Submitted to: Crop Science
Publication Type: Review Article
Publication Acceptance Date: 2/3/2009
Publication Date: 6/30/2009
Citation: Jauhar, P.P., Xu, S.S., Baenziger, S. 2009. Haploidy in Cultivated Wheats: Induction and Utility in Basic and Applied Research Crop Science Vol 49:737-754
Technical Abstract: The usefulness of haploid plants in basic research in cytogenetics, genetics, evolution, and in practical plant breeding has been amply documented. Haploids provide an efficient research tool for studies on induced mutagenesis and genetic transformation. They also help elucidate the genetic control of chromosome pairing inherently present in allopolyploids like the bread wheat, durum wheat, and oats. Genetic control of chromosome pairing has, in turn, helped in assessing intergenomic relationships. Moreover, haploids offer a unique opportunity for studying chromosome pairing relationships because the intergenomic homologies, that generally remain masked in the parental species, are best revealed in the chromosome complement in the haploid state. Thus, by studying chromosome pairing in polyhaploids of cultivated wheats – bread wheat and durum wheat (Triticum turgidum L., 2n = 4x = 28) – we have assessed intergenomic relationships. These studies have contributed significantly to our understanding of these wheats. By analyzing the degree and the specificity of chromosome pairing in the Ph1- and ph1b-euhaploids (2n = 3x = 21; ABD), we demonstrated that the A and D genomes are more closely related to one another than either one is to the B genome. In addition to its numerous applications in biological research, the haploidy approach is an integral part of several plant breeding programs. It provides an efficient and rapid means of producing truly homozygous lines, thereby accelerating the breeding process. Therefore, the importance of haploidy-induced instant homozygosity cannot be overemphasized. The haploidy techniques can be fruitfully employed for the genetic improvement of both bread wheat and durum wheat. Methods of inducing haploid plants of these polyploid wheats are described, and the utility and several important aspects of haploidy are discussed in this article.