无核荔枝假种皮发育过程的研究

无核荔枝是荔枝中较为珍贵的品系 ,种子多退化 ,故为无核品系。其胚珠在发育过程中由于胚囊败育而萎缩 ,假种皮发生于珠脊外侧及外珠被外侧 ,由于胚珠中部的表皮及表层下的几层细胞先后脱分化形成分生组织 ,而在以后的发育中经历一个由“中层”假种皮发育到“平台”假种皮的过程 ,当“平台”假种皮形成以后 ,在其外侧边缘形成一个明显的“上翘”假种皮 ;继而 ,把发育缓慢的胚珠和珠柄包埋 ,而形成“无核”。此外 ,在其发育过程中 ,外界温度对其影响较为明显 :扬花期的高温会产生大核、焦核 ,低温则产生无核 ,因此 ,无核荔枝可能是低温敏感型。

Study on developmental process of aril in seedless-litch

The seedless-litchi is one of the valuable variety in Litchi chinensis Sonn. It has rich aril, and most of the seeds are degenerated, so it belongs to the seedless type. As the aril grew, ovule became atrophied as a result of embryo sac degeneration, the aril originates from the outside raphe and outside ovule integument, as the cells that in epidermis and under the epidermal layers of middle ovule dedifferentiated and formed the meristematic tissue. In the later period of aril's development, the aril originates from the "middle" aril to the "platform" aril, and after the "platform" aril were formed, it took shape a clearing "ascent" aril in the outside "platform" aril. After showed no obvious developmental changes, even though the aril had expanded greatly, wrapping up the underdeveloped ovule and funicle. In addition, during flowering period, the outside temperature has clear effect on seed's formation, the high temperature produce large-seeded and small-seeded fruits, and the low temperature produce seedless fruits. So the seedless-litchi may be a type of low sensitivity of temperature.