Yan Ze-hong

Genetic diversity among the germplasm resources of the genus Houttuynia Thunb. in China based on RAMP markers

The genetic diversity of 70 Houttuynia Thunb. accessions from Sichuan, Chongqing, Guizhou and Jiangsu province in China were tested by using random amplified microsatellite polymorphism (RAMP) markers. All of the 43 primer combinations were found to amplify polymorphic products. A total of 304 products were amplified. Of which, 97.7 products were polymorphic. 6.9 polymorphic bands were amplified by each primer combination on average. The genetic similarity (GS) between the accessions within H. emeiensis and H. cordata were 0.660 and 0.575, respectively. The GS between two species was 0.525. The GS values between H. emeiensis and the H. cordata cytotype with the chromosome number of 36 was 0.559, higher than that between H. emeiensis and the cytotypes of H. cordata with other chromosome numbers. Within the species H. cordata, the genetic variation between cultivated and wild accessions was insignificant. The results of cluster analysis by using UPGMA method showed that all the tested accessions could be differentiated by RAMP markers, and classified into 11 groups. Many accessions with the same chromosome numbers could be classified together. The genetic diversity was more plentiful in mountainous and margin areas of the Sichuan Basin than at the bottom of the Basin and the highlands or hills surrounding it. It was concluded that there existed higher genetic diversity at the molecular level (RAMP markers) among the germplasm resources of the genus Houttuynia. The genetic relationships and phylogeny of the germplasm resources of Houttuynia were also discussed.

Characterization of a Novel 1Ay Gene and Its Expression Protein in Triticum urartu

High molecular weight glutenin subunit (HMW-GS) plays an important role in determining dough property and bread-making quality, and the exploration of novel genes for HMW-GS will be crucial for quality improvement program. A gene coding the y type HMW-GS at Glu-A1 locus in Triticum urartu (AA, 2n = 2x = 14) with an electrophoretic mobility similar to that of 1Dy12, was cloned, sequenced, and heterologously expressed. This novel active 1 Ay gene FJ404595 was confirmed by structure analyses of nucleotide and deduced amino acid sequences combining with phylogenetic analysis. The open reading frame (ORF) of this gene was 1 830 bp, encoded a protein of 608 amino acid residues containing 46 hexapeptides and 14 nonapeptides, which was mostly similar to the 1 Ay gene AM183223 at a high identity of 99.62% with the two substitutions of both leucine/proline and valine/glutamate, obviously different from the I Ay gene EU984504 with 587 residues containing 44 hexapeptides and 13 nonapeptides in T. urartu. The amino acid (leucine) at 446 differed from that (proline) of all the eight compared active 1Ay subunits. The predicted secondary protein structure implied that this 1Ay subunit might also have positive impact on flour processing quality.

Analysis and validation of genome-specific DNA variations in 5′ flanking conserved sequences of wheat low-molecular-weight glutenin subunit genes

The thirty-three 5′ flanking conserved sequences of the known low-molecular-weight subunit (LMW-GS) genes have been divided into eight clusters, which was in agreement with the classification based on the deduced N-terminal protein sequences. The DNA polymorphism between the eight clusters was obtained by sequence alignment, and a total of 34 polymorphic positions were observed in the approximately 200 bp regions, among which 18 polymorphic positions were candidate SNPs. Seven cluster-specific primer sets were designed for seven out of eight clusters containing cluster-specific bases, with which the genomic DNA of the ditelosomic lines of group 1 chromosomes of a wheat variety ‘Chinese Spring’ was employed to carry out chromosome assignment. The subsequent cloning and DNA sequencing of PCR fragments validated the sequences specificity of the 5′ flanking conserved sequences between LMW-GS gene groups in different genomes. These results suggested that the coding and 5′ flanking regions of LMW-GS genes are likely to have evolved in a concerted fashion. The seven primer sets developed in this study could be used to isolate the complete ORFs of seven groups of LMW-GS genes, respectively, and therefore possess great value for further research in the contributions of a single LMW-GS gene to wheat quality in the complex genetic background and the efficient selections of quality-related components in breeding programs.