Singh Ajit Pratap, Johari Deepali, Khare Prem Behari
Pteridology Laboratory, CSIR-National Botanical Research Institute, 2-Rana Pratap Marg, Lucknow, U.P, 226 001, India.
J Plant Res. 2017 Mar;130(2):281-290. doi: 10.1007/s10265-016-0891-3. Epub 2016 Dec 24.
In-vitro studies of the ontogeny and mating system of the gametophytes of Lepisorus nudus were carried out through multispore and isolate cultures lasting 23 weeks. Spore germination begins early, on day 5-6. Spore germination pattern was Vittaria type and the germination percentage reached 82.69% (± 3.20%). Filamentous gametophyte did not branch and never produce separate prothalli. Occasionally the branching and separate prothalli were produced from mature and cordate gametophytes. Prothallial development was Drynaria type (cordate gametophytes with notched apex) contrary to other known species of Lepisorus, where gametophyte development was Kaulinia type (strap gametophytes without apical notch). Gametophyte production in multispore cultures reached up-to 75.6% (± 18.85%). All isolates initially produced archegonia and antheridia only after a prolonged cessation of production in archegonia. In contrast, only 37.2% (±12.63%) of individuals in multispore culture exhibited the same pattern with 29.8% (±7.56%) developing as males that did not produce archegonia by the end of the study. Only 37.2% (±12.63%) of archegoniate gametophytes developed antheridia by the end of the study and only once archegonia had degenerated; i.e., a temporal gap existed in expression of female and male gametangia. In multispore culture, only 26.21% (±5.70%) sporophytes developed on 160th day by fusion of female and male gametes that were derived from matings between sib gametophytes. In contrast, isolated gametophytes did not produce sporophytes. In isolate gametophytes, mature archegonia could not take delivery of male gametangia because antheridia were produced sequentially. This study suggests that the sequential expression of gametangia and absence of the intragametophytic selfing may also be a possible cause of reproductive barriers. Lepisorus nudus promotes inter-gametophytic selfing as an adaptive mechanism for reproductive success in multispore culture. This study presents a detailed account on reproductive biology of the taxa whose population is decreasing at distressing rate.
通过持续23周的多孢子和分离培养，对裸叶瓦韦配子体的个体发育和交配系统进行了体外研究。孢子在第5 - 6天就早早开始萌发。孢子萌发类型为书带蕨型，萌发率达到82.69%（±3.20%）。丝状配子体不分支，从不产生单独的原叶体。偶尔，成熟的心形配子体会产生分支和单独的原叶体。原叶体发育为槲蕨型（顶端有缺刻的心形配子体），这与其他已知的瓦韦属物种不同，后者的配子体发育为考林型（无顶端缺刻的带状配子体）。多孢子培养中配子体的产生率高达75.6%（±18.85%）。所有分离的配子体最初只产生颈卵器，在颈卵器长时间停止产生后才产生精子器。相比之下，多孢子培养中只有37.2%（±12.63%）的个体表现出相同的模式，29.8%（±7.56%）发育为雄性，到研究结束时不产生颈卵器。到研究结束时，只有37.2%（±12.63%）的有颈卵器的配子体发育出精子器，且只有在颈卵器退化后才发育；即雌雄性器官的表达存在时间间隔。在多孢子培养中，只有26.21%（±5.70%）的孢子体在第160天通过来自同胞配子体交配产生的雌雄性配子融合而发育。相比之下，分离的配子体不产生孢子体。在分离的配子体中，成熟的颈卵器无法接受雄配子体，因为精子器是依次产生的。这项研究表明，性器官的顺序表达和配子体内自交的缺失也可能是生殖障碍的一个可能原因。裸叶瓦韦促进配子体间自交，作为多孢子培养中繁殖成功的一种适应机制。这项研究详细阐述了该分类群的生殖生物学，其种群正以惊人的速度减少。
