Oligonucleotide (Oligo)-based fluorescence in situ hybridization (FISH) represents a highly effective methodology for identifying plant chromosomes. Longan is a commercially significant fruit species, yet lacking basic chromosomal markers has hindered its cytogenetic research. In this study, we developed a cost-effective oligo-based system for distinguishing chromosomes of longan (Dimocarpus longan Lour., 2n = 2x = 30). For this system, each synthesized oligo contained two chromosome-specific sequences that spanned a distance of over 200 kb, and a PCR-based flexible amplification method coupled with nested primers was used for probe labeling. The use of these oligo-based barcodes enabled the marking of 36 chromosomal regions, which allowed for the unambiguous distinction of all 15 chromosomes in both longan and lychee (Litchi chinensis Sonn., 2n = 2x = 30) species. Based on the identification of individual chromosomes, we constructed karyotypes and detected genome assembly errors involving the 35S ribosomal RNA gene (35S rDNA) in longan and lychee. Developing oligo-based barcodes offers considerable promise for advancing cytogenetic research in longan, lychee, and their related species. Furthermore, this cost-effective synthesis system can be referred to the development of new oligo libraries among other species.

中文翻译：

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一种经济有效的基于寡核苷酸的条形码系统，用于龙眼和荔枝的染色体识别


基于寡核苷酸 (Oligo) 的荧光原位杂交 (FISH) 代表了一种识别植物染色体的高效方法。龙眼是一种具有重要商业价值的水果品种，但缺乏基本的染色体标记阻碍了其细胞遗传学研究。在这项研究中，我们开发了一种经济高效的基于寡核苷酸的系统，用于区分龙眼（Dimocarpus longan Lour., 2n = 2x = 30）的染色体。对于该系统，每个合成的寡核苷酸包含两个跨度超过200 kb的染色体特异性序列，并且使用基于PCR的灵活扩增方法与嵌套引物相结合来进行探针标记。使用这些基于寡核苷酸的条形码可以标记 36 个染色体区域，从而可以明确区分龙眼和荔枝 (Litchi chinensis Sonn., 2n = 2x = 30) 物种的所有 15 条染色体。基于个体染色体的鉴定，我们构建了龙眼和荔枝中涉及35S核糖体RNA基因（35S rDNA）的核型并检测了基因组组装错误。开发基于寡核苷酸的条形码为推进龙眼、荔枝及其相关物种的细胞遗传学研究提供了广阔的前景。此外，这种具有成本效益的合成系统可以参考其他物种中新寡核苷酸库的开发。