Abstract
BACKGROUND: Efficient carbon capture by plants is crucial to meet the increasing demands for food, fiber, feed, and fuel worldwide. One potential strategy to improve the photosynthetic performance of plants is the conversion of C(3)-type crops to C(4)-type crops, enabling them to perform photosynthesis at higher temperatures and with less water. C(4)-type crops, such as corn, possess a distinct Kranz anatomy, where photosynthesis occurs in two distinct cell types. Remarkably, Bienertia sinuspersici is one of the four known land plant species that perform C(4) photosynthesis within a single cell. This unique single-cell C(4) (SCC(4)) anatomy is characterized by dimorphic chloroplasts and corresponding intracellular biochemistry. Because young, emergent Bienertia leaves first exhibit C(3)anatomy and then differentiate into the C(4) anatomy as the leaves mature, Bienertia represents an excellent system to explore the basis for a C(3) to C(4) transition. METHODS: To gain insight into the genes and pathways associated with the C(3) to C(4) transition between emerging young and mature Bienertia sinuspersici leaves, a comparative transcriptome analysis was conducted in which global gene expression and gene ontologies were compared between the two stages. RESULTS: In the emergent leaf, differentially expressed genes and enrichment of ontologies associated with the cell cycle and cytoskeletal dynamics were observed, while the mature leaf displayed enrichment of processes associated with photosynthesis and cellular energetics. Additionally, numerous transcription factors (TFs) associated with metabolic homeostasis, hormone and stress signaling, and developmental regulation were expressed throughout development, with unique TF expression profiles at each stage. These data expand our insights into the molecular basis of Binertia's unique cellular compartmentalization, chloroplast dimorphism, and single-cell C4 biochemistry and provide information that will be useful in the ongoing efforts to transform C(3)-type crops into C(4) type.