Under those circumstances, the Managing Editor and Secretary asked the Editorial Board of WIS to discuss whether we should continue its publication or not. The Board reached an agreement that publication of WIS in the present form should be discontinued with the 100th issue and that this last issue should be published in a special form to celebrate the memory of the 52 years' history of WIS. The Editorial Board asked the members of the International Advisory Board of WIS for their opinion on the above agreement, and found that it was supported by most members. The discontinuation of WIS publication was announced by the Secretary (T. Sasakuma) at the business meeting of the 10th International Wheat Genetics Sympoium held at Paestum, Italy, September, 2003.

The Editorial Board discussed the outline of the memorial issue and appointed me to take responsibility for editing this particular issue. I, as the editor of the memorial issue, considered this matter and came to the view that we should utilize this publication for encouraging young wheat researchers, rather than for presenting summarized accounts of the contemporary work in the fields of wheat genetics and breeding. This is because encouragement of the young generation is of the prime importance for the future rigorous development of any scientific field. Based on this thought, I developed my idea (outlined below) for editing the 100th memorial issue in July, 2004, and it was approved later by the Editorial Board:
1) To publish the issue as a separate book of about 200 pages, with a tentative title 'Frontiers of Wheat Bioscience", by the end of 2005, succeeding the publication of the 99th issue, which was scheduled at that time in March, 2005.
2) To ask contribution of an original article each from about a dozen wheat researchers who are expected to play key roles in the development of wheat genetics and breeding in the coming decades.
3) To select contributors from diverse fields of wheat genetics and breeding.

I asked 12 foreign and 12 Japanese recognized wheat scientists for recommendations of qualified contributors, whom they considered a key person for the future development of wheat genetics and breeding. Of the candidates recommended by them, I selected 18 persons, to whom I sent an invitation letter in October, 2004, asking for their kind contribution to the memorial issue. Sixteen of them generously accepted the invitation and their manuscripts were received by the due date.

The main part of the editorial works of the book was carried out by K. Furukawa, a secretary of the Kihara Memorial Yokohama Foundation, with the support of two WIS secretaries, T. Sasakuma and H. Tsujimoto, in different aspects of the editing. I received essential advice from K. Nishikawa, the present Managing Editor of WIS, on my editorial work. The Kihara Memorial Yokohama Foundation covered most of the publication cost. The collaboration and contribution of all those persons and the Foundation facilitated the publication of the present book at the scheduled time. As the editor of this book, I would like to express my cordial appreciation to all of them.

Modern wheat genetics has been founded on four corner-stones; the discovery of polyploidy in wheat, by T. Sakamura (1918), the completion of genome analysis and elucidation of the genome-based species relationship in the wheat complex (Triticum and Aegilops), by H. Kihara (1924 to 1962), the production of various aneuploid series, namely, nullisomic, monosomic, trisomic, tetrasomic, nulli-tetrasomic and ditelosomic series, leading to the concept of chromosome and gene homoeology, by E. R. Sears (1954 to 1978), and the discovery of the Ph gene and its suppressor, enabling elucidation of the mechanism of cytological diploidlization in polyploid wheats, by R. Riley (1958-1963).

On those firm bases, wheat genetics and breeding have achieved remarkable progress in the last 50 years. During this period, chromosome engineering, a branch of cytogenetics, has reached its climax in wheat owing to the availability of various aueuploid series and discovery of the gene system for suppression and promotion of the homoeologous chromosome pairing. In wheat cytogenetics, a new wave of molecular cytogenetics occurred in the mid 1970's and its progress was enhanced by the recent developments in DNA technology. Individual genomes, chromosomes, gene clusters and even genes are now visually identified under the microscope. Gene locations confirmed by eye in condensed chromosomes and even in relaxed DNA fibers provide indispensable information for genetic analysis and molecular breeding. Another new development, namely the flow cytometry of chromosomes, made mass fractionation of specific chromosomes or chromosome arms possible. Aneuploid series such as the telocentrics and chromosome terminal deletion lines produced by gametocidal genes facilitate the fractionation of all chromosome arms or fragments, providing reliable DNA sources for future wheat genome projects. Four articles on those topics are presented in Part I of this book under the heading, "Frontiers of Wheat Cytogenetics".

The new field of wheat genetics that has predominated from the 1980's onward is molecular genetics. Developments in this field consist of two different but mutually related streams. One stream aims at clarification of the genetic processes that control important functions related to wheat physiology, morphogenesis, production and evolution. The recent trend is application of the methods of reverse genetics, namely, isolation and sequencing of the responsible candidate genes (DNAs), followed by demonstration of the expression of their expected functions in various forms of transformants. Six articles compiled in Part II, "Dynamic Functions: Biosynthesis to Morphogenesis", deal with diverse topics along this stream, such as grain physiology, cold acclimation, growth phase transition, and gross ear morphology.

The other stream ultimately alms at elucidation of the entire genome structure and function. This stream started with restriction fragment length polymorphism (RFLP) analysis of the repeated DNAs, followed by analyses of different kinds of DNA polymorphisms, such as RAPD (randomly amplified polymorphic DNA) and SNP (single nucleotide polymorphism). Mapping of those molecular markers led to construction of high density molecular marker maps of all 21 wheat chromosomes. The maps are utilized in mapping and isolating wheat genes for important quantitative as well as qualitative characters. The above two lines of work are integrated into the unified field of wheat genomics. The first three articles in Part III "From Genomics to Molecular Breeding" represent current achievements of wheat genomics, having within the scope their utilization in future wheat breeding.

Progress in wheat breeding during this period has also been tremendous. The first monumental achievement was the "Green Revolution" pioneered by 0. A. Vogel and symbolically crystalized as a Nobel Prize received by N. E. Borlaug. Seen from the genetic point of view, the achievement owed much to the Norin 10 semi-dwarfing genes. Triticale and hybrid wheat were forerunners in wheat breeding during the mean-time. Success in breeding high-yielding cultivars using the 1BL-1RS translocation was another monumental achievement. Supported by recent developments in wheat genomics, molecular breeding has entered a new area. Many genes, including QTL loci, of agronomic importance have been successfully identified and/or isolated, although lack of an efficient transformation system in wheat still remains a serious bottleneck. The last three articles in Part III of this book describe genetic resources usable for future wheat molecular breeding and its strategies.

Each article has a comprehensive reference list at the end and, in addition, an index has been prepared to help cross-checking of respective items across the related articles. Those features, together with the newest information presented on the subject of each article, will make this book useful reading material for advanced students as well as researchers who have a keen interest in the recent progress in wheat genetics and breeding.