Dissertation > Agricultural Sciences > Crop > Cereal crops > Buckwheat

Study on Diversity of CHS Gene from Buckwheat Germplasm Resources

Author YangPeng
Tutor LiYanQin;ZhangZongWen
School Shanxi University
Course Biochemistry and Molecular Biology
Keywords Tartary buckwheat seed protein CHS gene SNP markers genetic diversity
CLC S517
Type Master's thesis
Year 2011
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Tartary buckwheat, family polygonaceae, Genus Fagopyrum enjoys a long fame as a functional food rich in flavonoids. The protein content of buckwheat seed is critical for breeding and product quality. Chalcone synthase (CHS) gene is a key gene in the biosynthesis of flavonoids. The diversity of CHS gene directly affects the flavonoid content in buckwheat. In this study, genetic diversity of seed storage proteins and CHS gene diversity in tartary buckwheat was studied, in order to discover tartary buckwheat germplasm with high flavonoids content and provide a basis for association analysis and single nucleotide polymorphism (SNP) marker-assisted breeding.Seed proteins of 166 accessions of tartary buckwheat from 14 different geographical regions were analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to estimate their genetic diversity. Total 21 bands were found, varying in molecular weight from 13.84kDa to 100.75 kDa; among which,7 bands were shared by all the populations and other 14 bands (66.67%) were polymorphic. Shannon’s information index of different geographical groups of tartary buckwheat accessions was 0.4238-0.6931 and the genetic similarity coefficients varied from 0.8376 to 0.9931 with the mean genetic similarity coefficient being 0.9187. Three cluster groups were identified for the accessions of tartary buckwheat based on seed proteins genetic similarity. The clustering results revealed that the genetic diversity of accessions of tartary buckwheat closely associated with their origins. However, the SDS-PAGE of seed proteins might not be suitable to identify tartary buckwheat germplasm due to the lack of sufficient visual bands and difficulties in identifying polymorphism.We obtained full length sequence of CHS gene of Laoya buckwheat from Sichuan Province by genome walking technique and designed primers to obtain 30 CHS gene sequences from 30 buckwheat materials which have different flavonoid content. Totally 98 polymorphic sited were identified in 30 accessions, including 41 SNP and 57 Indel, with the frequencies of one per 79 bp and one per 57 bp respectively. Among these polymorphic sites,80 sites were in noncoding regions, including 38 SNP and 42 Indel, counting for 4.4 times of polymorphic sites of coding regions. The values ofπandθwere both lower in coding regions than in noncoding regions. The results of Tajima’s D statistic and Ka/Ks value indicated that negative selection played a major role in the evolution of CHS gene. Five types of (AT)n were detected in CHS gene sequences. Based on the sequences data of CHS gene, analysis of phylogenetic tree showed that it has a certain relationship with flavonoids content.

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