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Abstract Detail

Functional Genetics/Genomics

Liu, Xiang [1], Xiang, Jenny [1], Franks, Robert [1], Xie, Deyu [2].

Functional Characterization of Terminal Flower1 Homolog in Cornus canadensis – Deciphering its role in evolution of inflorescences in Cornus.

TERMINAL FLOWER1 (TFL1) is known to play an important role in regulating the transition from vegetative to reproductive growth in Arabidopsis thaliana via interactions with LEAFY (LFY) and APETALA1 (AP1). Different roles of TFL1 homologues from other species in the process of inflorescence development have been reported. Our recent comparative analysis of CorTFL1 gene expression among Cornus species suggested CorTFL1 may be a key player in variation of inflorescence types within Cornus through interaction with CorAP1. Our previous study of overexpressing TFL1 homologs from C. florida and C. canadensis in Arabidopsis revealed a delay in the onset of flowering in wild type Arabidopsis and a rescue of the phenotypic defect of mutant tfl1-18. However, the role of CorcanTFL1 in the endogenous system of Cornus was unknown. Here we report results from functional analysis of the gene in C. canadensis. In this study, we introduced different constructs of CorcanTFL1 into wild type C. canadensis via an Agrobacterium-mediated stable transformation system. The study generated more than 30 individual transgenic plants. Analysis using qRT-PCR indicated that CorcanTFL1 expression was downregulated in antisense and hairpin transgenic plants, while the expression was upregulated in all overexpression transgenic plants. Compared to wild type plants, the inflorescence buds of CorcanTFL1-downregulated plants emerged on apex of the stem as early as in 8 months (17 months on an average after planting, an average of approximately 4 months earlier than the wild type). Meanwhile CorcanTFL1 overexpressing plants failed to transition to flowering during the first three years after planting. In addition to alteration of flowering time, dramatic morphological changes were also observed in some downregulated transgenic plants. The changes included conversion of leaves at upper most node into white, petalloid bract-like structure, conversion of axillary bud at upper most node into small secondary inflorescence, and phyllotaxy of inflorescence-bearing stem from opposite to alternate. Despite the fact that the inflorescence architectures were the same in these downregulated plants, the inflorescence size (number of flowers per inflorescence) appeared to have been reduced. However, in most downregulated plants, no apparent change in flower number in each inflorescence compared to the wild type was observed. These observations suggest that CorcanTFL1 plays a critical role in floral initiation and early inflorescence development in Cornus, congruent with the finding from previous comparative gene expression analysis. This is the first report of gene functional characterization of a floral/inflorescence regulator in Cornus.

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1 - North Carolina State University, Plant and Microbial Biology, Raleigh, NC, 27695, USA
2 - North Carolina State University, Raleigh, NC, 27695, USA

Inflorescence development
Terminal Flower1
Gene function characterization.

Presentation Type: Oral Paper
Session: 8, Functional Genetics and Genomics
Location: 109/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 10:45 AM
Number: 8009
Abstract ID:490
Candidate for Awards:Margaret Menzel Award

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