National Jointed Goatgrass Research Program

 

Progress Report-2002

NOTICE
The following is a progress report containing preliminary data and results that may be modified by future research.
Please contact the listed authors
or Extension Coordinator for additional information.

 

TITLE: Determining Pollen Parent of Backcross Plants from Field Grown Wheat x Jointed Goatgrass Hybrids

PERSONNEL:       Robert Zemetra, University of Idaho

Carol Mallory-Smith, Oregon State University        
Brad Hanson, Ph.D. GRA, University of Idaho
Maqsood Rehman, M.S. GRA, University of Idaho

TIMELINE:  July 1, 2000 to June 30, 2003: Objectives 1 and 2 are on schedule; Objective 3 will be completed 6 months later than originally planned.

ORIGINAL HYPOTHESIS:  Wheat x jointed goatgrass hybrids will produce seed under many different environmental conditions and seed production is not related to specific wheat cultivars.  Molecular techniques can be used to determine whether wheat or jointed goatgrass was the pollen parent.  A herbicide-resistance gene from wheat will move to jointed goatgrass and produce herbicide-resistant hybrids. 

SUMMARY OF PROGRESS: Significant progress has been for made on all three objectives. The BC1 seeds harvested over two years from Idaho, Oregon and Washington have been germinated and total chromosome number and number of C genome chromosomes is being determined.  Germination of the BC1 seed averaged 83% with a mean chromosome number of 42.8 with a range of 33 – 56.  The mean number of C genome chromosomes in the BC1 plants was 5.9 with a range from 4 – 11.  Based on results to date, only 8% of the BC1 plants were produced by a backcross to jointed goatgrass.  Jointed goatgrass from the 2000-2001 pollen flow study was harvested and 5 hybrids were recovered after an initial screening with imazamox.  The 2001-2002 study was harvested and will be screened this winter.  A third field study was planted Fall 2002 to supply additional data.

OBJECTIVES:

1.  Harvest wheat x jointed goatgrass hybrids from fields in Idaho, Oregon, and Washington to determine the frequency of seed set on the hybrid plants.

2.  Use GISH analysis to determine if the pollen parent of the BC1 seed was wheat or jointed goatgrass.

3.  Test pollen flow in field plots of Clearfield wheat for travel distance and pollen viability.

EXPERIMENTAL DESIGN:

Objective 1. Harvest wheat x jointed goatgrass hybrids from fields in Idaho, Oregon, and Washington to determine the frequency of seed set on the hybrid plants.

Collections of wheat x jointed goatgrass hybrids were made in Idaho, Oregon, and Washington.  Up to 25 hybrid plants were collected per site. Each hybrid spike was checked for seed and data were recorded by plant and by site.

Objective 2. Use GISH analysis to determine if the pollen parent of the BC1 plants was wheat or jointed goatgrass.

The harvested BC1 seeds will be tested to determine the pollen parent using GISH.  Roots will be collected and treated according to standard cytological procedures. GISH technique as described by Wang et al. (2000) will be used with Aegilops markgrafii DNA being used as the C genome probe and bread wheat Triticum aestivum being used as the blocking DNA for the A, B and D genomes.  After treatment, the preparations will be observed on a fluorescent microscope to count the number of C chromosomes in each backcross.  Any plant with 7 or less C chromosomes will be considered pollinated by wheat and any backcross with 8 or more C chromosomes will be considered pollinated by jointed goatgrass.  Overall frequency of wheat as a pollen parent compared to jointed goatgrass as a pollen parent will be compared to determine a more realistic estimate of the potential for jointed goatgrass derived backcrosses and subsequent gene movement from wheat to jointed goatgrass to occur in the field.

Objective 3.  Test pollen flow in field plots of Clearfield wheat for travel distance and pollen viability.

A Nelder plot with Clearfield wheat in its center plot as a pollen source and rays of jointed goatgrass radiating outward will be used to determine pollen movement.  Winter barley will be used between the rays of jointed goatgrass. The pollen of wheat, jointed goatgrass, and barley each has a distinctive morphology. The jointed goatgrass will be harvested in designated blocks.  Distance of viable pollen flow and hybridization will be measured.

PROGRESS:

Objective 1. Harvest wheat x jointed goatgrass hybrids from fields in Idaho, Oregon, and Washington to determine the frequency of seed set on the hybrid plants.

Hybrids were collected over two years from sites in Idaho, Oregon, and Washington.  BC1  seed was found on the hybrids collected in all three states.  Amount of seed set varied from 0.3 to 4.9% with some of the variability due to location and the crop in the field.  Overall percent germination of the BC1 seed was 83%.  

Objective 2. Use GISH analysis to determine if the pollen parent of the BC1 plants was wheat or jointed goatgrass. 

Chromosome counts of the BC1 seed harvested over the two years averaged 42.1 chromosomes with a range of 33 to 56.  The 56 chromosome plants indicate that some level of chromosome restitution was occurring in the hybrid plants during meiosis resulting in all 35 chromosomes in the hybrid being passed to the next generation.  GISH analysis is currently being done on these plants to determine the number of C genome chromosomes in the BC1 generation.  To date 65 plants have been counted with an average of 5.9 C genome chromosomes per plant with a range of 4 to 11 C genome chromosomes.  Of these plants, only 5 had more than 7 C genome chromosomes indicating that only 8% of the BC1 plants were produced from a backcross with jointed goatgrass as a recurrent parent.  This indicates that the chance of gene flow via backcrossing is lower than expected based on the level of female fertility observed in the wheat x jointed goatgrass hybrids.

Objective 3.  Test pollen flow in field plots of Clearfield wheat for travel distance and pollen viability.

Seed from the first year field study was harvested and screened with imazamox.  Five hybrid plants survived the initial screening indicating some out-crossing had occurred.  Seed from the second year field study was harvested and will be screened in the winter-spring 2003.  A third year field study was planted near Lewiston, Idaho to supply additional data.

PUBLICATIONS:

Wang, Z., R.S. Zemetra, J. Hansen, A. Hang, C.A. Mallory-Smith, and C. Burton. 2002.  Determination of the paternity of wheat (Triticum aestivum L.) x jointed goatgrass (Aegilops cylindrica Host) BC1 plants using genomic in situ hybridization technique.  Crop Sci. 42: 939-943.

Zemetra, R.S., C.A. Mallory-Smith, J. Hansen, Z. Wang, J. Snyder, A. Hang, L. Kroiss, O. Riera-Lizarazu, I. Vales. 2002.  The evolution of a biological risk program: gene flow between wheat (Triticum aestivum L.) and jointed goatgrass (Aegilops cylindrica Host).  Scientific Methods Workshop: Ecological and Agronomic Consequences of Gene Flow from Transgenic Crops to Wild Relatives.  Ohio State University, Columbus, Ohio. Pgs. 178-187. 

Rehman, M., J. Hansen, R.S. Zemetra, and C. Mallory-Smith. 2002.  Estimating the risk of gene flow between wheat and jointed goatgrass using genomic in situ hybridization (GISH).  Western Society of Crop Science Abstracts pg. (in press)

Zemetra, R.S., C.A. Mallory-Smith, J. Brown, D.C. Thill, O. Riera-Lizarazu, M.I. Vales, J.L. Hansen, Z. Wang, J. Snyder, and S.L. Kunzli. 2002.  Natural gene introgression between plant species: beneficial or detrimental?  Plant and Animal Genome X  Abstracts. Pg. 61.

TECHNOLOGY TRANSFER ACTIVITIES:  The results of this research has been presented at various field days (public and commercial) in Idaho and Oregon,  the Western Society of Weed Science Meeting, Western Society of Crop Science Meeting, and as part of an invited presentations at the Plant, Animal, and Microbe Genome meeting and at the Scientific Methods Workshop: Ecological and Agronomic Consequences of Gene Flow from Transgenic Crops to Wild Relatives.

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