CHROMOSOME-MEDIATED AND DIRECT GENE TRANSFERS IN WHEAT

Authors: Jauhar, Prem; CHIBBAR, RAVINDRA - NRC PLANT BIOTECHNOLGY

Submitted to: Genome
Publication Type: Book / Chapter
Publication Acceptance Date: 4/8/1999
Publication Date: N/A
Citation: Jauhar, P.P., Chibbar, R.N. 1999. Chromosome-mediated and direct gene transfers in wheat. Genome 42:570-583.

Interpretive Summary: Current wheat cultivars generally lack several desirable traits such as resistance to scab, leaf and stem rusts, and barley yellow dwarf virus. Many of these traits are present in wild grasses. Wide hybridization of wheat with these grasses, coupled with cytogenetic manipulation of the hybrid material, has resulted in the genetic improvement of both bread wheat and durum wheat. Chromosome (rod-like structures that carry genes) engineering techniques have been fruitfully employed to transfer in wheat cultivars, specific disease and pest resistance genes from annual species (e.g., rye) or perennial wheatgrasses. The development of sophisticated techniques such as flourescent in situ hybridization (FISH) has helped in characterizing alien chromosome material in wheat specifying resistance to various pathogens and pests. The recent development of novel gene transfer techniques that allow direct delivery of foreign genes into wheat has opened up new avenues of wheat improvement. Thus, transgenic bread wheat and durum wheat have been produced and methods of direct gene delivery into tnem standardized. These new biotechnological tools are developing rapidly and promise to become an integral part of conventional plant breeding. This article summarizes some of the recent work on conventional and direct gene transfers in reference to genetic improvement of both bread wheat and durum wheat.

Technical Abstract: Wild grasses, including relatives of wheat, have several desirable characters that can be introduced into both bread wheat and durum wheat. The current wheat cultivars lack certain traits, e.g., resistance to Fusarium head blight (scab). Wide hybridization of wheat with grasses, coupled with cytogenetic manipulation of the hybrid material, has been instrumental in the genetic improvement of wheat. Chromosome engineering methodologies, based on the manipulation of pairing control mechanisms and induced translocations, have been employed to transfer into wheat cultivars specific disease and pest resistance genes from annual (e.g., rye) or perennial. The advent of in situ hybridization techniques, e.g., fluorescent GISH combined with Giemsa C-banding, has proved immensely useful in characterizing alien chromatin in wheat specifying resistance to various pathogens and pests. The development in the past decade of novel gene transfer techniques that allow direct delivery of DNA into regenerable embryogenic callus of wheat has opened up new avenues of alien gene transfer into otherwise desirable cultivars of wheat. Thus, transgenic bread wheat and durum wheat have been produced and methods of gene delivery into them standardized. The application of transgenic technology has not only yielded herbicide- resistant wheats, but also helped to improve grain quality by modifying the protein and starch profiles of the grain. These in vitro approaches to gene transfer are developing very rapidly and promise to become an integral part of plant breeding efforts. This article summarizes some of the recent work on chromosome-mediated and direct gene transfers with reference to genetic improvement of both bread wheat and durum wheat.