Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2005
Publication Date: 3/1/2006
Citation: Bent, A.F., Hoffman, T.K., Schmidt, J.S., Hartman, G.L., Hoffman, D.D., Xue, P., Tucker, M.L. 2006. Disease- and performance-related traits of ethylene-insensitive soybean. Crop Science. 46(2):893-901. Interpretive Summary: Ethylene controls multiple plant processes that impact agronomic traits. In multiple plant species, lines have been developed that exhibit reduced ethylene responsiveness. Published studies of such lines have primarily been laboratory rather than field-based. We performed laboratory and field studies to assess ethylene-insensitive soybeans. We observed elevated susceptibility to white mold, reduced cyst formation by soybean cyst nematode, alterations in plant architecture, earlier maturity date, and poor stand establishment and/or poor yield in some but not all environments. No changes were observed in seed total protein/oil content, flowering date, plant height, leaf chlorophyll or late-season leaf senescence. This information is important to plant biologists, physiologists and pathologists.
Technical Abstract: The plant hormone ethylene controls many beneficial plant responses, but because ethylene can promote chlorosis, senescence, disease severity and fruit over-ripening, plant lines that exhibit reduced ethylene responses have been developed for a number of species. Published studies of these lines have often used plants grown in a growth chamber or glasshouse. We previously isolated and characterized ethylene-insensitive soybean lines. The present study combined laboratory-based experiments with field performance trials. Lab tests revealed that ethylene insensitivity reduced root colonization by soybean cyst nematode. Previous lab experiments had indicated a slight increase in susceptibility to Septoria glycines in ethylene-insensitive soybean, but this was not detected in field plots. Susceptibility to white mold (Sclerotinia sclerotiorum) was greatly increased in field tests of the ethylene-insensitive lines. Subtle alterations in plant architecture were evident. Ethylene-insensitivity also reduced ethylene-activated leaf chlorosis and abscission in lab tests of healthy young plants. However, in the field, leaf chlorophyll content was similar and late-season leaf senescence occurred at similar rates in ethylene-insensitive plants and their isogenic ethylene-sensitive parents, suggesting that ethylene-mediated processes are not a main determinant of late-season senescence of soybean leaves. The overall protein and oil content of seeds was similar between field-grown ethylene-sensitive and insensitive lines. Seed yield from the ethylene-insensitive lines was notably undependable, being similar to the parental line in some field locations but severely reduced in other environments.