CYTOGENETIC MANIPULATION OF DURUM WHEAT BY CLASSICAL AND MOLECULAR TECHNIQUES
Cereal Crops Research
Project Number: 5442-21000-032-00
Start Date: Apr 08, 2008
End Date: Apr 07, 2013
Fusarium head blight (FHB) or scab,caused by the fungus Fusarium graminearum Schwabe, is a serious disease of wheat. The research objective is to develop genetic resistance to FHB in durum, or macaroni, wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes) by exploiting novel sources of resistance in the wild relatives. It has been difficult to identify effective sources of resistance in durum wheat cultivars. However, several wild grasses, including diploid wheatgrasses in the secondary or tertiary gene pool of wheat, are excellent sources of FHB resistance that may be incorporated into durum germplasm. Improved durum germplasm with reliable FHB resistance could then be used to incorporate resistance genes into durum and bread wheat cultivars.
Specific subobjectives of this project are to:
a. Develop alien addition lines involving chromosomes or chromatin, with FHB resistance from diploid wheatgrasses, Lophopyrum elongatum (Host) Á. Löve [= Agropyron elongatum (Host) Beauv.] and Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (= Agropyron bessarabicum Savul. & Rayss).
b. Initiate new crosses with other potential donors such as Thinopyrum junceiforme (Löve & Löve) Löve, 2n = 4x = 28; J1J1J2J2 genomes) and Thinopyrum nodosum [= Lophopyrum nodosum (Nevski) Á. Löve] that may provide new sources of alien chromosomes with FHB resistance.
c. Characterize the added alien chromosome(s) from the wild relatives that confer FHB resistance to durum wheat.
d. Evaluate both FHB resistance and mycotoxin deoxynivalenol (DON) accumulation with the longer-term objective of releasing FHB-resistant germplasm.
e. Assess the genomic relationships between wheat and related species in the intergeneric hybrids.
Alien gene transfer into durum wheat will be carried out by tools of classical and molecular cytogenetics. The cytogenetic techniques will involve sexual hybridization between durum cultivars and wild grasses,coupled with induction of pairing among chromosomes of parental species by manipulation of the pairing-control mechanism(Ph1). This approach will facilitate transfer of alien chromatin into the durum genome, which will then be characterized using fluorescent genomic in situ hybridization (fl-GISH) and chromosome-specific markers. Using this approach, alien addition lines involving diploid wheatgrass (Lophopyrum elongatum and Thinopyrum bessarabicum) chromosomes or chromatin with FHB resistance will be developed. In addition to using these two diploid wheatgrasses as donors of FHB resistance, we will initiate new crosses with other potential donors such as Thinopyrum junceiforme and Thinopyrum nodosum (= Lophopyrum nodosum) that may provide new sources of alien chromosomes with resistance. Fertile hybrid derivatives and stable alien addition lines will be screened for FHB resistance using the techniques we have already standardized.