Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): 1. Develop breeding/mapping populations and select high-yield resistant breeding lines from the new sources of resistance identified in the first phase of this project. 2. Determine the genetics of resistance of these new sources of resistance and develop molecular markers for these traits. 3. Determine pathogen diversity with emphasis on how this affects the expression of resistance to Phomopisis Seed Decay (PSD) in soybean. Approach (from AD-416): Field screening and laboratory assays will be conducted to determine: 1) The resistance of soybean lines to Phomopisis Seed Decay (PSD); and 2) The genetic and pathogenic diversity of PSD isolates collected and purified from different genotypes of soybean in different geographic origins. During this reporting period, data were analyzed from the 2012 field trails, in which 42 soybean lines (14 from each of three maturity groups MGIII, MGIV, and MGV) tested for resistance to Phomopsis seed decay (PSD) were planted in Kibler, Arkansas, (May 15, 2012) and Stoneville, Mississippi, (April 25, 2012). Based on the seed assay data from 2009 to 2012, 10 soybean Phomopsis seed decay (PSD) - resistant germplasm lines were identified. This year, those 10 resistant lines along with six susceptible lines were planted in Stoneville, Mississippi, on May 30, 2013, and were also planted in Kibler, Arkansas, on June 7. In each location, three field experiments (for maturity groups III, IV and V) were planted with four replications in a split-plot design in which the inoculation treatments (inoculated or non-inoculated) are the main units and soybean lines within each maturity group are the sub-unit. Two harvest times, at the R8 and the R8+2weeks stages (normal vs. delayed), will serve as repeated measures. The inoculated plots will be sprayed with Phomopsis spores at the R5 to R6 growth stage. There are 256 plots planted in each location. Overhead irrigation will be used to increase seed infection. Isolates of Phomopsis (P.) longicolla were collected from seed harvested in past years in different states, and from lower stems of soybean plants grown in two fields in Arkansas and one field in Mississippi. Stem sections were collected from 100 locations in each field using a 20 X 20 m grid. Hundreds of isolates have thus far been collected. Efforts have been made to purify and single-spore those isolates. Selected isolates have been sequenced at internal transcribed spacer (ITS) region to confirm the pathogen identity. Identification of simple sequence repeat (SSR) markers based on the draft genome sequence of a P. longicolla from Mississippi is in progress. For breeding and genetics purposes, the following plant populations are being advanced in Fayetteville, AR, for breeding/mapping purposes: F4 generation: 5002T x PI 417479, 5002T x PI 417050, and R03-984 x PI 417050. F3 generation: R07-R07-10244 x PI 424324B, R04-1268RR x PI 594858A, and R07-10231 x PI 235335. F2 Generation: PI 567635 x R01-976. F1 generation: PI 506647 x R05-3239, PI 567381B x Osage, and PI 567635 x UA 5612. In addition, 41 new lines were selected from sudden death syndrone crosses (12 from 5002T x PI 417050, 12 from 5002T x PI 417479, and 16 from R03-984 x PI 417050). These lines are being evaluated for yield and PSD in Stuttgart, AR. In Illinois, hand pollinations were made in the greenhouse to cross elite Midwestern lines with the PSD-resistant accessions PI 209908, PI 279088, and PI 360841. Although only a low percentage of those were successful, a few pods with putative F1 seeds have been found. Additional crosses will be made in the field in Urbana this summer. PSD-resistant accessions from maturity groups (MGs) II through IV have been planted outdoors, and PIs from higher MGs have been or will soon be planted in the greenhouse for this purpose. Putative F1 seeds that should have PSD resistance will be planted to the extent that this is possible.
Impacts
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Publications
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): 1. Develop breeding/mapping populations and select high-yield resistant breeding lines from the new sources of resistance identified in the first phase of this project. 2. Determine the genetics of resistance of these new sources of resistance and develop molecular markers for these traits. 3. Determine pathogen diversity with emphasis on how this affects the expression of resistance to Phomopisis Seed Decay (PSD) in soybean. Approach (from AD-416): Field screening and laboratory assays will be conducted to determine: 1) The resistance of soybean lines to Phomopisis Seed Decay (PSD); and 2) The genetic and pathogenic diversity of PSD isolates collected and purified from different genotypes of soybean in different geographic origins. During this reporting period, 42 soybean lines (14 from each of three maturity groups MGIII, MGIV, and MGV) that were tested in 2010 and 2011 for resistance to Phomopsis seed decay (PSD) were planted again in Kibler, Arkansas, (May 15, 2012), and Stoneville, Mississippi, (April 25, 2012). Those lines were selected based on the seed assay data on screening 135 lines in 2009, including 36 lines with low levels of PSD at two or more of the test sites and six checks from three maturity groups. Experiments were set up in a split-plot design. The inoculation (using a local Phomopsis isolate in each state at the R5 to R6 growth stage) and non- inoculation treatments are the main plots, maturity groups are the subplots, and lines in each maturity groups are randomized with four replications for each inoculation treatment. Overhead irrigation will be used to increase seed infection. A test comparing 13 foliar applied fungicides was planted on May 15 at the Vegetable Research Station, Kibler, Arkansas. The fungicides will be applied once at the R5 growth stage. Isolates of homopsis longicolla have been collected from seed harvested in Stoneville, MS, in the past years, and from seedlings at the Southeast Research Station, Rohwer, AR. Additional isolates will be collected from northeast Arkansas for inoculation studies. Four isolates from Mississippi have been sequenced at the internal transcribed spacer (ITS) region to confirm the pathogen identity. For breeding and genetics studies, the following plant populations are being advanced in Fayetteville, AR, for breeding/mapping purposes: F3: 5002T x PI 417050, 5002T x PI 417479, R03-984 x PI 417050 F2: R07-10231 x PI 235335, R07-10244 x PI 424324B, R04-1268RR x PI 594858A F1: PI 458130 x R05-3239, PI 506647 x UA 5612, PI 567635 x R01-976 The Phomopsis resistant parents are PI 417050, PI 417479, PI 235335, PI 424324B, PI 594858A, PI 458130, PI 506647, and PI 567635. The following Phomopsis resistant PI�s also were planted in the crossing block for making new crosses this summer in Fayetteville, AR: PI 424324B, PI 458130, PI 506647, PI 567381B, PI 567635, PI 594858A, PI 567102B. In Illinois� location, PI 567381B plants grown in the greenhouse to be crossed with agronomically elite lines adapted to the midwest could not be used due to severe virus infections. Seeds of this accession, carefully chosen for their lack of virus symptoms, have been planted in the greenhouse for crossing this summer to generate agronomically competitive breeding lines with Phomopsis Seed Decay (PSD) resistance derived from PI 567381B.
Impacts
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Publications
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