Location: Crop Genetics Research2008 Annual Report
1a. Objectives (from AD-416)
Broaden soybean germplasm for genetic resistance to new and emerging nematode populations; identify shifts in genetic profiles and virulence of soybean cyst nematode; and measure effects of cultural practices and diseases on soybean cyst nematode reproduction.
1b. Approach (from AD-416)
Evaluate accessions of Glycine max and Glycine soja for resistance to multiple populations of soybean cyst nematode (SCN), particularly those capable of reproducing on cultivars utilizing PI 88788 as resistance source. Characterize new sources for unique resistance genes and develop molecular markers associated with resistance. Pyramid resistance genes into elite backgrounds of maturity groups III, IV, and V in combination with resistance to predominant fungal pathogens to develop improved germplasm/ cultivars. Characterize SCN field populations to determine effectiveness of current sources of resistance. Predict stability and changes in SCN populations by accelerated selection pressure in greenhouse tests. Determine rhizosphere factors that influence SCN reproduction under different tillage and cropping schemes. Evaluate effects of concomitant infection of charcoal rot and other diseases on SCN reproduction.
3. Progress Report
Populations of unique soybean Plant Introductions with broad-based resistance to soybean cyst nematode (SCN) that were crossed to elite cultivars are being progeny tested. Eleven advanced lines in maturity group V, resistance derived from Fowler, Ananad, and Delsoy 5710 are being yield tested. Eleven advanced lines resistance derived from a new source PI567516C in maturity group V are also being evaluated for agronomic performance. Twenty-four advanced lines in maturity group IVE with resistance derived from PI438489B, PI89772, PI507354, and PI567286 and Fayette are also in yield tests. Thirteen advanced lines with resistance derived from Peking, PI88788 and Hartwig are also in yield tests in both locations at Jackson and Ames Foundation. Sub-line selections are continued in two lines J01-116 and J01-126 for resistance (from Hartwig X PI567516C) to LY1 and Race 2 nematodes. Advanced germplasm line JTN-5203 was entered into USDA Regional tests (Uniform V) and it ranked 9th and yielded nearly 46 bushels/Ac, similar to one of the checks 5601T that was ranked 8th among 29 entries in 13 southern states. SCN resistance is derived from Anand and it is highly resistant to Race 14. The line is resistant to both Stem Canker and Sudden Death Syndrome. This experimental line is being released. Soil Samples were collected from soybean production fields across Tennessee and no HG Type 0 (Race 3) populations were found in field testing and most field populations were able to reproduction on PI88788, the most common source of SCN resistance available commercially. A second year of soybean rhizosphere data has been collected and extreme drought conditions have shown which soil biota is most responsive to environmental conditions. Few of the biological variables selected as influencers of SCN reproduction were as responsive to tillage as soybean cyst nematode. Soybean lines identified as having resistance to Asian soybean rust are being screened in the greenhouse for response to SCN. To date all ASBR resistant lines are susceptible to SCN. NP 303, Component: 3, Problem Statment: b.
1. Impact of management strategies on soybean cyst nematode reproduction. Soybean cyst nematode is consistently the leading limiting plant pathogen affecting soybean yield. Plant resistance has been effective in reducing soybean cyst nematode reproduction but as an almost single source of germplasm is used for plant resistance, soybean cyst nematode population density has risen in production fields and damage is observed. Soil samples were collected from soybean production fields across Tennessee and no HG Type 0 (Race 3) populations were found. Most field populations were able to reproduce on PI88788, the most common source of soybean cyst nematode resistance available commercially. The impact of this research is that producers overestimate the efficacy of the plant resistance they are using to reduce the impact of soybean cyst nematode and yield loss occurs. NP 303, Component 3, Problem Statement: b.
5. Significant Activities that Support Special Target Populations