Author
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Jauhar, Prem |
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Submitted to: National Fusarium Head Blight Forum
Publication Type: Proceedings Publication Acceptance Date: 11/20/2001 Publication Date: 12/6/2001 Citation: Jauhar, P.P. 2001. Problems encountered in tranferring scab resistance from wild relatives into durum wheat. National Fusarium Head Blight Forum Proceedings, p. 188-191. Interpretive Summary: Scab or Fusarium head blight is a devastating disease of bread wheat as well as durum wheat. Most modern wheat cultivars do not have scab resistance. Hybridization with wild relatives offers an excellent option for breeding scab resistance into wheat cultivars. However, several problems are encountered in this approach. The main problem is that when chromatin or chromosome material (that contains the desired genes for scab resistance) from the grass parent is transferred to wheat it may not be stably integrated and hence lost in subsequent generations. Moreover, this chromosome material may bring with it several undesirable traits from the grass parent. It is therefore desirable to make a relatively large number of crosses and screen hybrids with small integrations of the grass chromatin. The smaller the size of the alien chromosome material, the lower the chances of bringing undesirable characters into wheat. Moreover, small integrations are generally more stable. Several problems faced when adopting this approach are described and possible solutions discussed in this article. Technical Abstract: Fusarium head blight (FHB), commonly called scab, is a serious disease of both bread and durum wheats. The fungus infects wheat heads from flowering through grain fill, causing enormous losses to growers in the northern plains area of the United States. The combined direct and secondary economic losses suffered by wheat and barley producers in scab-affected regions of the U.S. during the 1998 to 2000 period were estimated at 2.7 billion dollars. North Dakota and Minnesota account for about 55 percent of the total dollar losses. Most modern wheat cultivars lack resistance to FHB. Durum cultivars, in particular, have no resistance to this devastating disease. However, some of the wild relatives of wheat are rich sources of genes for resistance to diseases including FHB that may be transferred to wheat cultivars by hybridization. In transferring this resistance several problems are encountered. Hybrids can be produced between durum cultivars and wild grasses by embryo culture. However, lack of pairing between wheat chromosomes and grass chromosomes precludes the chances of transferring scab resistance into durum. Even when pairing is induced among the parental chromosomes and alien chromatin is introduced in the wheat genome, the integration may not be stable. Moreover, alien chromatin conferring scab resistance may also bring with it several undesirable traits. This problem could be minimized by reducing the size of integration. This article outlines various problems encountered in transferring scab resistance from wild relatives into durum wheat. It also discusses different approaches to solving these problems. |
