J Integr Plant Biol. ›› 2002, Vol. 44 ›› Issue (1): 15-21.

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The Structure of OryzaEmbryos and Their Dimorphic Cotyledons

XU Xue-Bin*, LIU Xiang-Dong, ZHANG Chong-Ling, WU Wan-Chun, HAN Hui-Zhen   

Abstract:

It has been generally held in botany that Oryza sativa L. is a monocotyledon. Based on studies of rice embryo development we confirmed that rice embryo has two dimorphic cotyledons rather than just one cotyledon. In the present study we attempt to know if the morphology of embryos in other species of Oryza differs from O. sativaand if these embryos have dimorphic cotyledon. Two types of embryo structures were observed in 22 species and/or subspecies of genus Oryza under the scanning electron microscope. Type 1, the O.sativatype, whichis characterized by ventral scale and lateral scales, was found in 16 species.Type 2, the O. meyeriana(Zoll. et Mor. ex Steud.) Baill. ssp. tuberculata W. C. Wu et Y. G. Lu, G. C. Wang type, with no ventral scale and lateral scales, was found in 6 species and subspecies. The embryogenic process of O.sativaand O.meyeriana sub. tuberculata showed that the scutellum primordium, coleorhiza primordium, coleoptile primordium and shoot apical meristem directly differentiate from proembryo. The former two later develop into the embryo envelope, which is the outside cotyledon; the coleoptile primordium develops into the coleoptile with the shape of inverted empty cone surrounding and covering the growth cone, which is the apical cotyledon. Both types of rice embryos have dimorphic cotyledons. The structural difference between them is that the scutellum primordium of the young embryo in type 2 does not differentiate ventral scale and lateral scales while the embryo of type 1 does. The dimorphic cotyledons of embryo of Oryza plants originate from the dorsiventrality of proembryo.

稻属植物胚的形态结构与二()型子叶

徐雪宾1*  刘向东1  章崇玲2  吴万春2  韩惠珍2

(1. 华南农业大学植物分子育种研究中心,广州 5106422. 华南农业大学植物学教研室,广州 510642)

摘要:长久以来植物学界认定稻(Oryza sativa L.)是单子叶植物.作者从稻胚发育的研究中确认稻胚具二型子叶,并非单子叶.稻属其他种的胚胎形态与O.sativa是否相同?是否具二型子叶?根据扫描电子显微镜的观察结果,稻属(Oryza) 22个种和亚种的胚的形态结构可以分为两种类型.O.sativa16个种胚具腹鳞和侧鳞,属第一类型;O. meyeriana (Zoll. et Mor. ex Steud.) Baill.ssp. tuberculata W. C. Wu et Y. G. Lu, G. C. Wang6个种(亚种)胚缺腹鳞和侧鳞,属第二类型.O.sativaO. meyeriana ssp. tuberculata的胚胎发育过程所出现的盾片原基、胚根鞘原基、胚芽鞘原基和生长锥均来自原胚,前二者发育成胚套,是外围子叶;胚芽鞘原基发育成围在生长锥外并盖住生长锥的空心的倒锥状胚芽鞘,是顶生子叶.第一类型与第二类型稻胚都具有二型子叶.第二类型稻胚在盾片原基发育过程中并不分化出腹鳞和侧鳞,因而造成第二类型稻胚缺腹鳞与侧鳞.稻的二型子叶源于原胚的背腹极性分化.

关键词 稻属 胚胎发生 二型子叶 背腹极性 胚套(外围子叶) 盾片与胚芽鞘(顶生子叶)

*通讯作者 Email: yglu@scau.edu.cn

 

Key words: genus Oryza, embryogenesis, dimorphic cotyledon, dorsiventrality, embryonic envelope (outside cotyledon), scutellum and coleoptile (apical cotyledon)

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