| Sustainable agriculture requires rapidly breeding new varieties, and conventional breeding methods have been unable to meet the needs of people living and production because of the long cycle. Shortening the breeding cycle to quickly cultivate new varieties have been the direction of breeders’ efforts. Flowering Locus T(FT) and homologous genes play an important role in the flowers developmental and transition process, and promot a conservative function of early flowering in plants.In this study,taking the model plant tobacco as research object,the target traits rapid transfer and sterile lines quickly creating technology research were performed,combined with early flowering cause by exogenous FT gene.Our purpose was to solve the long breeding cycle of conventional backcross breeding,to explore the way of shortening crop breeding cycle.Major progress was made in this research are presented below.1. This research has established tobacco rapid backcross breeding technology mediated by FT gene.There are two core characteristics in this technology.(1)Creating and identifing the single copy FT gene tobacco plants as nonrecurrent parent to comduct the backcross study.(2)In the final backcross generation,FT gene could be successfully separated off to obtain normal flower innovation germplasm. This method could shorten the breeding period,but have no affect on innovation germplasm traits.2.FT gene was cloned by RT-PCR from Arabidopsis,and the construction expression vector FT-P22 was obtained,then introduced into Fc8 and Coker371 gold tobacco genome by Agrobacterium-mediated transfer. And we had got two varieties positive plants with single copy of the FT gene,laiding the germplasm materia lsfoundation for subsequent research of rapidly backcross improved and create sterile lines.Early flower plants generally bloomed when the leaf number was 3 to 4. The FT positive plants’ leaf number decrease 15 to 16 pieces on average,their average plant hight reduce 90 cm, and their budding time is ahead of about 80 days.3.According to the designed rapid backcross breeding technology,on the basis of TMV resistance and molecular marker,using the single copy of early plant with TMV resistance as male parent,backcrss with recurrent parent zhongyan100 which have no TMV resistance to verify the feasibility of the technology of backcross.In cross and backcross generations,early flowering plants with TMV resistance were chosen to self continuously.In the final backcross generation,early flowering plants with TMV resistance were chosen to self,and In the selfing separation,not early flowing plants with TMV resistance were chosen to self continuly for screening plants having homozygous target characteristic. After identifing contained no promoter,terminator,selection marker gene and FT gene,those plants could be used as germplasm innovation.This study can provide rapidly backcross breeding method for the whole plant breeding.Now we had back-crossed the BC4F1.FT gene was able to stably express in backcross generations, greatly reducing the breeding cycle.We also obtained the new BC1、BC2、BC3 germination with TMV resistance.4.According to the designed rapidly creating sterile lines,using the single copy of early plant Coker371 gold as male parent,cross with conventional sterile lines Fc8.In the offspring,early flowering plants were chosen to backcross with recurrent parent fertile Fc8 for many times.Finally,we got the plants agronomic traits were consistent with conventional sterility plant Fc8.The sterile lines fast cultivation system was established. |
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