Journal of Heredity Advance Access published online on May 25, 2008
Journal of Heredity, doi:10.1093/jhered/esn037
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Inheritance of Resistance to Phomopsis Seed Decay in PI 360841 Soybean
From the Cooperative Extension Service, Department of Agriculture, University of Arkansas, Box 357, 2001 Highway 70 E., Lonoke, AR 72086 (Smith); the Department of Crop, Soil, and Environmental Sciences, 115 Plant Science Building, University of Arkansas, Fayetteville, AR 72701 (Chen); and the USDA ARS, Small Grains and Potato Germplasm Unit, 1691 S. 2700 W. Aberdeen, ID 83210 (Jackson)
Address correspondence to P. Chen at the address above, or e-mail: pchen{at}uark.edu.
Phomopsis longicolla Hobbs is the primary cause of Phomopsis seed decay (PSD) in soybean. Infection may result in moldy seed and poor germination. The objective of this study was to conduct inheritance studies to characterize resistance to PSD in plant introduction (PI) 360481. Crosses were made between PI 360841 and 2 PSD-susceptible genotypes, Agripro (AP) 350 and PI 91113, to determine the number of genes for resistance. Additionally, crosses were made between PI 360841 and Phomopsis resistant parents MO/PSD-0259 and PI 80837 to test the allelism of the resistance genes. Seed infection assays were done using seed from parent plants and F2 populations. Chi-square analysis of the resistant x susceptible F2 data fit to a 9R:7S model for 2 complementary dominant genes conferring PSD resistance in PI 360841. Segregation for reaction in the F2 of MO/PSD-0259 x PI 360841 exhibited a good fit to a 57R:7S model for 2 complementary dominant genes from PI 360841 and a different dominant gene from MO/PSD-0259. There was no apparent segregation in the F2 population from PI 360841 x PI 80837 except for one suspicious susceptible plant, suggesting one of the genes in PI 360841 is the same gene in PI 80837 for PSD resistance.
* Deceased author.
Corresponding Editor: Lisa J. Rowland
Received February 8, 2008
Accepted April 14, 2008