Maize was one of the first eukaryotic species in which individual chromosomes can be identified cytologically, which made maize one of the oldest models for genetics and cytogenetics research. Nevertheless, consistent identification of all 10 chromosomes from different maize lines as well as from wild Zea species remains a challenge. We developed a new technique for maize chromosome identification based on fluorescence in situ hybridization (FISH). We developed two oligonucleotide-based probes that hybridize to 24 chromosomal regions. Individual maize chromosomes show distinct FISH signal patterns, which allow universal identification of all chromosomes from different Zea species. We developed karyotypes from three Zea mays subspecies and two additional wild Zea species based on individually identified chromosomes. A paracentric inversion was discovered on the long arm of chromosome 4 in Z. nicaraguensis and Z. luxurians based on modifications of the FISH signal patterns. Chromosomes from these two species also showed distinct distribution patterns of terminal knobs compared with other Zea species. These results support that Z. nicaraguensis and Z. luxurians are closely related species.

中文翻译：

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玉米和野生玉米种子的通用染色体鉴定系统。

玉米是最早可以通过细胞学鉴定单个染色体的真核生物之一，这使玉米成为最古老的遗传学和细胞遗传学研究模型之一。然而，如何连续鉴定来自不同玉米品系以及野生玉米品种的所有10条染色体仍然是一个挑战。我们开发了一种基于荧光原位杂交（FISH）的玉米染色体鉴定新技术。我们开发了两种与24个染色体区域杂交的基于寡核苷酸的探针。单个玉米染色体显示出不同的FISH信号模式，从而可以普遍鉴定来自不同Zea物种的所有染色体。我们根据个体鉴定的染色体，从三个玉米亚种和两个其他野生玉米亚种开发了核型。基于FISH信号模式的修饰，在尼加拉瓜Z. luxurians和4号染色体的长臂上发现了一个副中心反转。与其他Zea物种相比，这两个物种的染色体还显示出不同的末端结分布模式。这些结果支持尼加拉瓜Z.和luxurians是密切相关的物种。