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Crop Sciences

College of Agricultural, Consumer, and Environmental Sciences
University of Illinois at Urbana-Champaign
Randall NelsonRandall Nelson  

Randall L. Nelson

Professor of Plant Genetics; Research Leader and Supervisory Research Geneticist, USDA-ARS;
270 National Soybean Research Center
MC 637
1101 W Peabody Dr
Urbana, IL 61801

Primary Disciplines: Soybean Genetics and Germplasm, NSRL, USDA: Soybean/Maize Germplasm, Pathology and Genetics Research

Ph:   (217) 244-4346
Fax: (217) 333-4639
rlnelson@illinois.edu

Randall L. Nelson

USDA Employee of Plant Genetics; Research Leader and Supervisory Research Geneticist, USDA-ARS;
270 National Soybean Research Center
MC 637
1101 W Peabody Dr
Urbana, IL 61801

Primary Disciplines: Soybean Genetics and Germplasm, NSRL, USDA: Soybean/Maize Germplasm, Pathology and Genetics Research

Ph:   (217) 244-4346
rlnelson@illinois.edu

Research Interests

My research objectives are to acquire, preserve, characterize, evaluate, and utilize the genetic diversity of the genus Glycine. Current project include

  1. evaluating of the level and geographical distribution of genetic diversity in Glycine max and Glycine soja germplasm using DNA markers;
  2. modifying protein and isoflavones in soybean seeds and genetically mapping loci responsible for those changes;
  3. utilizing exotic soybean germplasm to improve the productivity of commercial soybean cultivars;
  4. genetically mapping loci that influence seed yield in soybean;
  5. identifying genetic diversity for quantitatively inherited disease resistance, especially Sclerotinia stem rot caused by Sclerotina sclerotiorum and sudden death syndrome (SDS) caused by Fusarium solani f.sp. glycines;
  6. expanding the USDA Soybean Germplasm Collection to include accessions from those areas of the world poorly represented in the current collection.

Research Accomplishments

Discovered that the duration of seed fill is an important factor in defining yield potential, but the duration and rates of accumulation of N and C during the period determine how much of that potential will be realized. This research was done in cooperation with Dr. Bruce Vasilas, University of Delaware.

Found that high levels of leaf rugosity have a negative impact on apparent photosynthetic rate, are highly associated with high specific leaf weight and may counteract any positive effects of high specific leaf weight. This research was done in cooperation with Dr. Lee Schweitzer, Purdue University.

In cooperation with Dr. Richard Bernard a new allele at the dt1 locus (dt1-t) was discovered. This allele increases the plant height similar to that of the Dt2 Dt2 phenotype (semideterminate) but has most of the morphological characteristics of the dt1 dt1 phenotype (determinate).

Demonstrated for the first time that using exotic germplasm can increase the yield of modern U.S. soybean cultivars. In extensive testing of experimental lines derived from these exotic accessions, identified experimental lines with 50% exotic parentage that were equivalent in yield to the best commercial cultivars included in the test and that significantly exceeded the yield of the adapted parent. Also identified backcross derived lines (containing 75% of the genes of the recurrent, adapted parent) that significantly exceeded the yield of the adapted parent.

Identified a set of 35 RAPD primers that were highly informative in diverse soybean germplasm because of the high number of polymorphic fragments that were consistently reproducible and identified a RAPD marked closely linked to Rsv1 that can be consistently identified in the heterozygous state

Identified exotic germplasm that can be used as parents in yield improvement breeding programs through characterization with DNA markers and comparisons to the genetic base of U.S. commercial cultivars. Approximately 100 exotic accessions have been used to produced high yielding experimental lines with commercial agronomic potential. These exotic accessions and the major ancestral lines of all U.S. cultivars were characterized and compared using RAPD and SSR markers. Cluster analyses were used to group these lines into 11 genetic clusters with 4 outliers. Even though these exotic accessions had been selected as good parents in a yield enhancing breeding program more than half of the accessions were in clusters that did not contain any major U.S. ancestors.

Demonstrated that the genetic base of U.S. soybean breeding is even narrower than had been estimated because of the genetic relatedness among ancestral lines that were previously assumed to be unrelated. One of the 11 genetic clusters identified is the source of 33% of the genes and two other clusters account for more than 22% of the genes in the commercially used U.S. gene pool.

Released 10 high yielding experimental lines that have been widely distributed and incorporated into cultivar development programs at state universities and private companies. The pedigrees of these lines include 18 exotic accessions that represent at least 7 of the 11 genetic groups identified with DNA markers plus two accessions that were classified as outliers. Only 2 accessions used come from genetic groups that contain U.S. ancestral lines that contribute more than 5% to the current U.S. gene pool and 7 accessions come from genetic groups that contain no U.S. ancestral lines.

Demonstrated the much greater genetic diversity within primitive Chinese varieties compared to primitive accessions from either Korea and Japan using DNA markers. This analysis showed the accessions from Korea and Japan are a single gene pool distinct from that of China but much less diverse.

Since 1990, nearly 5,000 annual Glycine have been added to the USDA Soybean Germplasm Collection. Glycine soja lines include 49 from China, 1 from Japan, 38 from S. Korea and 32 from Russia. Glycine max lines include 3,546 from China, 431 from Vietnam, 69 from North Korea, 80 from South Korea, 334 from Indonesia, 51 from Nepal, 146 from Japan, and 76 from Russia. The Collection currently contains 918 perennial Glycine accessions representing 13 species. 329 perennial accessions from 11 species are currently available for distribution. We estimate that within two years seeds from all accessions will be available.

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Links of Interest

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