荒漠早春开花植物囊果草大小孢子发生及雌雄配子体发育

Sporogenesis and Gametogenesis in an Early-spring-flowering Perennial Leontice incerta(Berberidaceae)in the Desert

囊果草(Leontice incerta Pall.)为生长于天山北坡荒漠和低山山坡的小檗科(Berberidaceae)多年生早春开花植物,具有较高的观赏价值、饲用价值和生态价值,为探究该物种的有性生殖特征,并为后续进行栽培育种等工作提供理论依据,作者利用光学显微镜和石蜡制片技术,对该物种大/小孢子发生和雌/雄配子体发育进行了观察。结果表明,(1)花药具4室,药壁由5层细胞组成,发育为基本型。药室内壁在发育后期具纤维状加厚现象;腺质型绒毡层具2核或多核现象。(2)小孢子母细胞减数分裂时胞质分裂为同时型;小孢子四分体为四面体型,被胼胝质壁所包围,游离小孢子形成后胼胝质壁逐渐消失。成熟花粉多为2细胞型,偶见3细胞型。(3)雌蕊由1心皮组成,子房1室,倒生胚珠,具双珠被,厚珠心。大孢子四分体呈线形排列,最终发育为7细胞8核的蓼型胚囊,助细胞具发达的漏斗形丝状器。这些特点说明,囊果草大/小孢子发生和雌/雄配子体发育正常,未见败育现象,表现出较原始的发育特征。研究结果丰富了小檗科植物的胚胎学资料,为该物种及其近缘物种的生殖生物学研究积累了理论基础。

Leontice incerta is a perennial early-spring flowering plant of the Berberidaceae,which grows in the cold deserts and low hills in northern of the Tianshan Mountains,Xinjiang,China,which has ornamental value,feeding value and ecological value.In order to explore the sexual reproductive traits of this species and provide a theoretical basis for subsequent cultivation and breeding work,authors observed the megasporogenesis and microsporogenesis and development of female and male gametophytes of this species by optical microscope and paraffin sectioning technique.The results show that,(1)anthers of this species are tetradymous,and the wall of the anther consists of 5 layers of cells and develops into a basic type.The endothecium shows fibrous thickening in the later stage of development.The glandular tapetum has two or multiple nuclei.(2)Cytokinesis of the meiosis of microspore mother cells is simultaneous,the microspore tetrads are arranged in tetrahedral type.The wall of tetrads becomes thicker by the deposition of callose and when free microspores are formed,the callose wall is gradually dissolved.Mature pollen grains are mostly 2-cell type,occasionally 3-cell type.(3)The pistil of this species has a single carpel.The ovary has one chamber,and the ovules are anatropous with bitegmic and crassinucellate.The megaspore tetrad is arranged in a linear and eventually develops into a polygonum embryo sac with 7-cell and 8-nucleus.Synergids have well-developed funnel-shaped filiform apparatus.These features illustrate that the megasporogenesis and microsporogenesis and development of female and male gametophytes in L.incerta are normal,and no abortion was observed,showing more original developmental traits.The results enrich the embryological data of the Berberidaceae,and accumulate theoretical basis for the study of reproductive biology of this species and its related species.