| Germplasm is the carrier of gene, the material basis of wheat genetic improvement, animportant source of the parents, but also material basis to to carry out basic biologicalresearch. It is an effective way to improve the quality, disease resistance and stress toleranceof Chinese wheat by introducing foreign excellent wheat germplasms. America, as animportant producer of wheat in the world, with complex geographical and climaticcharacteristics and rich germplasm resources, had collected and used the wheat germplasmresources worldwide, particularly in good quality resources and resilience resources, whichhad obvious advantages compared to China. In this study, the agronomic traits of350wheataccessions introduced from America were firstly investigated to screen out the ones whoadapted to the ecological conditions of Huang-huai wheat areas and finally67wheat varietiesmeeted the reqirements. And then a series of further analysis such as agronomic traits, qualityparameters, the composition of HMW-GS and SSR molecular markers were carried out tostudy the genetic diversity of these67wheat accessions. The main results are as follows:Phenotype characteristics and adult-plant stage disease resistance of67American wheataccessions were analyzed and evaluated. The results showed that most of these materials werelate-maturing, winterness, lighter with1000-grain weight and higher with plant height. Mostgrains were plump and hard and some excellent agronomical traits were discovered. Theresistance to different races of stripe rust was tested at adult stage.23accessions (34.33%)appeared resistant to CYR32, CYR33and moderately resistant to mixed races.6accessions(8.96%) appeared immune to CYR32, CYR33and mixed races respectively,indicating that they had race non-specific resistance to currently prevalent stripe rust races.The resistance to natural mixed races of powdery mildew showed that17accessions(25.37%)appeared resistant to currently prevalent powdery mildew races. The resistance to naturalmixed races of head blight showed that there were only28(41.79%) accessions appearedmoderately resistance.17accessions with stronger resistance to two or three kinds of disease were screened out, and they may make significant contribution to disease resistance breeding.SDS-PAGE were used to detect HMW-GS compositions and the results showed thatthere were20types of subunits and25types of subunit combinations, meaning that Glu-1locus had a high level of variations. There were three unfrequent and three unknown subunitslocated on Glu-B1loci, and one unknown subunit maybe located on Glu-D1loci. The meanquality score were8.15, and forty one accessions scored above8(including8), and even8accessions had a score of10. Seven quality indexes of67American wheat accessions and14accessions with good quality or large scale planted accessions of China were analyzed byDA7200near-infrared composition analyzer. Compared with Chinese wheat accessions, theseAmerican materials showed lower quality indexes. Three American varieties were screenedout with both comprehensive better flour quality and good quality HMW-GS.Fifty-five primers tested which were located on different wheat chromosome arms, wereused to analyze the genetic diversity of67wheat accessions introduced from America and17accessions from China as contrasts. The results showed that mean allele number of Americanwheat accessions was8.10, and the average polymorphic information content (PIC) was0.59.The Corresponding value of Chinese wheat accessions were4.84and0.55. Clusteringanalysis showed that55primer pairs could separate the84accessions into six groups. Theresults suggest that the American wheat accessions have higher genetic diversity than Chinesewheat accessions. |
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