The Physical Locations Of Some Genes Involved In Starch Synthesis And Metabolism In Manihot Esculenta Crantz

Cassava(Manihot esculenta Crantz)is one of the most important food and energy crops in tropical regions.As root rich in starch,cassava is one of the important sources of industrial alcohol.Starch branching enzyme(SBE)and Granule bound starch synthase(GBSS)genes are key enzymes of starch synthesis processes in cassava.Neutral/alkaline invertase(MeNINVl,nINVl)and hexokinase(MeHXK2)are key enzymes of starch metabolism processes in cassava.The genes which express these enzymes have been cloned by predecessors,but their physical locations on chromosome have not been reported.We took cassava(SC6)root(2 n = 36)as material for cell chromosome specimen preparation.Fluorescence in situ hybridization technology(FISH)was used to locate GBSS,SBEI,MeNINV1,nINVl and MeHXK2 genes.The research results are as follows:(1)In this study,we made improvement on key operations in FISH,such as pretreatment of material,pretreatment of chromosome specimens and elution of chromosome specimens after hybridization.(2)Single-colour FISH was used to identify the physical location of MeNINVl,nINVl and MeHXK2.The GBSSI gene was located on the short arm of chromosome 13,the percentage distance from centromere to signal was about 26.3± 0.1;MeNINVl gene was located on the short arm of chromosome 11,the percentage distance from centromere to signal was about 40.1 ± 0.3;MeHXK2 gene was located on the short arm of chromosome 12,the percentage distance from centromere to signal was 21.0±0.2,and further research was necessary to locate nINVl gene.(3)Double-colour FISH was used to locate GBSSII gene which on the short arm of chromosome 11,the percentage distance fron centromere to signal was 14.0 ± 0.5.SBEI gene located on the long arm of chromosome 12,the percentage distance fron centromere to signal was 76.2±0.2.(4)Linkage analysis reseach was conducted among the five located genes,The results showed that both GBSSII gene and MeNINVl gene were located on the short arm of chromosome 11.They are linkage genes.SBEI gene and MeHXK2 gene were located on the long arm and short arm of chromosome 12,respectively.They are also linkage genes.