几种具无融合生殖特性的植物多胚和多苗现象的观察

报道6种具无融合生殖特性的植物种子的胚数和萌发实生苗数的观察结果。金桔(Fortunellamargarita (Lour.)Swingle)、蜜桔(Citrus unshiu Marcoritch)和花椒(Zanthoxylum bungeanum Maxim.)具珠心胚,含多胚种子频率分别为97.50％、100％和45.00％;多胚种子的胚数范围分别为2～49,3～54和2～6。草地早熟禾(Poa pratensis L.)、滨草(Elymus rectisetus)和湖北海棠(Malus hupehensis(pampon.)Rehd.)具非减数配子体无融合生殖特性,含多胚种子频率依次为34.25％、8.11％和37.50％;前两种的多胚种子中胚数范围为2～3,后者为2～15。蜜桔、草地早熟禾和湖北海棠种子萌发多苗的频率分别为22.00％、6.14％和2.22％。描述了多胚种子中胚的形态、位置和分布。对6种植物含单胚种子的胚的来源进行了分析。初步结论:1.具无融合生殖现象的植物种子含多胚和萌发多苗的特性可作为寻找具无融合生殖特性的植物的形态学指标;2.对其筛选的材料进行大孢子发生、胚囊形成和早期胚胎发育的研究,以期阐明多胚来源和生殖类型。

POLYEMBRYONY AND MULTIPLE SEEDLINGS IN THE APOMICTIC PLANTS

Polyembryony and multiple seedlings in seeds of 6 different apomictic species were observed. The frequency of polyembryonic seed formation in Fortunella margarita (Lour.) Swingle, Citrus unshiu Marcoritch and Zanthoxylum bungeamim Maxim., all of which were characterized by the occurrence of adventitious embryo directly formed from a somatic cell of the ovule, was 97.50% , 100% and 45.00% respectively.The number of embryo per polyembryonic seed ranged from 2 to 49,3 to 54 and 2 to 6 respectively. In Poa pratensis L., Elymus rectisetum and Mains hupehensis (Pampan) Rehd., characterized by the gametophyte apomixis, the embryo of which arised directly from the egg cell of the unreduced embryo sac, and the frequency of polyembryonic seed was 34.25% , 8.11% and 37.50% respectively.The number of embryo per polyembryonic seed ranged from 2 to 3 for the former two species, and 2 to 15 for the latter. The frequency of multiple seedlings in Fortunella margarta,Poa pratensis and Mains hupehensis was 22.00% , 6.14% and 2.22% respectively. Analysis was carried out with seeds containing a single embryo in Poa pratensis, Elyihus rectisetum, Malus hupehensis and Citrus. The morphological variation, position and distribution of embryos in polyembryonic seed were also described. The authors' primary conclusions are as follows: 1. The phenomena of polyembryony and multiple seedlings of apomictic plant could be used as sketchy screening indicator for identifying plants tending to be apomictic; 2. In order to characterize the apomictic type, specific studies in macrosporogenesis, the development of embryo sac and the early embryogenesis might be very important considerations as embryological evidence of the possibility of apomictic formation of the seed in the tested plants.