Molecular characterization of signaling mechanisms in flowering transition in Arabidopsis and identification of novel flowering QTL in soybean

Sedivy, Eric

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https://hdl.handle.net/2142/45308 Copy

Description

Title

Molecular characterization of signaling mechanisms in flowering transition in Arabidopsis and identification of novel flowering QTL in soybean

Author(s)

Sedivy, Eric

Issue Date

2013-08-22T16:35:40Z

Director of Research (if dissertation) or Advisor (if thesis)

Hanzawa, Yoshie

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Arabidopsis
• Flowering
• TERMINAL FLOWER 1 (TFL1)
• Glycine max
• 5PTASE13
• Glycine soja

Abstract

Flowering response to seasonal photoperiod changes is a critical trait to environmental adaptation and productivity of plants. To better understand flowering two approaches are developed. The first is the molecular characterization of signaling mechanisms in flowering transition in Arabidopsis with the intent to explore basic flowering mechanisms in a model plant species. To this end TERMINAL FLOWER 1 (TFL1), a flowering repressor that controls the activity of the shoot apical meristem (SAM), was selected. Through yeast two-hybrid, we identified nine TFL1 interactors and named them TFL1-IN-LOVE (TIL). Of the nine, TIL3, showed specific binding to TFL1 at a unique TFL1 residue. For this reason TIL3, which encodes an inositol 5-phosphatase (5PTase), was selected for further observation. A functional link between TFL1 and TIL3/5PTase13 was established through root gravitropism experiments, and supported through flowering time experiments where til3-1/5ptase13-1 mutants were shown to reduce the late-flowering effect of TFL1 over-expression. Furthermore, in vivo sub-cellular localization in Nicotiana benthamiana reveals both TFL1 and TIL3/5PTase13 proteins to co-localize in the nucleus and cytoplasm. Finally, Bimolecular Fluorescent Complementation (BiFC) demonstrates in vivo protein-protein interaction between TFL1 and TIL3/5PTase13, supporting our original yeast two-hybrid screen, and reinforcing the hypothesis that TIL3/5PTase13 is important for proper TFL1 function. The second approach devised to understanding flowering is the identification of novel flowering QTLs in Glycine max, the purpose of which is to expand basic knowledge of flowering gained in model species, and apply that knowledge to a cultivate species. In soybean, we conducted QTL mapping using a population of 115 BC2F6 recombinant inbred lines (RILs) that were created from a cross between cultivated soybean, G. max, and its ancestor, G. soja. Agriculturally important traits: flowering time (R1), maturity time (R8), height, yield, lodging, and stem vining were measured for two years in four field locations. QTL mapping analysis identified many previously unidentified QTLs, including 6 independent flowering QTLs with candidate genes, 6 independent maturity QTLs with candidate genes, and 14 QTLs that are observed to affect multiple traits, 3 of which are highly significant.

Graduation Semester

2013-08

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http://hdl.handle.net/2142/45308

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Copyright 2013 Eric Sedivy

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