罗汉果大孢子发生及雌配子体发育与花部形态、胚珠变化的关系

Relationship between Megasporogenesis, Development of Female Gametophyte and Related Morphological Changes of Flower, Ovule in Siraitia grosvenorii

为弄清罗汉果(Siraitia grosvenorii)大孢子发生、雌配子体发育过程与花部形态特征、胚珠的关系,运用石蜡切片法对罗汉果子房进行了显微观察。结果表明,罗汉果的胚珠倒生,双珠被,厚珠心,大孢子四分体呈线型排列,合点端一个大孢子分化为功能大孢子,成熟胚囊为蓼型。花蕾形态、胚珠变化与大孢子发生、雌配子体的发育时期具有一定相关性,当子房长度为7.0 mm≤L<9.0 mm,珠心呈椭圆形时,约有45.83%的大孢子母细胞处于减数分裂时期。因此,依据罗汉果花部形态可有效确定大孢子发生与雌配子体发育的时期。

The aim of this study was to find the relationship between megasporogenesis, development of female gametophyte and morphological changes of flower, ovule in Siraitia grosvenorii. The ovaries were observed under light microscope by means of paraffin wax fixation. The results showed that ovule of Siraitia grosvenorii was anatropous, bitegmic and erassinucellar. The chalazal megaspore of linear tetrad developed into Polygonum- type embryo sac. Morphological changes of flower and ovule indicated different developmental stages of megasporogenesis and female gametophyte. As the length of ovary ranged from 7 to 9 mm and the nucellus were oval-shape, 45.83% megaspore mother cells were at the stage of meiosis. These suggested that the morphological characteristics of flower and ovule could be used to distinguish different stages of megasporogenesis and female gametophyte development of Siraitia grosvenorii.