One seedling of Rhododendron prunifolium X Rhododendron austrinum, which is a John Thornton hybrid, has been determined to be a triploid using flow cytometry by
Dr. João Loureiro, Dr. Silvia Castro, José Cerca, and Mariana Castro
Plant Ecology and Evolution Group,
Centre for Functional Ecology,
Department of Life Sciences,
Faculty of Science and Technology,
University of Coimbra, Portugal.
Rhododendron prunifolium is a diploid species. Rhododendron austrinum is a tetraploid species.
In this case of this triploid (39 chromosomes), a diploid crossed with a tetraploid produced a triploid indicating normal meiosis occurred where the diploid contributed a 1x gamete (13 chromosomes) and the tetraploid contributed a 2x gamete (26 chromosomes).
Summary of Ploidy Levels
Diploid Rhododendron prunifolium,
Triploid 1 seedling from Rhododendron prunifolium X Rhododendron austrinum,
Tetraploid Rhododendron austrinum
Source: John Thornton
John and Sally Perkins
