Abstract: The development of alfalfa floral organs is studied in detail by Scanning Electron Microscope. Results show that eight developmental stages (S1~S8) of floral organ are observed under the electron microscope. The differentiation of primary inflorescence meristem (I1) and secondary inflorescence meristem (I2) are found in S1. I2 grows into flower meristem (F) and the bracts (Br) in following S2. Single sepal primordium (Sab) appears in S3 then differentiates into carpel primordial (C) and common primordium in S4. Common primordium differentiates into petal primordium(P) and stamen primordium in S5. Sepal starts elongation in S6 then covers other flower primordials and both sides of the stamen primordia (STs) as well as stamen primordia (STp) which is close to the carpel and is beginning to differentiate into stamens. Vexillum and alae petals differentiate obviously, keel petals begin to fuse, stigma collapses in immature stamen and stamen differentiates clearly in S7. Entire flower development is completed, stigma begins to stretch and anther becomes mature in S8. The stamen primordium of Huaiyin alfalfa produces original winged-shaped anthers, and the pollen grains belong to type N3P4C5. This study not only lays a foundation for the research of alfalfa male sterility, self-incompatibility, flower development mode, anther culture and flower mutant fertility, but also provides guidance to molecular biology and developmental genetics of alfalfa floral development.

Key words: Alfalfa, Common primordium, Development, Ather, Pollen

摘要： 利用扫描电镜对苜蓿(Medicago sativa)花器官的发育过程进行详细研究。结果表明:在电镜下将苜蓿花器官的发育分为明显的8个阶段,S1阶段出现初级花序分生组织(I1)和次级花序分生组织(I2)的分化;S2阶段次级花序分生组织发育为花分生组织(F)和苞片(Br);S3阶段出现萼片原基(Sab);S4阶段分化心皮原基(C)和共同原基;S5阶段共同原基分化为花瓣原基(P)和雄蕊原基(STp);S6阶段萼片开始伸长,并覆盖其他花原基,两侧的雄蕊原基(STs)和靠近心皮的雄蕊原基(STp)开始分化雄蕊;S7阶段旗瓣和翼瓣分化明显,龙骨瓣融合,柱头折叠在未成熟的雄蕊之间,雄蕊分化明显;S8阶段整个花器官发育完成,柱头开始伸展,花药生长趋于成熟。淮阴苜蓿雄蕊原基产生四棱形的花药原始体,淮阴苜蓿花粉粒属 N3P4C5型。该试验将对苜蓿雄性不育、自交不亲和、花的发育模式、花药培养及相关花的突变体育性的研究奠定基础,并对苜蓿花发育的分子生物学和发育遗传学研究提供指导。

关键词: 苜蓿, 共同原基, 发育过程, 花药, 花粉