Reproductive Development In Drynaria Roosii And Changes Of Gametophytes Treated By Sucrose

Drynaria roosii is an epiphytic plant of the Polypodiaceae,and its rhizome can be used as the main source of traditional Chinese medicine.On account of the high medicinal value,Drynaria roosii has acquired the certificate of the second sorts of new medicine issued by the State Drug Administration and been put on production,which results in a sharp rise in market demand.At present,the source of traditional Chinese medicine mainly depends on wild resources.At home and abroad,for the lack of experience in breeding and cultivation,artificial propagation and large-scale production of Drynaria roosii have become the bottleneck of the Chinese medicine Osteopractic goods' commercialization.To ascertain Drynaria asexual propagation,organ morphogenesis,development mechanism and optimal culture conditions is the key to solving the problems of artificial breeding.Futhermore,to carry out researches on Drynaria reproductive development process is particularly important.This paper used Drynaria as experimental materials.With the skills of semi thin sectioning,SEM and TEM,we observed the development of sporangium,sporulation and sexual organ.The results are as follows.Drynaria sporangium originates from the cells of leaf surface.After eight oblique divisions,it develops into a sporangium primordium with the apical cell.Mantle cells undergo anticlinal division and develop into sporangium wall after periclinal division of apical cells.The triangle internal cells will develop into tapetum and spores.Drynaria homospore has monolete and different sizes of granular spore ornamentations on the surface.It is the first time to observe the fern spore germination pattern by SEM in this paper,the growth point of the prothallus is composed of rectangular cells,and the cells in the ribs of the mature primary leaves are significantly larger than those in the two wings.During the development of gametophytes,there are many trichomes in ventral prothallus and short rodlike edge.The shape of gametophyte ventral is short rodlike in majority,and trichomes of acupuncture by accident.Rhizoids are borned in the base of the gametophyte with single cell tubular structure,and have the phenomenon of base swelling and end bifurcation.Drynaria gametophyte is hermaphrodite,the antheridium is near the center of the ribs.In mature antheridium,spermatogonia undergo mitosis to form spermatocytes.Then,it becomes the spiral sperm cell of high degree screw after highly concentrated of nucleus.A Drynaria sperm has the flagellums with clockwise rotation.Zoosperms possess the same structure with fern,Ceratopteris thalictroides,Onoclea sensibilis,Asplenium trichomanes,Scolopendrium and so on.The archegonium is mainly located in the middle ribs near the notch with 5-6 layer of neck wall cells.There is a central cell,a ventral groove cell and a neck canal cells with double nucleus in archegonium.A double layer of egg membrane outside the mature egg cell is formed by the accumulation of starved particles.Under the help of water,the sperm enters into the egg cell through the fertilization pore to form a zygote.Researchers have made some study on influencing factors for the development of fern gametophytes,but the effect of sucrose have not been reported.In this study,we set 7 different sucrose concentrations of 0%(control group),0.5%,1%,1.5%,2%,2.5%,3%,control,and recorded the functions of sucrose on the gametophyte development process.The results showed that the sucrose had obvious promoting effect on spore germination and sexual organ formation of Drynaria roosii,the spore germination rate was the highest at the sucrose concentration of 2.5%,and the number of antheridium and archegonia reached the maximum value at the sucrose concentration of 2.5% and 1%,respectively.There was no significant change in the number of asexual gametophytes in the process of aseptic culture,but the number of male gametophyte was significantly increased.In summary,from the view of Drynaria roosii developmental biology,we studied the reproductive process and the effects of sugar on the gametophyte development.The results offer the basic information for in-depth study of the plant sexual reproduction evolution mechanism,and provide technical support for solving the bottleneck problem of Drynaria roosii artificial breeding.