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Title: Toward introducing C4 photosynthesis to C3 oat by use of oat x maize addition lines

Author
item KOWLES, RICHARD - ST. MARY'S UNIV. OF MINN.
item MINNERATH, JEANNE - ST. MARY'S UNIV. OF MINN.
item WALCH, MATTHEW - UNIVERSITY OF MINNESOTA
item BERNACCHI, CARL - CTR. ATMOSPHERIC SCI., IL
item STEC, ADRIAN - UNIVERSITY OF MINNESOTA
item PHILLIPS, RONALD - UNIVERSITY OF MINNESOTA
item Rines, Howard

Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/2007
Publication Date: 3/22/2007
Citation: Kowles, R., Minnerath, J., Walch, M., Bernacchi, C., Stec, A., Phillips, R.L., Rines, H.W. 2007. Toward introducing C4 photosynthesis to C3 oat by use of oat x maize addition lines [abstract]. In: 49th Maize Genetics Conference Abstracts. 49th Annual Maize Genetics Conference, March 22-25, 2007, St. Charles, IL. p. 37.

Interpretive Summary:

Technical Abstract: Stable oat x maize addition (OMA) lines consisting of a single maize (Zea mays L.) chromosome added to the entire oat (Avena sativa L.) genome have been recovered for each of the ten maize chromosomes. The presence of individual maize chromosomes has been associated with several novel phenotypes in the resulting OMA lines, and the effect on photosynthesis of the C3 oat from the addition of a C4 maize chromosome has been investigated. C4-associated phosphoenolpyruvate carboxylase (PEPc) and pyruvate orthophosphate dikinase (PPDK) were previously mapped to maize chromosomes 9 and 6, respectively. Northern blots showed expression of maize C4-specific PEPc in leaf tissue of OMA 9 plants and PPDK in the leaf tissue of OMA 6 plants. Western immunoblotting using anti-PEPc and anti-PPDK polyclonal antibodies on leaf protein extracts showed the presence of PEPc and PPDK enzymes in OMA 6 and 9 lines. Indirect immunocytological tests using monoclonal antibodies on microtomed leaf tissue showed the presence of PEPc and PPDK in the mesophyll cells of OMA 9 and 6 lines. Enzyme assays of leaf protein extracts showed increased activity of PEPc and PPDK with OMA 6 and 9 lines. Because C4 photosynthesis is a pathway mediated by several enzymes, crosses were made between OMA chromosome 9 and OMA chromosome 6 lines to combine PEPc and PPDK in a single oat plant. Northern blots showed expression of both PEPc and PPDK in the F1. CO2 compensation points of OMA 6 and OMA 9 lines were comparable to normal oat, while the CO2 compensation point of the 6 + 9 combination was significantly lower than normal oat, but still more like C3 photosynthesis than C4 photosynthesis.