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Title:Inheritance of Resistance to Soybean Mosaic Virus in Soybeans and Studies on Seed Transmission
Author(s):Bowers, Glenn Russell, Jr.
Department / Program:Plant Pathology
Discipline:Plant Pathology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Plant Pathology
Abstract:Five tropically adapted soybean (Glycine max (L.) Merrill) lines that varied in their reactions to inoculation with seven strains of soybean mosaic virus (SMV) were used in a study to determine the inheritance of resistance to SMV. F(,1), F(,2), and F(,3) populations were inoculated with SMV strains G1, G2, G3, G4, G5, G6, or G7. Resistance to strains G1 to G7, in PI 424131, was shown to be conditioned by an allele at a single locus, R(,1), which exhibited complete dominance under the conditions of this study. Resistance to strains G5, G6, and G7, in HLS, was shown to be conditioned by an allele at a second locus, R(,2), which also was completely dominant. Evidence indicated that the genes for resistance in PI 324068, PI 341242, and PI 424131 are located at the same locus as the previously identified Rsv allele. In certain environments, plants possessing R(,1)- in the presence of r(,2)r(,2) developed necrotic symptoms when inoculated with strain G7, while plants with R(,1)- in the presence of R(,2)- did not develop any symptoms.
Twenty-seven soybean germplasm lines from temperate maturity groups (II and III) were identified as sources of resistance to seed transmission of the 'Illinois severe' isolate of SMV. SMV infection generally delayed the time required for maturity but did not affect the time required for floral initiation. Some soybean lines varied between years in the incidence of mottled seeds produced on SMV-infected plants.
The relationships between the time during the growing season when plants were inoculated with SMV and the delay in maturity, seed weight, number of seeds produced, incidence of mottle seeds, percent seedling emergence, and incidence of SMV transmission through seeds were investigated. A linear relationship (r = -0.93) was found between the time of inoculation and maturity. Seeds produced on plants inoculated after flowering had a lower incidence of mottling and still exhibited some transmission of SMV. Inoculations that took place when plants were young reduced both seed weight and the number of seeds produced per plant. The time of inoculation had no effect on seedling emergence. The strain of SMV with which a plant is infected was found to influence the incidence of seedling emergence, seed coat mottling, and seed transmission. Lines resistant to seed transmission of one SMV strain are not necessarily resistant to other strains. SMV-infected and healthy seeds germinated with equal vigor.
Infectious SMV was detected in the testas, cotyledons, and embryos from immature seeds of both Midwest and Merit soybeans. In mature seeds, infectious virus was detected in embryos of Midwest seeds but not in those of Merit seeds. Seed transmission was only observed in Midwest and not in Merit. Infectious virus was not detected in testas from mature Midwest seeds by a local lesion index, but the same testas contained viral antigen detectable by enzyme-linked immunosorbent assay (ELISA). Viral antigen, detected by ELISA, was associated with anthers from infected soybean plants. Viral antigen was also associated with pollen from soybean lines that transmitted SMV in seeds but not from a line that did not transmit. Inclusion bodies were seen within the nucellus and integuments from ovules of Midwest plants infected with a seed transmissable isolate of SMV. Signs of virus infection were not found within anthers or pollen from infected plants. Virus was donated to the seed by the female parent but was not found in 17 seedlings where only the male parent had been infected.
Issue Date:1980
Description:165 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
Other Identifier(s):(UMI)AAI8108453
Date Available in IDEALS:2014-12-14
Date Deposited:1980

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