Embryology of Swertia (Gentianaceae) relative to taxonomy

	Embryology of Swertia (Gentianaceae) relative to taxonomy
	Xue, Chun-Ying ; Ho, Ting-Nong ; Li, De-Zhu
刊名	BOTANICAL JOURNAL OF THE LINNEAN SOCIETY ; Xue ChunYing,Ho TingNong,Li DeZhu.Embryology of Swertia (Gentianaceae) relative to taxonomy.BOTANICAL JOURNAL OF THE LINNEAN SOCIETY,2007,155(3):383-400
	2007-11-01
英文摘要	The embryological features of three species of Swertia (s.l.) - S. erythrosticta, S. franchetiana, and S. tetraptera were characterized, and the observations were used, together with previously gathered data on other species, to evaluate a recently proposed polyphyly, based on molecular data, of Swertia s.l. Comparisons of species within the genus showed that they have diversified embryologically, and there are significant between-species differences. Notable features that vary between species include the number of cell layers that form the anther locule wall, the construction of the wall of the mature anther, tapetum origin, the cell number in mature pollen grains, the structure of the fused margins of the two carpels, the ovule numbers in placental cross-sections, the shape of the mature embryo sac, the degree of ovule curvature, antipodal variation and the presence of a hypostase, and seed appendages. They share characters that are widely distributed in the tribe Gentianeae, such as a dicotyledonous type of anther wall formation, a glandular tapetum with uninucleate cells, simultaneous cytokinesis following the meiosis of the microsporocytes, tetrahedral microspore tetrads, superior, bicarpellary and unilocular ovaries, unitegmic and tenuinucellar ovules, Polygonum-type megagametophytes, progamous fertilization, nuclear endosperm, and Solanad-type embryogeny. The presence of variation in embryological characters amongst the species of Swertia s.l. strongly supports the view that Swertia s.l. is not a monophyletic group. Frasera is better separated from Swertia s.l. as an independent genus, and is only distantly related to Swertia s. s. judging from the numerous differences in embryology. Swertia tetraptera is very closely related to Halenia, as they show identical embryology. (C) 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 383-400.; The embryological features of three species of Swertia (s.l.) - S. erythrosticta, S. franchetiana, and S. tetraptera were characterized, and the observations were used, together with previously gathered data on other species, to evaluate a recently proposed polyphyly, based on molecular data, of Swertia s.l. Comparisons of species within the genus showed that they have diversified embryologically, and there are significant between-species differences. Notable features that vary between species include the number of cell layers that form the anther locule wall, the construction of the wall of the mature anther, tapetum origin, the cell number in mature pollen grains, the structure of the fused margins of the two carpels, the ovule numbers in placental cross-sections, the shape of the mature embryo sac, the degree of ovule curvature, antipodal variation and the presence of a hypostase, and seed appendages. They share characters that are widely distributed in the tribe Gentianeae, such as a dicotyledonous type of anther wall formation, a glandular tapetum with uninucleate cells, simultaneous cytokinesis following the meiosis of the microsporocytes, tetrahedral microspore tetrads, superior, bicarpellary and unilocular ovaries, unitegmic and tenuinucellar ovules, Polygonum-type megagametophytes, progamous fertilization, nuclear endosperm, and Solanad-type embryogeny. The presence of variation in embryological characters amongst the species of Swertia s.l. strongly supports the view that Swertia s.l. is not a monophyletic group. Frasera is better separated from Swertia s.l. as an independent genus, and is only distantly related to Swertia s. s. judging from the numerous differences in embryology. Swertia tetraptera is very closely related to Halenia, as they show identical embryology. (C) 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 383-400.
内容类型	期刊论文
源URL	[http://ir.nwipb.ac.cn/handle/363003/1251]
专题	西北高原生物研究所_中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	Xue, Chun-Ying,Ho, Ting-Nong,Li, De-Zhu. Embryology of Swertia (Gentianaceae) relative to taxonomy[J]. BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Xue ChunYing,Ho TingNong,Li DeZhu.Embryology of Swertia (Gentianaceae) relative to taxonomy.BOTANICAL JOURNAL OF THE LINNEAN SOCIETY,2007,155(3):383-400,2007.
APA	Xue, Chun-Ying,Ho, Ting-Nong,&Li, De-Zhu.(2007).Embryology of Swertia (Gentianaceae) relative to taxonomy.BOTANICAL JOURNAL OF THE LINNEAN SOCIETY.
MLA	Xue, Chun-Ying,et al."Embryology of Swertia (Gentianaceae) relative to taxonomy".BOTANICAL JOURNAL OF THE LINNEAN SOCIETY (2007).