Ageratum: A plant genus of the family ASTERACEAE that contains PYRROLIZIDINE ALKALOIDS. Yellow vein disease of Ageratum is caused by a viral DNA complex of a begomovirus (GEMINIVIRIDAE).Commelina: A plant genus of the family COMMELINACEAE of perennial herbs with blue flowers.Geminiviridae: A family of plant viruses where the VIRION possesses an unusual morphology consisting of a pair of isometric particles. Transmission occurs via leafhoppers or whitefly. Some viruses cause economically important diseases in cultivated plants. There are four genera: Mastrevirus, Curtovirus, Topocuvirus, and BEGOMOVIRUS.DNA, Satellite: Highly repetitive DNA sequences found in HETEROCHROMATIN, mainly near centromeres. They are composed of simple sequences (very short) (see MINISATELLITE REPEATS) repeated in tandem many times to form large blocks of sequence. Additionally, following the accumulation of mutations, these blocks of repeats have been repeated in tandem themselves. The degree of repetition is on the order of 1000 to 10 million at each locus. Loci are few, usually one or two per chromosome. They were called satellites since in density gradients, they often sediment as distinct, satellite bands separate from the bulk of genomic DNA owing to a distinct BASE COMPOSITION.Begomovirus: A genus of plant viruses in the family GEMINIVIRIDAE that are transmitted in nature by whitefly Bemisia tabaci.Plant Diseases: Diseases of plants.