| Currently, there is considerable interest in the use of spelt (Triticum spelta. L.) for food destined for health and organic food markets. Spelt is an ancient cereal that was once cultivated extensively and is now receiving a renewal interest for its nutritional qualities and, from an agronomic point of view, for its resistance to pests and its ability to grow in soils with limited fertility and in wet and cold climates where it is better than weat. T. spelta, with many useful genes for wheat improvement, is the primary gene pool of bread wheat and easy to be utilized in wheat improvement. Thus, it is important to evaluate the germplasm of spelt wheat. In this paper, the population genetic diversity was estimated based on agronomic traits, quality characters, biochemical and molecular markers. The following results were obtained.1. The agronomic traits of 151 spelt wheat accessions collected from 18 countries and areas, were investigated based on the correlation, principal component and cluster analysis. Higher variations of the agronomic traits were observed. The spelt wheat investigated in this study had the beneficial traits of more tillers and spikelet per spike, and disadvantage of higher plant height, lower 1000-grains weight and longer growing periods. The correlation analysis indicated that the spike number per plant limited the production of spelt wheat. By clustering analysis, all accessions were divided into four groups, and the genetic distances based on agronomic traits were associated with their geographic distribution. Based on principle elements analysis, five principle elements were obtained, which contributes the variance over 85%. According to these main characters, tweenty-two accessions with one or some elite agronomic performances were screen out.2. The analysis of quality characters showed that most of spelt kernels were soft and dextrous. Comprared with common wheat, spelt wheat had higher protein content, wet gluten, gluten index and sedimentation values. As rheologic traits were concerned, spelt wheat had higher water absorption and longer development time, whereas spelt wheat showed shorter stable time. Spelt wheat had lower starch content, weaker extension and lower loaf volume. According to these quality characters, all the materials were divided into four groups by clustering analysis. Six accessions with elite agronomic and quality characters were selected for the utilization in wheat improvment.3. Gliadin and HMW glutenin subunit variations in 162 spelt wheat accessions were detected by A-PAGE and SDS-PAGE. Higher gliadin variation was observed, and 121 gliadin patterns were detected. A total of 9 HMW-GS alleles were found. There were 2, 5 and 2 alleles at Glu-A1, Glu-B1 and Glu-D1 loci, respectively, resulting in 8 HMW-GS combinations. The HMW-GS combination (1, 6+8, 2+12) was the dominant phenotype, which was found in 83.00% accessions. These results suggested that the polymorphism of spelt wheat on Gli-1 loci was higher than that on Glu-1 loci.4. To get more information onα-gliadin genes of spelt wheat, specific PCR primers were designed based on the known wheatα-gliadin gene sequences, and the coding regions of two gliadin genes Gli-Spelt-1 and Gli-Spelt-2 were isolated from spelt wheat NGB5149. Gli-Spelt-1 was a pseudogene due to the stop codons in its coding region. The full coding region of Spelt-Gli-2 was 849bp, and could be translated into a protein of 263 amino acids. The two cloned gliadin genes had the typical structure ofα-gliadin genes. The deduced amino acid sequences comparison suggested that Spelt-Gli-2 had the high identity with the knownα-gliadin genes.5. ADP-ribosylation factors (ARFs), a subfamily of the small GTP binding proteins superfamily, are believed to participate in vesicular transport and signal transduction events in the cell. The DNA sequences included four exons and three introns. Its deduced amino acid sequence had consensus with GTP-binding domain P (GLDAAGKT), G'(DVGGQ) and G (NKQD). Moreover, in two ends of introns of ARF gene from diploid species, common wheat and spelt wheat, there were new base sequences which did not comply with typical GU-AG rule. We speculated that these new base sequences might have relation to a new splice process. To assign the chromosomal locations of ARF genes in common wheat, 20 specific primer sets were designed on the specific SNPs, and PCR assay of the genomic DNAs of Chinese Spring ditelosomic lines were carried out. The ARF genes were located on the chromosomes 2AL and 3DL. ARF transcripts were detected mainly in root and immature embryo.6. High heterosis was obtained in the hybrids between common wheat and spelt wheat. The yield per plant, grains weight per spike and 1000 grain weight had higher heterosis. The heading dates of interspecific hybrids were 0 to 6 days later than female parents (common wheat) and 20 days earlier than male parents (spelt wheat). The analysis the quality characters showed that the the performance of quality characters in interspecific hybrids were superior to the female parents (common wheat), indicating that interspecific hybrids are very useful and efficient for the improvement of bread wheat by exploiting desirable genes in spelt wheat.
|
PDF Full Text Request