secondary structures and phylogenetics were analysed for ITS sequences of the six local cultivars. The obtained sequences were 772–774 base pairs (bp) in length, including complete sequences of the ITS1–5.8S–ITS2 region and partial sequences of 18S and 26S rRNA. The nucleotide diversity among cultivars was higher in ITS2 sequences than ITS1 sequences. The ITS2 had four variable nucleotide sites in three native cultivars, whereas the ITS1 contained one base insertion. The secondary structures of the ITS1 and 5.8S region were highly conserved among the six cultivars and contained some motifs that are conserved across Viridiplantae. However, the ITS2 secondary structure for the two native cultivars, Sayah and Jazan, was distinct from the other cultivars, which confirms the applicability of the ITS2 sequence in distinguishing between genetically close taxa. Additionally, the phylogenetic analysis of the six investigated cultivars and 31 pearl millet accessions from the NCBI database showed close relationships between the local accessions and NCBI accessions from India and France. However, the local cultivar Sayah appeared to be distinct from the other cultivars in the phylogenetic trees. This study provides insights into the polymorphism within local pearl millet cultivars which is important for the identification and conservation of these cultivars.

中文翻译：

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利用核糖体 DNA 内转录间隔对当地珍珠粟品种进行分子鉴定和系统发育研究

众所周知，沙特阿拉伯的当地珍珠粟品种能够耐受极端高温和干旱胁迫。在目前的研究中，对六个珍珠粟品种的内转录间隔区（ITS）序列进行了测序和分析，以调查当地品种之间的遗传多样性。对6个地方栽培品种的ITS序列进行核苷酸多态性、二级结构和系统发育分析。获得的序列长度为772-774个碱基对（bp），包括ITS1-5.8S-ITS2区域的完整序列和18S和26S rRNA的部分序列。ITS2序列的核苷酸多样性高于ITS1序列。ITS2 在三个本地栽培品种中有四个可变核苷酸位点，而 ITS1 包含一个碱基插入。ITS1 和 5 的二级结构。8S 区域在六个品种中高度保守，并且包含一些在草本植物中保守的基序。然而，这两个本地品种 Sayah 和 Jazan 的 ITS2 二级结构与其他品种不同，这证实了 ITS2 序列在区分遗传上接近的分类群中的适用性。此外，对 6 个被调查品种和 NCBI 数据库中的 31 个珍珠粟种质的系统发育分析表明，当地种质与印度和法国的 NCBI 种质之间存在密切关系。然而，当地品种 Sayah 似乎与系统发育树中的其他品种不同。本研究提供了对当地珍珠粟品种多态性的深入了解，这对于这些品种的鉴定和保护很重要。