*4.1. Cultures*

The *P. duplex* strain used in this study was morphologically identified and its chondriome sequenced and archived in GenBank (MK895949), as described in [58]. It has been maintained in Bold's basal medium [90] in an Erlenmeyer flask on a lab bench with ambient light (adjacent to a window). The *C. vulgaris* strain was collected from a pond on the University of Virginia's College at Wise campus in 2015 and cultured in an aquarium containing mud substrate collected from the same pond. This culture has been maintained in a greenhouse and supplemented with commercial plant fertilizer [59]. Its chondriome has been fully sequenced and is nearly identical to the one archived by Turmel et al. [62] (NC-005255).
