Influence of Puroindoline Gene on Milling Performance, Steamed Bread and Noodle Qualities in Spring Wheat Molecular Identification and Analysis of Puroindoline Alleles in 81 Foreign Wheat Varieties Single-kernel Hardnesses and Their Single-kernel Frequencies of Some Winter Wheat Varities in China Influence of Introducing LPAAT and KCS Genes into Rape on Erucic Acid Content of Seed