Study Of Strobilus Differentiation And Development In Pinus Massoniana “polycone”

"Polycone" is a special phenomenon of Pinus massoniana plants. On the female procreation branch of the multiple cone type Pinus massoniana,it can produce several tens to hundreds cones(megastrobilus). However, the naturally fertilization rate of these cones was low, and their seed setting rate was poor.The causes were still lack of systematic study.In this paper,Pinus massoniana with polycone in Duyun Mazhai Pinus massoniana Breeding Base Gene Collection Zone was used as research object.And the strobilus differentiation and development were studied through anatomy,embryology,nutrition material,and analysis of Hormone metabolism.The strobilus differentiation and development process of Pinus massoniana polycone was understand and the regulatory mechanism of flower bud differentiation and development of "polycone" Pinus massoniana was analyzed.The reason why the the naturally fertilization rate of polycone is low,and their seed rate is poor was discussed,which provides a theoretical basis for reproductive regulation.The main research work and achievements are as follow:(1)The megastrobilus development of Pinus massoniana normal cones was mainly divided into 5 distinct stages:during buld storage periodin early August,the occurrence of female cone primordial in the end of September,the bract primordium has been initiated in early November,the ovuliferous scale primordium has been initiated in mid-December and the ovule differentiation stage in mid-March in last year.(2)By the end of August,the Pinus massoniana microstrobilus borne by the string-like reproductive bud primordia in buds base development.In mid-September,the minor sporangium-like structure appeared. At end of October to early November,the occurrence of long string-like microstrobilus primordial.At the end of March next year,microsporangium have matured.At early April,the male cones started shedding.About April 10 th,the loose ended and after shedding,the male cones fall off immediately.(3)By comparison,the two different development processes of Pinus massoniana polycone phenomenon was clear.One of them is appearing during the process of Masson Pine strobilus differentiation in the August,synchronized with the normal development of microstrobil starting time.Until the end of December,the birth of buds in the same year have a string-like reproductive bud primordia not only with obviously microstrobilus primordia,simultaneously with megastrobilus characteristic cone scales primordium bud scales and structures,some of which in the base of the terminal bud shaped growth clusters megastrobilus primordium. The other is in the process of male cones development occurring sex reversal,those buds in the form of microstrobilus to differentiation and development to the mid March of the next year.All multi-cone buds grow male cone flower buds whose bud scales open fully to mid-March,with the revealing of male cones.In the following ten days,pollen sacs from the top to the base vary the bracts of female cones and cone scales,and gradually the appearance of pollen sacs completely transform to female cones.Until the end of March,microstrobilus entire into unusual megastrobilus megastrobilus,and the female cones of multiple cones have formed.(4)The female strobilis abortion of Pinus massoniana polycone occur mainly in the stage of female gametophyte development. In mid April of the pollination year, a large number of free nuclei in female gamete multiple cone type within the ovules begin to decrease,and the core of ovules gradually becomes empty.To early May,the free nuclear of normal ovules begin to cellularization, and the free nuclear of sterile ovules in polycone female gametophyte disappear,thus only the cavity is visible.(5)In the process of strobilus differentiation and development of Pinus massoniana,the content of soluble sugar, starch and soluble protein in the branches of polycone(the branches of polycone in Pinus massoniana polycone)、the single cones branches(the branches of normal cones in Pinus massoniana polycone) and control(the reproductive branch in Pinus massoniana normal cones),were significantly changed.Compared with the single cones branches and control,the content in the branches of polycone had great significant difference.(6)In the process of strobilus differentiation and development of Pinus massoniana,except ZR,other endogenous hormone content in the buds of polycone had significant difference with the single cones buds and control.(7)In the process of strobilus differentiation and development of Pinusmassoniana,POD and IAAO activity were changed significantly.Compared with the POD,the activity of IAAO changed more pronounced.And in more periodsa.The POD and IAAO activity in the branches of polycone had significant difference with the single cones branches and control.