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Browsing by Author "Sheng, Xiaoyan"

Now showing 1 - 5 of 5
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    Flowering Gene Homologs Regulate Seasonal Growth Changes in Poplar
    Sheng, Xiaoyan (Virginia Tech, 2018-10-19)
    The adaptation of trees to temperate and boreal climates depends on their ability to respond to environmental signals that are markers of seasonal changes in order to survive winter and maximize growth. The genus Populus (poplars) is a model system for identifying the genes and molecular mechanisms that regulate growth and dormancy transitions. Photoperiod and temperature regulate both vegetative and floral phenology. FLOWERING LOCUS T (FT) and FLOWERING LOCUS D (FD) are key regulators of flowering time in Arabidopsis and other plants. The distinct functions of three poplar FD-LIKE (FDL) genes and two FTs were explored through gain-of-function, dominant repression, and CRISPR/CAS9-mediated gene editing. We studied trees in controlled environments, including manipulation of daylength and temperature to mimic an annual seasonal growth and dormancy cycle. Our studies showed that the FDL proteins share less than complete functional equivalency. Among the three paralogs, only FDL2.2 promoted precocious flowering, whereas FDL1 and FDL3 appear to have distinct roles in vegetative growth and phenology. Whereas overexpression of any FDL gene delays short day-induced growth cessation and bud set, only FDL3 coordinately altered leaf development and the transition to secondary growth in a photoperiod-dependent manner. For the first time, we demonstrate distinct functions of the two FT paralogs in vegetative phenology. Study of ft1ft2 double mutants and ft1-specific mutants showed that FT1 promotes dormancy release, whereas FT2 is necessary to sustain growth. Collectively, our results reveal that poplar FTs and FDLs have distinct roles in controlling different aspects of vegetative phenology and woody shoot development.
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    Functional Diversification of Populus FLOWERING LOCUS D-LIKE3 Transcription Factor and Two Paralogs in Shoot Ontogeny, Flowering, and Vegetative Phenology
    Sheng, Xiaoyan; Hsu, Chuan-Yu; Ma, Cathleen; Brunner, Amy M. (Frontiers, 2022-02-03)
    Both the evolution of tree taxa and whole-genome duplication (WGD) have occurred many times during angiosperm evolution. Transcription factors are preferentially retained following WGD suggesting that functional divergence of duplicates could contribute to traits distinctive to the tree growth habit. We used gain- and loss-of-function transgenics, photoperiod treatments, and circannual expression studies in adult trees to study the diversification of three Populus FLOWERING LOCUS D-LIKE (FDL) genes encoding bZIP transcription factors. Expression patterns and transgenic studies indicate that FDL2.2 promotes flowering and that FDL1 and FDL3 function in different vegetative phenophases. Study of dominant repressor FDL versions indicates that the FDL proteins are partially equivalent in their ability to alter shoot growth. Like its paralogs, FDL3 overexpression delays short day-induced growth cessation, but also induces distinct heterochronic shifts in shoot development-more rapid phytomer initiation and coordinated delay in both leaf expansion and the transition to secondary growth in long days, but not in short days. Our results indicate that both regulatory and protein coding sequence variation contributed to diversification of FDL paralogs that has led to a degree of specialization in multiple developmental processes important for trees and their local adaptation.
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    Populus biomass protein-protein interactions and their functions
    Jia, Xiaoyan; Zhao, Mingzhe; Zhao, Chengsong; Sheng, Xiaoyan; Dickerman, Allan; Beers, Eric P.; Brunner, Amy M. (2011-09-13)
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    Regulation of shoot-system development in Populus
    Brunner, Amy M.; Sheng, Xiaoyan; Edwards, Joesph; Fujino, Takeshi; Wang, Chieh-Ting; DiFazio, Stephen P. (2011-09-13)
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    Vernalization and the chilling requirement to exit bud dormancy: shared or separate regulation?
    Brunner, Amy M.; Evans, Luke M.; Hsu, Chuan-Yu; Sheng, Xiaoyan (Frontiers, 2014-12-17)
    Similarities have long been recognized between vernalization, the prolonged exposure to cold temperatures that promotes the floral transition in many plants, and the chilling requirement to release bud dormancy in woody plants of temperate climates. In both cases the extended chilling period occurring during winter is used to coordinate developmental events to the appropriate seasonal time. However, whether or not these processes share common regulatory components and molecular mechanisms remain largely unknown. Both gene function and association genetics studies in Populus are beginning to answer this question. In Populus, studies have revealed that orthologs of the antagonistic flowering time genes FT and CEN/TFL1 might have central roles in both processes. We review Populus seasonal shoot development related to dormancy release and the floral transition and evidence for FT/TFL1-mediated regulation of these processes to consider the question of regulatory overlap. In addition, we discuss the potential for and challenges to integrating functional and population genomics studies to uncover the regulatory mechanisms underpinning these processes in woody plant systems.