Progress 08/01/04 to 07/31/06
Outputs
During the term of this project, we released six soybean lines. SS95-15348 and SS96-14610 were released in 2004, and they are resistant to the soybean cyst nematode. SS95-15348 was released because of its high yield and it offers an alternative to farmers wanting to grow a conventional variety since it is susceptible to Roundup herbicide. It is resistant to race 3 and moderately resistant to race 4 of the soybean cyst nematode. SS96-14610 was released because of its resistance to Roundup herbicide and high yield. It also has resistance to soybean cyst nematode race 3 and moderate resistance to race 14. It is resistant to Phytophthora root rot races 1 and 3. We released in 2006; S02-611RR, S02-3934, SS00-8556, and SS00-8589. S02-611RR and S02-3934RR are Roundup Ready MG V cultivars with broad resistance to races 1, 2, 3, 5, and 14 and resistance to reniform nematode. They are the first Group V Roundup cultivars released with such broad resistance to SCN populations.
SS00-8556 is a MG mid IV, and it has shown resistance to SCN HG type 0 (race 3) based on greenhouse tests at Columbia, MO with a female index of 7, versus 73 for the susceptible check. It is resistant to glyphosate. SS00-8589 is MG early IV, and it also has shown resistance to SCN HG type 0 (race 3) based on greenhouse tests at Columbia, MO with a female index of 9, versus 73 for the susceptible check. It is also resistant to glyphosate. Soybean cyst nematode suppressed US soybean yields 76.2 million bushels during 2005, without data from Iowa, followed by Phytophthora root and stem rot (41.9 million bushels), seedling diseases (32.6 million bushels), and sudden death syndrome (19.8 million bushels). The impact of SCN on soybean production in the USA seems to have declined from 1996 to 2004. We surveyed Missouri for SCN distribution and virulence phenotypes during 2005. The frequency of SCN in Missouri fields was greater in 1998, 63%, than in 2005, 48%. Races 6, 9, and 14 were
detected in some regions of Missouri during 1998 but not during 2005. Most of the SCN populations collected during 2005 were able to parasitize PI 88788, 209332, and 548316, but few were able to parasitize 90763, 89772, and 438389B. None of the populations collected during 2005 developed on 437654.
Impacts
Soybean cyst nematode suppressed US soybean yields more than any other disease during 1996-2005. The impact of SCN on soybean production in the USA seems to have declined from 1996 to 2005. The distribution of SCN races changed in Missouri during 1998-2005, but none of the populations collected during 2005 developed on 437654. This PI will be very useful to breeding programs focused on developing SCN resistant cultivars. Management of SCN can be accomplished with crop rotation, but planting resistant cultivars is a better management tool. We continue to develop and release high-yielding soybean cultivars and lines resistant to SCN.
Publications
- Guo, B., D.A. Sleper, P. Lu, J.G. Shannon, H.T. Nguyen, P.R. Arelli. 2006. QTLs Associated with Resistance to Soybean Cyst Nematode in Soybean: Meta-analysis of QTL locations. Crop Sci. 46:595-602.
- Wrather, J. A., and S. R. Koenning. 2006. Estimates of disease effects on soybean yields in the United States 2003 to 2005. Journal of Nematology 38:173-180.
- Lu, P., J.G. Shannon, D.A. Sleper, H.T. Nguyen, S.R. Cianzio & P.R. Arelli. 2006. Genetics of cyst nematode resistance in soybean PIs 467312 and PI 507354. Euphytica 149:259-265.
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Progress 01/01/05 to 12/31/05
Outputs
Two late maturity group V lines, S01-9391 and S01-9364, with lower linolenic acid content in seed oil and broad resistance to SCN populations have been developed. Both lines average about (4%) linolenic acid which is 50% less than cultivars grown by farmers. They have resistance to populations of SCN HG types 2.5.7-, 1.2-, 0, 2-, and 1.3- (races 1, 2, 3, 5, and 14). At the present time, we have an experimental variety that is ready to release. Its experimental designation is SS-11741 and the goal for developing this selection was to have a high protein line with resistance to SCN. It is resistant to SCN, Phytophthora and glyphosate. It is an early MG IV. It has a protein content of 44.4% and oil content of 21.6% on a dry matter basis. Marker assisted selection (MAS) is an active and important part of the soybean molecular breeding program at the University of Missouri. Identification and genetic mapping of new SCN resistance genes and/or QTLs is in progress with two
mapping populations, Magellan x PI567516C, and Hutcheson x PI458536. as determined in the 2003 and 2004 Regional Quality Traits Tests. More than 20 Heterodera glycines inbred populations differing in virulence characteristics on resistant soybean are being maintained at MU and a collection of frozen nematode stocks for molecular studies has been established. Genomic DNA and RNA have been isolated from each nematode line. We have initiated intraspecific comparative genomic studies to examine the molecular diversity of SCN for polymorphisms in parasitism gene products among H. glycines genotypes that correlate with virulence on resistant soybean. Southern blots suggest that several SCN parasitism genes belong to polymorphic gene families. Furthermore, unique banding patterns for several SCN parasitism genes were identified in a subset of inbred lines that are virulent on SCN resistant germplasm and more detailed characterization of these genes is in progress. To date, we have conducted
large scale sequencing of the H. glycines CLAVATA/ESR gene (HgCle) from 5 different inbred lines, including both genomic DNA and cDNA clones to determine the distribution of HgCle sequences. In total, 28 different HgCle sequences encoding 13 predicted amino acid sequences were identified. Polymorphisms were detected in 52 of the 648 nucleotides most of which were in coding sequences (33/52). Multiple sequence alignments of the nine predicted HgCLE protein sequences revealed a highly variable domain in the HgCLE proteins that appears to be under diversifying selection, and a conserved CLE domain. Interestingly, only two forms of HgCle (A and B) are expressed in parasitic life stages. Restriction fragment length polymorphism (RFLP) analysis on products amplified from cDNA generated from 15 inbred lines showed a correlation of HgCleB with the ability of the nematode to parasitize almost all resistant soybean germplasm. Based on the developmental expression profile of HgCleA and HgCleB,
both genes are induced during parasitism and are not expressed in adult males.
Impacts
The soybean cyst nematode (SCN), Heterodera glycines, has been and remains the most serious pest to soybeans in the United States. The ecological adaptability of this nematode is such that it can apparently thrive and damage soybean wherever the host can be cultivated, a statement that cannot be made for any other soybean pathogen. Presently, about 80% of the domestic farmland planted to soybean is infested with soybean cyst nematode. In 2004, soybean producers nationally lost an estimated $957 million due to this pest alone. Clearly, because losses due to H. glycines are quite large, research and breeding efforts must continue and also take new directions if the economic burden imposed by H. glycines is to be reduced.
Publications
- Shannon, JG, DA Sleper, PR Arelli, JW Burton, RF Wilson and SC Anand. 2005. Registration of S01-9269 germplasm with seed oil low in saturates and resistant to soybean cyst nematode. Crop Sci.45: 1673-1674.
- Eric L. Davis and M.G. Mitchum. 2005. Nematodes: Sophisticated Parasites of Legumes. Plant Physiology 137: 1182-1188.
- Wang, X., M.G. Mitchum, B. Gao, C. Li, H. Diab, T.J. Baum, R. S. Hussey, E.L. Davis. 2005. A parasitism gene from a plant-parasitic nematode with function similar to CLAVATA3/ESR (CLE) of Arabidopsis thaliana. Molecular Plant Pathology 6(2): 187-191.
- Wang, J., A. Replogle, R.S. Hussey, E.L. Davis, T.J. Baum, M.G. Mitchum. 2005. Identification and Functional Analysis of Soybean Cyst Nematode Parasitism Proteins with a Role in Virulence. Phytopathology 95 (6):S108.
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Progress 01/01/04 to 12/31/04
Outputs
Two productive SCN resistant conventional lines (one maturity group IV and one maturity group V) plus four SCN resistant Roundup Ready lines (two maturity group IV and two maturity group V) are being increased for potential release in 2005. We released two lines (SS95-15348 and SS96-14610) that are resistant to the soybean cyst nematode. SS95-15348 was released because of its high yield and it offers an alternative to farmers wanting to grow a conventional variety since it is susceptible to Roundup herbicide. It is resistant to race 3 and moderately resistant to race 4 of the soybean cyst nematode. SS96-14610 was released because of its resistance to Roundup herbicide and high yield. It also has resistance to soybean cyst nematode race 3 and moderate resistance to race 14. It is resistant to Phytophthora root rot races 1 and 3. Marker assisted selection (MAS) is an active and important part of the soybean molecular breeding program at the University of Missouri. In
2004, we have screened approximately 10,000 samples for resistance to soybean cyst nematode (Heterodera glycines Ichinohe) (SCN) race 3 from Prakash Arelli (PA) using ABI 3100 Genetic Analyzer and agarose gel electrophoresis. We have focused on two genes, rhg1 and Rhg4 that have been discovered and mapped. It is important for us to expand our MAS program to include markers for other SCN races. SCN races PA-1, -2, -3, and -5 are most important, but we will continue to work with PA-14 also. In 2005, we anticipate approximately 15,000 samples for MAS. The number of progeny samples to be screened for SCN resistance will be expected to further increase during the 2006 funding period. Our work is in progress to develop a SNP based platform for SCN screening. The genetic mapping of new SCN resistance genes and/or QTLs is in progress with two mapping populations, Magellan x PI567516C, and Hutcheson (G. max) x PI464925B (G. soja). We will soon also have a Hutcheson x PI438503A population to
work with.
Impacts
Soybean cyst nematode reduced soybean production in the United States more than any other pest each year since 1996. The estimated yield suppression due to this nematode declined from 1998 to 2003. This decline is due in great part to farmers increased planting of high yielding SCN resistant soybean varieties. Many of these varieties were developed using SCN resistant parents discovered through research at the University of Missouri.
Publications
- Schmitt, D. P., Wrather, J. A., and Riggs R. D. (eds.) 2004. Biology and Management of Soybean Cyst Nematode, Second Edition. Walsworth Publishing Company, Marceline, MO.
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