|Ceoloni, Carla - AGRIBIOL, U OF TUSCIA IT|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 15, 2004
Publication Date: December 15, 2005
Citation: Ceoloni, C., Jauhar, P.P. 2005. Chromosome engineering of the durum wheat genome: strategies and applications of potential breeding value. book chapter in "Genetic Resources, Chromosome Engineering and Crop Improvement 2:27-59. CRC Press, Boca Raton, FL. Interpretive Summary: Genetic improvement of wheat has been mostly achieved by conventional breeding, sometimes combined with sexual hybridization with related species. These procedures have resulted in durum cultivars with high yields and other superior agronomic traits such as grain quality. Some desirable genes, such as those for resistance to various diseases, have been incorporated by crossing an appropriate alien donor with a crop cultivar. In such cases, lack of pairing between wheat and alien chromosomes may impede the desired gene transfers necessitating an appropriate manipulation of chromosome pairing. However, these procedures are lengthy and often tedious. Moreover, in some cases sexual hybrids cannot be obtained because of insurmountable crossability barriers. The development of novel gene-transfer techniques that allow direct delivery of a desired gene into an otherwise superior durum cultivar has added new dimensions to genetic improvement programs. In this article, we mainly describe durum improvement by chromosome engineering (wide hybridization coupled with manipulation of chromosome pairing) as well as by tools of genetic engineering (direct gene transfer). We believe that an appropriate combination of traditional and modern techniques will help accelerate durum improvement.
Technical Abstract: Durum or macaroni wheat (Triticum turgidum, 2n = 4x = 28; AABB genomes) - a forerunner of bread wheat, Triticum aestivum L. (2n = 6x = 42; AABBDD genomes) - is an important cereal crop used for human consumption worldwide. Because of its high protein content and gluten strength it is the choice wheat for preparing pasta products. Genetic improvement of durum cultivars continues to be a challenge for wheat breeders and cytogeneticists. Conventional breeding, sometimes combined with hybridization with close relatives, has been instrumental in the improvement of agronomic traits including yield, disease resistance, and grain quality. Tools of classical cytogenetics help manipulate pairing between durum and alien chromosomes and facilitate transfer of alien segments into the durum complement. Sophisticated tools (such as fluorescent GISH) of characterizing alien chromatin integrated into the durum genome effectively aid the chromosome engineering process leading to genomic reconstruction. These techniques of genetic enrichment are nevertheless slow and often tedious. Tools of molecular genetics and biotechnology offer possibilities of direct transfer of value added genes into otherwise superior durum cultivars, thereby increasing the efficiency of breeding. This review presents a summary of conventional breeding, cytogenetic tools of genomic reconstruction, and modern tools of direct gene transfer into commercial durum cultivars. It is concluded that an appropriate combination of these techniques may help speed up the genetic improvement of durum wheat.