Effects of Foliar Redox Status on Leaf Vascular Organization Suggest Avenues for Cooptimization of Photosynthesis and Heat Tolerance

• Main Authors: Jared J. Stewart, Christopher R. Baker, Carlie S. Sharpes, Shannon Toy Wong-Michalak, Stephanie K. Polutchko, William W. Adams, Barbara Demmig-Adams
• Format: Article
• Language: English
• Published: MDPI AG 2018-08-01
• Series: International Journal of Molecular Sciences
• Subjects: Arabidopsis; antioxidant; C-repeat binding factor; phloem; photoprotection; photosynthesis; PsbS; tocopherol; xylem; zeaxanthin
• Online Access: http://www.mdpi.com/1422-0067/19/9/2507

The interaction of heat stress with internal signaling networks was investigated through Arabidopsis thaliana mutants that were deficient in either tocopherols (vte1 mutant) or non-photochemical fluorescence quenching (NPQ; npq1, npq4, and npq1 npq4 mutants). Leaves of both vte1 and npq1 npq4 mutants that developed at a high temperature exhibited a significantly different leaf vascular organization compared to wild-type Col-0. Both mutants had significantly smaller water conduits (tracheary elements) of the xylem, but the total apparent foliar water-transport capacity and intrinsic photosynthetic capacity were similarly high in mutants and wild-type Col-0. This was accomplished through a combination of more numerous (albeit narrower) water conduits per vein, and a significantly greater vein density in both mutants relative to wild-type Col-0. The similarity of the phenotypes of tocopherol-deficient and NPQ-deficient mutants suggests that leaf vasculature organization is modulated by the foliar redox state. These results are evaluated in the context of interactions between redox-signaling pathways and other key regulators of plant acclimation to growth temperature, such as the C-repeat binding factor (CBF) transcription factors, several of which were upregulated in the antioxidant-deficient mutants. Possibilities for the future manipulation of the interaction between CBF and redox-signaling networks for the purpose of cooptimizing plant productivity and plant tolerance to extreme temperatures are discussed.