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Apomixis is a common reproductive characteristic of Zanthoxylum plants, and RWP-RKs are plant-specific transcription factors known to regulate embryonic development. However, the genome-wide analysis and function prediction of RWP-RK family genes in Z. armatum are unclear. In this study, 36 ZaRWP-RK transcription factors were identified in the genome of Z. armatum , among which 15 genes belonged to the RKD subfamily and 21 belonged to the NLP subfamily. Duplication events of ZaRWP-RK genes were mainly segmental duplication, and synteny analysis revealed a close phylogenetic relationship between Z. armatum and Arabidopsis . The analysis of cis-elements indicated that ZaRWP-RK genes may be involved in the regulation of the embryonic development of Z. armatum by responding to plant hormones such as abscisic acid, auxin, and gibberellin. Results of a real-time PCR showed that the expression levels of most ZaRWP-RK genes were significantly increased from flowers to young fruits. Protein-protein interaction network analysis further revealed the potential roles of the ZaRWP-RK proteins in apomixis. Collectively, this study is expected to improve our understanding of ZaRWP-RK transcription factors and provide a theoretical basis for future investigations into the ZaRWP-RK genes and their regulatory mechanisms in the apomixis process of Z. armatum .

Green prickly ash ( Zanthoxylum armatum ) has edible and medicinal value and is an economically significant plant in many countries. Z. armatum has many cultivars and varieties with similar phenotypes that are difficult to distinguish via traditional methods. In this study, we utilized oligo-FISH to distinguish five varieties and cultivars of Z. armatum on the basis of three oligonucleotide probes of 5S rDNA, (AG 3 T 3 ) 3 , and (GAA) 6 . Karyotype analysis of the five varieties and cultivars of Z. armatum showed that the Z. armatum 'Tengjiao' karyotype formula was 2 n = 2 x = 98 m with karyotype type 1C and an arm ratio of 4.3237, including two pairs of 5S rDNA signals and five pairs of (GAA) 6 signals. The karyotype formula of Z. armatum 'Youkangtengjiao' was 2 n = 2 x = 128 m + 8 sm with karyotype type 2B and an arm ratio of 3.5336, including three pairs of 5S rDNA signals and 17 pairs of (GAA) 6 signals. The karyotype formula of Z. armatum var. novemfolius was 2 n = 2 x = 134 m + 2 sm with karyotype type 1C and an arm ratio of 5.5224, including two pairs of 5S rDNA signals and eight pairs of (GAA) 6 signals. The karyotype formula of Z. armatum 'YT-03' was 2 n = 2 x = 2 M + 128 m + 4 sm + 2 st with karyotype type 2C and an arm ratio of 4.1829, including three pairs of 5S rDNA signals and nine pairs of (GAA) 6 signals. The karyotype formula of Z. armatum 'YT-06' was 2 n = 2 x = 126 m + 10 sm with cytotype 2B and an arm ratio of 3.3011, including three pairs of 5S rDNA signals and two pairs of (GAA) 6 signals. The five varieties and cultivars of Z. armatum had (AG 3 T 3 ) 3 signals on all chromosomes. The chromosomal symmetry of Z. armatum 'Tengjiao' was high, whereas the chromosomal symmetry of Z. armatum 'YT-03' was low, with the karyotypes of the five materials showing a trend toward polyploid evolution. The phylogenetic relationship between Z. armatum 'Tengjiao' and Z. armatum var. novemfolius was the closest, while that between Z. armatum 'YT-03' and Z. armatum 'YT-06' was closer than with Z. armatum 'Youkangtengjiao' according to oligo-FISH. The results provided a karyotype profile and a physical map that contributes to the distinction of varieties and cultivars of Z. armatum and provides strategies for distinguishing other cultivated species.