Study On The Nuclear Gene Of The Origin Of Octoploid Cultivars Of Camellia Reticulata

Camellia reticulata Lindl.(Theaceae),also known as "Yunnan Camellia",was an endemic species in China and the highest plant in the Camellia,which has a magnificent body,large and colorful flowers,various varieties,and high ornamental value.It is the flower of Yunnan Province and Kunming.C.reticulata is an allogeneic hexaploidy.Hexaploid was distributed in most of the southwest and was derived from hybridization between Tetraploid and C.saluenensis.Tetraploid was distributed in the Jinsha River valley and was derived from hybridization between Tetraploid and C.pitardii.Diploid was distributed in Huaping,Yunnan and Yanbian,Sichuan.There were reports of octoploid.But how did the octaploid variety of C.reticulata come into being?The thesis used 15 varieties of C.reticulata,including 6 diploid varieties,2 hexaploid varieties,and 7 octaploid varieties as research materials.The internal transcribed spacer(ITS)sequence,the second lar-gest RNA polymerase subunit(RPB2),and phenylalanine ammonia-lyase(PAL)of C.reticulata and congeneric species were analyzed.Based on the cloning sequence,the genetic relationship between octoploid and diploid varieties was studied.The following results can be drawn:1.The sequences of PAL and RPB2 in octaploid varieties such as C.reticulata ‘Dalicha’ and C.reticulata ‘Tongzimian’,there are specific loci identical to those in C.saluenensis,C.pitardii,and diploid.It has been proven that the parental species of hexaploid are C.saluenensis,C.pitardii,and diploid.2.In the RPB2 sequence of the C.reticulata ‘Honghua Youcha’,there are 26 specific loci that are the same as the C.yunnanensis,and C.reticulata ‘Dalicha’ has 3 specific loci that are the same as the C.mairei.It indicated that the parent species of C.reticulata ‘Honghua Youcha’ and C.reticulata ‘Dalicha’ may also involve C.mairei or C.yunnanensis,it may be a polyploidy between hexaploid and C.mairei or C.yunnanensis.3.The diploid was clustered as an independent species in the southwest region of the Camellia.Diploid is more suitable as a new species,is named Camellia xiana W.Zheng sp.Nov.The new species(C.xiana)was distributed in Huaping,Yunnan province,and Yanbian,Sichuan province,and which was considered as vulnerable species according to IUCN.This study provides a reference for the origin and tracing of the octaploid varieties of C.reticulata.