芍药胚和胚乳早期发育的研究

本文报道芍药(Paeonia lactiflora)的胚和胚乳的早期发育,主要结论是:1,开花后4—20天,合子核反复分裂形成多核原胚。2.原胚及胚乳游离核分裂均以有丝分裂为主,晚期有无丝分裂和多倍体核;3,细胞壁形成可由纺锤丝间和自由壁两种方式进行。原胚壁形成由合点端向珠孔端进行,胚乳则由胚附近向合点端发展。我们支持 Cave 等基于多核原胚提出的 Paeonia 与裸子植物平行演化的意见,同时认为 Paeonia 的多核原胚演化趋势是原胚由珠孔端至合点端功能分区的特化。

THE EARLY DEVELOPMENT OF EMBRYO AND ENDOSPERM OF PAEONIA LACTIFLORA

The present paper reports the early development of embryo and endo- sperm of Paeonia lactiflora.The main conclusions are as follows: 1 The zygote nucleus divides directly to form a coenocytic proembryo with dif- ferent number of free nuclei.The result confirms the conclusion of Yakovlev as well as Yakovlev and Yoffe On the occurnce of coenocytic proembryo in Paeonia suffru- ticosa Andr.(P.moutan Sims),P.albiflora Pall.(P.lactiflora Pall),P.officinalis L.,P.tenuifolia L.,P.anomala L.,P.veitchii Lynch (P.beresowskii Komarov),P. wittmanniana,also it agrees with the report of Cave et al.on the occurence of the coenocytic Proembryo in Paeonia californica and P.brownii.From the result of our investigation,there is no basis to support Murgai's conclusion obtained in certain spe- cies of Paeonia,i.e.,the first division of zygote nucleus is accompanied by wall for- mation and the coenocyte is a suspensor.The primary endosperm nucleus of P.lacti- flora divides often earlier than zygote nucleus,or almost at the same time or later in a few cases;2 Both mitosis and amitosis occur in the free nuclei in the coenocytic proembryo,and mitosis is dominant.In the later stage of development the amitosis occurs at the micropylar region of the coenocytic proembryo,in the free nuclear endo- sperm at the chalazal region and the appressed part of the chalazal end of the coenocy- tic proembryo.In addition,in the region of conenocytic proembryo and endosperm po- lyploid nuclei,irregular nuclei are also frequently met with;3 Cell wall formation in the coenocyte and the endosperm initiates by means of both cell plate and freely grow- thing walls,but in the coenocyte wall formation is earlier than in the free nuclear endo- sperm.At first,wall formation of the coenocytic proembryo begins at the chalazal end, and then extends toward the micropylar region,and in endosperm it begins at the part appressed to the part of the chalazal end of coenocytic proembryo,and then extends toward the chalazal end. We support Cave's suggestion of the parallel evolution for Paeonia possessed the coenocytic proembryo has no relation to the coenocytic proembryo of the gymnosperms. Further we consider the evolution tendency of the coenocytic proembryo of Paeonia toward a functional specialization.