Page 118 - 《广西植物》2026年第9期
P. 118

1 5 5 4                                广  西  植  物                                         46 卷
                 Abstract: The tribe Elatostemateae is the most species ̄rich tribe within the family Urticaceae Juss.ꎬ yet its taxonomic
                 study is significantly challenged by the convergent evolution of morphological traits. To gain a deeper understanding of
                 this tribes evolutionary adaptabilityꎬ this study employed the root ̄tip squash method for chromosome number
                 determination and utilized the flow cytometric seed screen (FCSS) to investigate the relationship between ploidy level
                 and reproductive pathways. Specificallyꎬ chromosome numbers of nine species were countedꎬ and reproductive pathways
                 of four species were examined. Furthermoreꎬ chromosome data from 62 species with known data in the tribe were
                 integrated and analyzed. The results were as follows: (1) Chromosome numbers for seven of the nine examined species
                 were reported here for the first time. The tribe exhibited complex chromosome basic number diversity and widespread
                 polyploidizationꎬ with the genera Elatostema and Pilea showing the most significant variability. This pattern was
                 hypothesized to be associated with their adaptation to the extreme karst habitatsꎻ at the chromosome basic number levelꎬ
                 Elatostema was predominantly characterized by x= 13ꎬ while Pilea was primarily characterized by x= 12. (2) The FCSS
                 results clearly demonstrated a consistent correlation between ploidy and reproductive pathwayꎬ diploid individuals
                 engaged in sexual reproductionꎬ whereas triploid individuals primarily formed seeds via apomixis. In conclusionꎬ
                 apomixis acts as a critical adaptive mechanism for circumventing the “triploid block”ꎬ the reproductive barrier faced by
                 odd polyploids during sexual reproductionꎻ the synergistic interplay of chromosome basic number variationꎬ
                 polyploidizationꎬ and apomixis within the tribe Elatostemateae is posited as a significant evolutionary driver for the
                 ecological adaptation and resulting diversification of its species in karst environments.
                 Key words: Elatostemateaeꎬ chromosome numberꎬ chromosome basic numberꎬ polyploidizationꎬ apomixisꎬ
                 cytologyꎬ phylogeny




                楼 梯 草 族 ( tribe Elatostemateae) 作 为 荨 麻 科      要显微镜观察的微观特征ꎬ显得尤为关键ꎮ 因此ꎬ
            (Urticaceae Juss.)物种多样性最丰富的族ꎬ包含 7                  在分类困难、存在大量趋同性状、隐存种以及杂交
            个 属 ( Fu et al.ꎬ 2025 ) 和 超 过 1 350 个 物 种          现象频繁的情况下ꎬ采用整合分类法是合理且必
            (https: / / powo.science. kew. org / )ꎮ 该族超过三 分    要的(洪 德 元ꎬ2016ꎻ梁 思 琪 等ꎬ2019ꎻ徐 奎 栋 等ꎬ
            之二的物种多样性由 2 个大属贡献ꎬ即楼梯草属                            2020ꎻMaltsev & Erstꎬ 2023ꎻ Fu et al.ꎬ 2025)ꎮ
            (Elatostema J. R. Forst. & G. Forst.) 和 冷 水 花 属        前人对楼梯草族的细胞学特征进行了总结ꎬ

            (Pilea Lindl.)ꎬ2 个属目前已接收学名均超过 600                  其中ꎬ楼梯草属的染色体基数类型为 x = 8ꎬ 12ꎬ
            个( https: / / powo. science. kew. org / )ꎮ 尽管楼梯 草  13ꎬ 14ꎬ 16 ( Sharma & Mehraꎬ 1979ꎻ Fu et al.ꎬ
            族植物的物种多样性高且分布广泛ꎬ但其属级界                              2017)ꎻ冷 水 花 属 为 x = 8ꎬ 12ꎬ ( 13) ( Sharma &

            定一 直 存 在 争 议 ( Wei et al.ꎬ 2011ꎻ Wu et al.ꎬ        Mehraꎬ 1979)ꎻ吐烟花属为 x = 13( Subramanian &
            2013ꎻ 王文采ꎬ2016ꎻ Tseng et al.ꎬ 2019)ꎮ 为更好           Thilagavathyꎬ 1988 )ꎻ 假 楼 梯 草 属 ( Lecanthus
            理解楼梯草族各属之间的亲缘关系ꎬ前人通过系                              Wedd.)为 x = 12(Sharma & Mehraꎬ 1979)ꎮ 上述研

            统发 育 和 形 态 学 分 析 进 行 了 探 索 ( Wu et al.ꎬ            究报道的楼梯草族染色体数目大多集中于少数
            2015ꎻ Tseng et al.ꎬ 2019ꎻ Fu et al.ꎬ 2022ꎻ Maciel  属ꎬ相关数据不仅数量有限ꎬ而且分布不均衡ꎮ 此
            et al.ꎬ 2023)ꎮ 例如ꎬ近期研究针对赤车属的多系                     外ꎬ相关细胞学文献较为分散ꎬ缺乏系统性整合和
            现状ꎬ将其大多数物种归入楼梯草属中ꎬ并将吐烟                             区域性比较ꎬ制约了对其分类价值和演化模式的
            花( Polychroa repens) 恢 复 为 吐 烟 花 属 ( Polychroa     深入理解ꎮ 截至目前ꎬ仅 62 个物种( 约占该族总

            Lour.) ( Tseng et al.ꎬ 2019ꎻ Monro et al.ꎬ 2025)ꎮ  物种数的 4%)有染色体数据( Rice et al.ꎬ 2015)ꎬ
            然而ꎬ传统分类方法面临诸多挑战ꎬ那些曾被视为                             并且缺乏属间的比较研究ꎮ
            关键的形态性状ꎬ实际频繁发生了趋同演化( Wu                                除作为分类研究的证据外ꎬ染色体数目和倍
            et al.ꎬ 2015ꎻ Washburn et al.ꎬ 2016ꎻ Tseng et al.ꎬ  性水平还与植物的生殖途径和演化模式密切相关
            2019ꎻ Fu et al.ꎬ 2022)ꎮ 在这样的背景下ꎬ细胞学                ( Fu et al.ꎬ 2017ꎻ van Drunen & Husbandꎬ 2019ꎻ
            证据(如染色体基数、核型与倍性等)ꎬ以及那些需                            Mráz & Šingliarováꎬ 2025)ꎮ 植物倍性与生殖途径
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