@PhdThesis{diss_mods_00016936,
  author = 	{Guo, Yuan},
  title = 	{Mutations in FT-, TFL1-, and FRI paralogs of rapeseed (Brassica napus L.) and their effect on flowering time and heterosis},
  year = 	{2015},
  publisher = 	{Christian-Albrechts-Universit{\"a}t zu Kiel},
  address = 	{Kiel},
  keywords = 	{Flowering Locus-T; Terminal Flower-1; Frigida; TILLING; rapeseed; allopolyploid; differential function},
  abstract = 	{The transition from vegetative to reproductive development is a key developmental step in the life cycle of a flowering plant. Floral transition is a complex biological process, which is controlled by multiple flowering genes that respond to environmental cues and endogenous signals. Arabidopsis thaliana is an excellent model system for the Brassicaceae plant family. This study deals with three major flowering time regulators from oilseed rape (Brassica napus), an allopolyploid species which originated from natural hybridization between B. rapa
and B. oleracea.
The aim of this study was to identify and characterize B. napus orthologs of the A. thaliana
flowering time genes FT, TFL1 and FRI. First, I searched the NCBI and Brassica databases to
identify paralogs of FT, TFL1 and FRI in rapeseed. Then, I designed paralog specific primers
to search for mutations in three genes (BnC6FTa/b, BnTFL1-2, BnaA.FRI.a) using a
TILLING mutant population of the European winter type oilseed rape Express 617.
Altogether, 117 mutants were identified. Four non-sense and twenty missense mutant lines
(M3) were further characterized. Homozygous M3 lines were produced by selfing M2 plants.
They were grown in the greenhouse and their flowering time as well as yield components
were analysed.
BnFT paralogs contributed differently to flowering time regulation. Despite the redundancy of
mutations in a single gene, either nonsense or missense mutations in the BnC6FTb gene
resulted in a marked flowering delay, whereas all five BnC6FTa mutant lines started
flowering as the non-mutated parent. Mutations within the BnTFL1-2 paralog had no large
effects on flowering time but on yield components. F1 hybrids between BnTFL1-2 mutants
and non-mutated parents had increased seed numbers per pod and total seeds per plant
suggesting that heterozygous mutations in a TFL1 paralog may impact heterosis in rapeseed.
Mutations within the BnaA.FRI.a paralog showed pleiotropic effects beyond the regulation of
flowering time.
Moreover, the expression of the mutant alleles and their downstream genes were analysed. To
my surprise, a splice site mutation of BnC6FTb, and even a missense mutation of BnaA.FRI.a
had an effect on the transcriptional activities of two downstream flowering time regulators,
BnSOC1 and BnAP1 despite the presence of multiple paralogs. Moreover, the expression of
three BnFLC paralogs was altered due to a missense mutation in a single BnFRI paralog. This
demonstrates multiple interactions between BnFRI and BnFLC paralogs in an allopolyploid
species.},
  url = 	{https://macau.uni-kiel.de/receive/diss_mods_00016936},
  file = 	{:https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/dissertation_derivate_00006085/Thesis-Yuan_Guo-2015-5-5.pdf:PDF},
  language = 	{en}
}