Abstract: 【Objective】Grain hardness, controlled by a hardness (Ha) gene, serves as a basis for classification and marketing of common wheat (Triticum aestivum L.) quality and has a profound effect on milling and end-use quality. CIMMYT is one of the most important places that regularly offer germplasm to Chinese wheat breeding program. This study can provide useful information to introduce wheat to China. 【Method】 A total of 236 wheat lines from CIMMYT crossing program, including common wheat cultivars and advanced lines derived from synthetic hexaploid wheat × common wheat crosses, are used to detect variation of puroindoline alleles by specific-primers PCR amplification and modified SDS-PAGE. PSI (particle size index) hardness was also measured for 160 genotypes. 【Result】 Results indicated that 165 hard wheat lines are Pina-D1b types and the remaining 37 are Pinb-D1b types, which are non-CIMMYT cultivars or their pedigrees contain non-CIMMYT cultivars. Pina-D1j/Pinb-D1i, Pina-D1c/Pinb-D1h, Pina-D1a-Pinb-D1i, Pina-D1a-Pinb-D1j, and wild type (Pina-D1a/Pinb-D1a) are present in 34 soft types. Genotypes with Pina-D1b are significantly harder (lower PSI hardness) than genotypes with Pinb-D1b. Genotypes with Pina-D1c/Pinb-D1h and Pina-D1a/Pinb-D1i are significant harder (lower PSI hardness) than genotypes with Pina-D1j/Pinb-D1i and Pina-D1a/Pinb-D1a. In addition, both Pinb-D1h and Pinb-D1i encode the same polypeptides and a tryptophan substitute (arginine) at position 28, which is the major reason for soft endosperm. In comparison with wild type (Pina-D1a/Pinb-D1a), no change was found in close to tryptophan-rich domain of puroindoline in other soft genotypes except for Pinb-D1h and Pinb-D1i, which may be the main reason that mutation types still remain soft endosperm. 【Conclusion】 It is concluded that all of Pinb-D1b types are non-CIMMYT cultivars or their pedigrees contain non-CIMMYT cultivars and PSI of puroindoline alleles from Ae.tauschii are difference.

Key words: Common wheat, Synthetic wheat, Puroindoline allele, PSI hardness