Browsing by Author "Tsai, Chung-Jui"

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    Plasma membrane phylloquinone biosynthesis in nonphotosynthetic parasitic plants
    Gu, Xi; Chen, Ing-Gin; Harding, Scott A.; Nyamdari, Batbayar; Ortega, Maria A.; Clermont, Kristen; Westwood, James H.; Tsai, Chung-Jui (2021-04)
    Nonphotosynthetic holoparasites exploit flexible targeting of phylloquinone biosynthesis to facilitate plasma membrane redox signaling. Phylloquinone is a lipophilic naphthoquinone found predominantly in chloroplasts and best known for its function in photosystem I electron transport and disulfide bridge formation of photosystem II subunits. Phylloquinone has also been detected in plasma membrane (PM) preparations of heterotrophic tissues with potential transmembrane redox function, but the molecular basis for this noncanonical pathway is unknown. Here, we provide evidence of PM phylloquinone biosynthesis in a nonphotosynthetic holoparasite Phelipanche aegyptiaca. A nonphotosynthetic and nonplastidial role for phylloquinone is supported by transcription of phylloquinone biosynthetic genes during seed germination and haustorium development, by PM-localization of alternative terminal enzymes, and by detection of phylloquinone in germinated seeds. Comparative gene network analysis with photosynthetically competent parasites revealed a bias of P. aegyptiaca phylloquinone genes toward coexpression with oxidoreductases involved in PM electron transport. Genes encoding the PM phylloquinone pathway are also present in several photoautotrophic taxa of Asterids, suggesting an ancient origin of multifunctionality. Our findings suggest that nonphotosynthetic holoparasites exploit alternative targeting of phylloquinone for transmembrane redox signaling associated with parasitism.
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    Synergies and Entanglement in Secondary Cell Wall Development and Abiotic Stress Response in Trees
    Coleman, Heather D.; Brunner, Amy M.; Tsai, Chung-Jui (2021-03-19)
    A major challenge for sustainable food, fuel, and fiber production is simultaneous genetic improvement of yield, biomass quality, and resilience to episodic environmental stress and climate change. For Populus and other forest trees, quality traits involve alterations in the secondary cell wall (SCW) of wood for traditional uses, as well as for a growing diversity of biofuels and bioproducts. Alterations in wood properties that are desirable for specific end uses can have negative effects on growth and stress tolerance. Understanding of the diverse roles of SCW genes is necessary for the genetic improvement of fast-growing, short-rotation trees that face perennial challenges in their growth and development. Here, we review recent progress into the synergies and antagonisms of SCW development and abiotic stress responses, particularly, the roles of transcription factors, SCW biogenesis genes, and paralog evolution.