'Phyllis Korn' x 'Trude Webster' is a Pentaploid

Two seedlings of Rhododendron 'Phyllis Korn' x 'Trude Webster', which is a Jim Barlup hybrid, have been determined to be a pentaploid 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.

In the case of the pentaploid seedlings of 'Phyllis Korn' (3X) x 'Trude Webster' (4X), a triploid by a tetraploid produced a pentaploid indicating that the triploid seed parent 'Phyllis Korn' was most likely unreduced. In other words, the pentaploid seedlings of 'Phyllis Korn' x 'Trude Webster' having 65 chromosomes most likely received 39 chromosomes from the triploid 'Phyllis Korn' and 26 chromosomes from the tetraploid 'Trude Webster'. Considering the parents are a triploid and a neotetraploid, meiosis may not be normal for either parent.

Summary of Ploidy Levels

Triploid 'Phyllis Korn'
Tetraploid 'Trude Webster',
Pentaploid 2 Seedlings of 'Phyllis Korn' x 'Trude Webster'

Source: Jim Barlap

John and Sally Perkins

'Rwain' X 'L'Engin' is a Tetraploid

Four seedlings of Rhododendron 'Rwain' X 'L'Engin', which were raised by Marc Colombel, have been determined to be a tetraploid 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.

In the case of the tetraploid seedling of 'Rwain' (3X) X 'L'Engin' (4X), a triploid by a tetraploid produced a tetraploid indicating that triploid seed parent 'Rwain' acted as a tetraploid. In other words, the tetraploid seedlings of 'Rwain' X 'L'Engin' having 52 chromosomes most likely received 26 chromosomes from the triploid 'Rwain' and 26 chromosomes from the tetraploid 'L'Engin'.

Summary of Ploidy Levels

Triploid 'Rwain',
Tetraploid 'L'Engin',
Tetraploid 4 Seedlings of 'Rwain' X 'L'Engin'

Source Marc Colombel

John and Sally Perkins