Preliminary Studies On The Improvement Of Fiber Color Of Kaiyuan Mumian, A Landrace Of Gossypium Barbadengse In Yunnan

Kaiyuan Mumian（G.barbadense）with good resistance is a native variety belonging to island cotton.It has a large plant with lush green leaves,large and beautiful flowers and lots of fruits,suggesting it has potential ornamental value.It is used as ornament in some ethnic minority areas of Yunnan Province.In order to further increase the ornamental value of Kaiyuan Mumian,three methods including RNA interference,interspecific hybridization and grafting were adopted to diversify the fiber color of Kaiyuan Mumian in this study.The results could provide the foundation for the garden use of Kaiyuan Mumian.The main results are as follows:1.Kaiyuan Mumian with brown fiber was obtained by cross between species:Kaiyuan Mumian as female parent and brown fiber 1 as male parent were hybridized.Then,the interspecific hybrid F₁ generation were obtained.F₁ is like Kaiyuan Mumian in plant shape,flower and leaves.Its fiber is light brown which is between brown of female fiber and white of male fiber.The characters of F₁ can be fixed through vegetative propagation,which enhance the ornamental value of Kaiyuan Mumian.This result showed it is effective to change the fiber color of Kaiyuan Mumian by the interspecific hybridization between Kaiyuan Mumian and colored cotton.2.The grafted seedlings derived of colored cotton and Kaiyuan Mumian were obtained:Kaiyuan Mumian with high and thick stem,and good growth was used as rootstock.Green cotton and brown cotton were used as scion.and the grafting methods including scarf joint and cleft grafting were adopted.The seedlings were grafted and the scion for green cotton and brown cotton were successfully obtained,respectively.These results indicated that the grafting technology to change the fiber color of Kaiyuan Mumian was also an effective way.3.The vectors of RNAi targeting F3’5’H gene were successfully constructed;The plants which contains F3’5’H gene were obtained:The target fragment of F3’5’H gene was transformed into the slightly injured seeds of Kaiyuan Mumian by Agrobacterium-mediated method.:F3’5’H gene is one of key gene in the anthocyanidin synthesis pathway.The specific primers were designed by F3’5’H gene information published on cotton gene database.RNA was extracted from the tender leaves of Kaiyuan Mumian and target fragment of F3’5’H genes were amplified by RT-PCR.After target fragment was confirmed by sequencing,the vectors of RNAi targeting F3’5’H gene were constructed by Gateway technology.The transgenic plants with resistance were detected by PCR.Some plants were positive,suggesting the vector of RNA interference of F3’5’H gene was successfully transferred into the genome of Kaiyuan Mumian.Compared with the controlled group,the plants which were positive have significant differences in growth vigor,leaf shape and leaf color.