National Jointed Goatgrass Research Program

 

New Proposal-2002

 

TITLE:  Cytoplasmic Background Affects on Gene Flow between Wheat and Jointed Goatgrass

PERSONNEL: R.S. Zemetra               O. Riera-Lizarazu

C. Mallory-Smith          D. Shaner

TIMELINE: July, 2003 to June 2005

HYPOTHESIS:  Differences in the cytoplasmic background of BC1 plants derived from wheat x jointed goatgrass hybrids will affect viability of the BC1 seed reducing or enhancing the potential for gene flow between the two species.

SUMMARY OF PROPOSAL:  We propose to determine if the cytoplasm of the hybrid affects the production and viability of the BC1 generation and whether this difference could result in a difference in the production the BC1 generation in different wheat production regions of the country thus increasing or decreasing the potential for gene flow between wheat and jointed goatgrass.

OBJECTIVES:

1)      Determine the cytoplasmic genome of BC1 plants harvested in 2000 and 2001 in Idaho, Oregon and Washington to determine the maternal parent of the hybrid.

 

2)      Determine the affect of B and D cytoplasms on BC1 production and germination. 

 

3)      Determine if the cytoplasm of field derived hybrids from Colorado, Idaho and Oregon affect BC1 production and germination.

 

JUSTIFICATION: To properly assess the potential for gene flow between wheat and jointed goatgrass and to design effective strategies to minimize this risk, it is necessary to understand all possible parameters that could affect production of both hybrids and backcrosses between wheat and jointed goatgrass.  Recently it has become possible to differentiate between the cytoplasms of wheat and jointed goatgrass (Ishii et al. 2001).  One wheat cultivar from the Pacific Northwest that has a long history of hybridization with jointed goatgrass was found to have a D type cytoplasm more similar to jointed goatgrass than wheat (Edwards et al. 2002).   Since some traits, such as herbicide resistance, rely on an interaction between a nuclear gene product and a cell’s organelles, the agronomic performance of a hybrid or backcross and/or expression of the gene might be reduced or enhanced by the interaction between the nuclear gene products and the cytoplasmic organelles.  Understanding this interaction or lack of interaction would allow for the development of more specific regional management recommendations to minimize the potential for gene migration between these two species. 

METHODS:

Objective 1:  Determine the cytoplasmic genome of BC1 plants harvested in 2000 and 2001 in Idaho, Oregon and Washington to determine the maternal parent of the hybrid.

DNA collected from field derived BC1 plants in 2001 and 2002 will be screened using SSR markers that differentiate between the B cytoplasm of wheat and the D cytoplasm of jointed goatgrass.  Lines with the D cytoplasm will be further screened with SSR markers that differentiate between the D type cytoplasm of Madsen and the D cytoplasm of jointed goatgrass.  This information will be used to determine the direction of the original cross that produced the hybrids found in the field in 2000 and 2001.

Objective 2: Determine the affect of B and D cytoplasms on BC1 production and germination. 

Reciprocal crosses will be made between jointed goatgrass and wheat cultivars from Colorado and the Pacific Northwest to produce hybrids with either the D cytoplasm of jointed goatgrass, the D cytoplasm of ‘Madsen’ wheat or the B cytoplasm of a Midwest or PNW wheat cultivar.  A minimum of twenty hybrids per combination will be produced.  DNA will be extracted from each hybrid to confirm the cytoplasm using SSR markers.  Crosses will then be made to the hybrids using the approach method with jointed goatgrass as the paternal parent.  A minimum of five heads per hybrid will be emasculated and crossed.  Percent seed set on the hybrids will be determined based on number of seed/number of florets emasculated.  Any seed produced will be then be germinated in a growth chamber and percent seed germination will be determined.  Percent seed set and percent seed germination will then be related back to hybrid cytoplasmic genome to determine if  cytoplasmic background influenced production and/or viability of the BC1 generation. 

Objective 3:  Determine if the cytoplasm of field derived hybrids from Colorado, Idaho and Oregon affect BC1 production and germination.

Leaf tissue and mature heads of hybrids will be harvested from wheat fields in Colorado, Idaho and Oregon in 2003 and 2004.  The wheat cultivar being grown where the hybrids were harvested will be documented at time of hybrid harvest.  DNA will be extracted from the leaf tissue of each hybrid to determine the type of cytoplasm in the hybrid using SSR markers.  Hybrid heads with be checked for seed and percent seed set per site/state will be recorded.  BC1 seed will be germinated and percent germination will be recorded.   Seed set and BC1 performance will then be related back to cytoplasm background of the hybrid to determine if there is a difference in BC1 production and germination due to cytoplasm of the hybrid.

LITERATURE CITED:

Edwards, M. L., O. Riera-Lizarazu, C.J. Peterson, C.J.W. Watson, and M.I. Vales. 2002.  Nuclear and cytoplasmic diversity of Pacific Northwest wheat germplasm.  Agronomy Abstracts.

Ishii, T., N. Mori, and Y. Oghihara. 2001.  Evaluation of allelic diversity at microsatellite loci among common wheat and its ancestral species.  Theor. Appl. Genet. 103:896-904.

PLANNED TECHNOLOGY TRANSFER:

Results of this research will be published in refereed journals and presentations will be made local, regional, and national meetings.  Results will also be made available to the jointed goatgrass web page and to other researchers to help determine the potential risk of using herbicide resistant wheat as part of a control strategy for jointed goatgrass.

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