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作 者 ：Cai Xue, Mu Xi-jin, Zhu Zhi-qing, Hua Zhi-ming, Huang Yan-hong and Sun Qi-xin

Keywords:Apomixis, Polyembryony, Multiple seedlings,

Abstract:Polyembryony and multiple seedlings in seeds of 6 different apomictic species were observed. The frequency of polyembryonic seed formation in FortuneUa margarita (Lour.) Swingle, Citrus unshiu Marcoritch and Zanthoxylum bungeanum 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 Malus 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 pelyembryonic 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, Poapratensis and Malus hupehensis was 22.00%, 6.14% and 2.22% respectively. Analysis was carried out with seeds containing a single embryo in Port pratensis, Elymus 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 pelyembryony 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.

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