Molecular characterization of the wheat putative proline-rich protein TaELF7 and its involvement in the negative regulation of Arabidopsis flowering.

Late stages of floret development, such as booting, heading, and anthesis stages, are important steps for determining grain setting and for filling in wheat. Herein, we report the molecular function of Triticum aestivum ELF7 encoding RNA polymerase II-associated factor 1 (PAF1), which may act as a negative regulator in floret development and anthesis stages. Among the six TaELF7-like genes isolated from wheat, TaELF7 like1-A and TaELF7 like2-B showed contrasting expression levels during the late stage of floret development stages, with observation of decreased expression level of TaELF7 like1-A compared to that of TaELF7 like2-B. The full-length TaELF7 like1-A has a 1038-bp open reading frame that contains a proline-rich domain in the N-terminal region and a nuclear localization signal domain in the C-terminal region. TaELF7 like1-A was found to be localized in the nucleus in both tobacco and wheat. Direct interaction of TaELF7 with the RING-type E3 ligase TaHUB2 was confirmed using a yeast two-hybrid system, an in vitro pull-down assay, and a bimolecular fluorescence complementation assay. The flowering time was delayed in TaELF7-overexpressing plants compared to that in the control plants. Expression levels of few floral repressor genes were markedly increased in TaELF7-overexpressing Arabidopsis plants.