濒危植物小勾儿茶大小孢子发生和雌雄配子体发育

Megasporogensis,Microsporogenesis and Development of Male and Female Gametophytes of Endangered Berchemiella wilsonii

运用石蜡切片技术对小勾儿茶(Berchemiella wilsonii)进行生殖生物学观察,探讨其大小孢子发生和雌雄配体发育过程是否存在濒危环节。结果显示:小勾儿茶的花具5个雄蕊和4个花药室,成熟的花药壁由花药内壁(1层)、中层(2层)和绒毡层(1层)组成。绒毡层发育正常,细胞排列整齐规则,与中层细胞联系紧密,细胞中常多核。小孢子母细胞在减数分裂时胞质分裂方式为同时型,四分体主要以四面体形式存在,花粉粒在成熟时为二细胞型、圆形或椭圆形,多数有3根萌发管。花药发育过程中绒毡层发育存在少量异常,花粉存在少量败育。小勾儿茶子房2室,只发育1室。胚珠为倒生的双珠被和厚珠心,合点端大孢子发育成功能性大孢子,经过3次有丝分裂,进一步发育成具有7个细胞和8个核的胚囊,胚囊发育方式为蓼型。子房中的胚珠发育基本一致。小勾儿茶大小孢子发生和雌雄配子体发育基本正常,不是导致其结实率低的原因。

To explore whether there were any endangered links in sporogenesis and development of male and female gametophyte of endangered Berchemiella wilsonii,the reproductive biology of B.wilsonii was observed using paraffin section technique.The results showed that the flower of B.wilsonii had five stamens,four anthers,and the mature anther wall was composed of one inner layer,two middle layers and one tapetal layer.The tapetum developed normally with regularly arranged cells closely connected with the middle layer cells containing multiple nuclei in each cell.The cytoplasmic division of microspore mother cells was synchronous during meiosis,and mainly formed tetrahedral tetrads,the mature pollen grains were bicellular,round or oval in shape,which most of them had three germinating tubes.There were a few abnormal tapetum development and a few abortive pollen during anther development.B.wilsonii had two locule in ovary,only one chamber developed.The ovule was anatropous double integuments and crassinucellate.The chalazal end megaspore developed into functional megaspores,which underwent three times consecutive mitosis and further developed into polygonum embryo sac with seven cells and eight nucleus.Ovary ovule development was basically synchronized.The process of the mega-microsporogenesis and development of female and male gametophyte of B.wilsonii were normal,which was not the reason for the low seed setting rate.