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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. |