Study On Floral Organogenesis And Dynamic Changes Of Endogenous Hormones Of Eurya Loquaiana Dunn

Eurya Thunb.belong to Theaceae,which is a new genus species created by Thunberg(1783)based on the E.japonica Thunb.from Japanese.There is still a lot of controversy about research of Eurya systematics accompanied by the process of continuous improvement.Gender variation is a significant phenomenon found in recent studies in Eurya A simple fact is that Eurya is dioecious,but relevant survey shows that Eurya populations of bisexual flowers is a common phenomenon.Presently,Most study about E.focus on its classical taxonomy.With Eurya loquaiana Dunn female and male strain and gender variant plants,the process of floral organogenesis were observed,and the dynamic of endogenous hormone level of leaves in several key periods during flower development was determined for comparative analysis.Thus to explore the similarities and differences of floral organogenesis of different gender and the effect of different hormones in the sex differentiation of Eurya.Conclusions are as follows:(1)According to the characteristics of floral organs,from the initial stage of flower bud differentiation,the prosess of floral development can be divided into four stages: Bract differentiation stage,sepal differentiation stage,petal differentiation stage,stamen and pistil differentiation stage,of which the occurrence of bracts and tepals is consistent with corresponding stage of Ternstroemoideae.The floral organs usually have 2 bracts,5 sepals and 5 petals,and the tepals are all in the direction of the 2 / 5 helices.Sepals and petals are homologous,which can be seen from the characteristics of the early development of floral organ.From the spiral tepals primordial and imbricate arrangement of mature perianth segments,It can be deduced that Eurya is relatively primitive groups which is deviated from the point that unisexual flower has a higher degree of evolution than hermaphrodite flower.(2)Unstability can be seen in the early period of floral development,which is contrary to the general view that the expression of genetic characteristics is stable in biological evolution of biological entity during early development.Conclusions are as follows:a.Ovary development of Eurya pistillate flowers are basically 3 carpel primordia formed at the same time,then developed into 3 hemispherical bulges respectively,eventually healed into ovary(with a few 2 carpel development phenomenon.),The placenta developed from the base of carpels and eventually developed into the typical axile type.b.Stamen primordia and pistil primordial appear in male flower at the same time,of which the latter stops dividing at certain stage during early development,while the fomer continues normal development.The stamen primordium did not form a circular primordium,and it did not occur synchronously in the primordium.Finally,it reached the same size at maturity,8-16 pieces.In mature male flowers,there are obvious abortive pistils.c.The occurrence of pistil and stamen primordia of Eurya gender variant is same as the above-mentioned two.but,on the same plant,a high uncertainty can be seen in the position and number of stamen primordial(uncertain,about 0-16),some of which are abnormal(stamen abortion);The development of pistil is also different from that of female flowers,and the development of the 2 carpel primordia into ovary is more common.d.From a single flower level,there are several types of gender variant flowers: normal female,normal male with pistillode,normal female with abortive stamens,normal bisexual flowers(stamen number ranging from 1-16).(3)From the single hormone level,the effect of GA3 content on stamen development was relatively obvious.The content of IAA was relatively stable in the development stage of female flower bud to the pistil primordium,but increased obviously during the development of pistil primordium;The IAA content of male and female mutant strains remained stable.The content of IAA has a promoting effect on the development of female flower bud differentiation process of Eurya.The content of ABA in female plants showed a steady downward trend,while the ABA content of male plants was the opposite,The content of ABA in the sex variant strains was between the female and male plants,accordingly the content of ABA would promot the development of stamen,but not to the development of pistil.In terms of the ZR content level,its changes in Eurya male plant was relatively significant.(4)From the balance of hormone level,ABA / ZR ratio has obvious effect on promoting the Eurya stamen development and influence on female plants,gender variant plants are relatively weak.From the variation of the ratio of GA3 / ABA in male and variant strains,it may not be beneficial to the pistil development of male and gender variant plants.The ratio of ZR / GA3 and IAA / ABA was increased in female plants,while the proportion of male and variant strains was relatively stable,so it may promote the development of pistil.The ratio of IAA / GA3 in male plants showed a significant upward trend,and the IAA / GA3 content ratio of male plant is higher than that of female and gender variant in the whole development process.therefore,the IAA / GA3 content ratio is conducive to the development of stamens.The hormone levels of sex variant strains were basically between female and male plants,according to the hormonal balance hypothesis,it is possible that the regulation of hormone levels leads to the development of the same flower to two directions of stamen and pistil development.In summary,by SEM(scanning electron microscope)and paraffin section method,morphological features of different stages of the development of Eurya floral organ was observed and compared with that of closely related taxa,thus to provide morphological evidence for further study of the systematic status of Eurya and Ternstroemioideae of each genus.At the same time,by determining the content of 4 important endogenous hormones(GA3,IAA,ABA,ZR)in the critical period of Eurya during flower buds development,thus to investigate the role of endogenous hormone content and the proportion of two of them on Eurya sex expression.The most important of all,to provide a theoretical basis for further research on the phenomenon of gender variation of Eurya plants within the groups,which can also be scientific data supplement to reveal the long process of plant system evolution.