Study On The Pollen Morphology And Pollen Development Of Liliaceae Ⅱ

Systemic studies on the morphology,structure and development of pollen in Liliaceae have been done by paraffin sectioin and electron microscope technique,especially on the anther's structure,pollen ontogeny,the behavior of callose wall of microspore mother cells(MMCs) during the meiosis,the depositing of sporopollenin,the function of the ubisch body during the development of pollen wall and the taxonomic value of the Ubisch body,etc.The results as following:1.The pollen morphology in LiliaceaeThe pollen grains of 5 species belonging to 5 genera in Liliaceae,i.e.,Allium senescens L., Cardiocrinum giganteum(Wall.) Makina,Maianthemum bifolium(Linn.) F.W.Schmidt.,Smilax discotis Warb.,Hemerocallis middendorfii Trautv.et Mey.were observed using light or scanning electronic microscopes.Then they were compared with others such as Hosta Tratt., Chlorophytum capense(L.) Kuntze,Hemerocallis citrina Baroni,Fritillaria maximowiczii Freyn, Lilium pumilum DC.,and Paris verticillata M.-Bieb on the purpose of providing palynological evidence for the systematic evolution and the identify of fossil pollen of Liliaceae.Based on the studies,some conclusions are drawn as follows:The pollen grains of Liliaceae are generally elliptic or round,with monocolpate(distal),and the sculptures are reticulate. However,the pollen grains of Smilax L.are obviously different from others in Liliaceae which are spheroidal,inaperturate,with spinulate or microspinulate.Thus we supported to establish a new family-Smilaeaceae.2.The pollen ontogeny in LiliaceaeThe pollen development of A.senescens L.,C.giganteum(Wall.) Makina,M.bifolium (Linn.) F.W.Schmidt.,and Veratrum nigrum L.were studied by paraffin section and LM especially on the microsporogenesis,male-gametogenesis and the corresponding development of anther wall in order to accumulate data on embryology and sexual reproduction,and to provide evidence for analyzing the phylogenetic classification and the systematic evolutionary relation.The results showed that the anther wall generally includes 4 layer cells:epiderm, endothecium,middle layer and secretory tapetum.The middle layer varies in some genus.And the anther wall of Cardiocrinum(Endl.) Lindl.is the most complex,which comprises 1 epiderm, 2 endothecium,4-5 middle layers and 2 secretory tapetum.Successive cytokinesis in the microsporocyte meiosis accompanies to produce mainly isobilateral or tetragonal tetrads,and less T shaped or liner tetrads.The mature pollen is 2-celled,while 3-celled type only exists in rare genus.One species always has only one type.But in A.senescens L.,both binucleate and trinucleate pollen occur in a single species.So we suppose that Allium L.may be the transitional genus in systematic evolution.In addition,there are many raphides in cells of perianth,anther wall,and ovary wall in mostly genus of Liliaceae except Allium L.and Cardiocrinum(Endl.) Lindl. There are some abnormal phenomena at meiosis of MMCs and male-gametogenesis in Allium L,including laggard chromosome,chromosome fragments,bridges,double-bridges, micronuclei and so on.It's might be one of the reasons causing abortive pollen.Furthermore,the anther of Smilax L.was found to be 2-sporangiate.It's also dissimilarity to others in Liliaceae.3.The dynamic changes of callose in MMCs during the meiosisThe method for callose fluorescence observation of MMCs during the meiosis is improved. After stained by improved carbol fuchsin-aniline blue fluorescence,the photos are vivid and colorful with red cytoplasm,carmine chromosomes,kelly callose,and demonstrate a three-dimensional effect.Cytoplasm and chromosomes appear as red fluorescence under the excitation of blue light and the chromosomes are clear,if they are stained only by improved carbol fuchsin.Therefore,improved carbol fuchsin can be used as the fluorochrome to nuclear DNA to substitute such expensive DNA-specific fluorochrome such as DAPI and H33258 in order to reduce the cost of experiment.By this method,the dynamic changes of callose in H.middendorfii Trautv.et Mey.and C. giganteum(Wall.)Makino,were observed.The callose deposits in the centre of MMC and form the centrifugal cell plate in H.middendorfii Trautv.et Mey.On the other hand,in C.giganteum (Wall.) Makino,callose ring was observed at the median section of the MMCs at the prophase of meiosis,and then formed a centripetal cell plate.4.The ultrastructure of pollen wallThe structure and development of pollen wall in A.senescens L.and C.giganteum(Wall.) Makina is studied by electron microscope technique.The relation between the distribution of ubisch body and the formation of extine has also been discussed.Under TEM,the exine of the 2 species can be distinguished into tectum,baculum and footlayer.The exine of C.giganteum(Wall.) Makina is semi-tectate,while A.senescens L.with drumstick-like tectum puncture and uncontinuous pollenkitt on the surface of pollen.Ubisch body originated from rER or mitochondria.There are lots ofubisch body outside the tapetum cells,free microspores,and mature pollen.The ubisch body in A.senescens L.has smooth edge,while it has wavy edge in C.giganteum(Wall.) Makina.What important significance is the taxonomic value ofubisch body in systematic botany needs further study.