H: Monday, June 13, 2011

'Margaret Abbott' is a Tetraploid

'Margaret Abbott' (Frank Abbott) [4x]
Rhododendron prinophyllum [2x] X Rhododendron calendulaceum [4x]
Spring 2009 Saxtons River, VT
S and J Perkins

Rhododendron 'Margaret Abbott', which is a Frank Abbott hybrid documented as Rhododendron prinophyllum X Rhododendron calendulaceum, has been determined to be a tetraploid using flow cytometry by

Dr. João Loureiro, Dr. Silvia Castro, José Cerca Oliveira, 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 'Margaret Abbott' was named by Frank to honor his wife. Frank was amazed he crossed a pink with a yellow to produce this lone fragrant ruffled white flower with a yellow flare. See A Love Affair With A Flower by Marge Runnion. See Frank Abbott's Village of Azaleas by John and Sally Perkins.

Notice in the image above on the flower facing forward, 'Margaret Abbott' has, at the end of the stamens, tagged anthers, such anthers rarely appear on a deciduous azalea. 'Margaret Abbott' is known to be partially seed fertile but does not appear to have viable pollen.

Notice, also, for 'Margaret Abbott' that the diploid is the seed parent and the tetraploid is the pollen parent. For deciduous azaleas, diploids usually accept pollen from tetraploids but tetraploids usually reject pollen from diploids. See Rules of Engagement by John and Sally Perkins.

In the case of the tetraploid 'Margaret Abbott', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid seed parent. In other words, 'Margaret Abbott' having 52 chromosomes received something on the order of 26 chromosomes from the diploid Rhododendron prinophyllum and 26 chromosomes from the tetraploid Rhododendron calendulaceum. See Unreduced Meiosis. See Ploidy of Deciduous Azaleas Species.

In every other case we have tested where a diploid deciduous azalea is crossed with a tetraploid deciduous azalea, the resulting offspring have been triploids having 39 chromosomes receiving 13 chromosomes from the diploid seed parent and 26 chromosomes from the tetraploid pollen parent. See 2X4 for Deciduous Azaleas. See Normal Meiosis.

Natural interactions of diploid deciduous azalea species and tetraploid diploid deciduous azalea species do occur in places such as Audra State Park. Plants that appear to be interploidy hybrids have tested as triploid and tetraploid. The ploidy results for 'Margaret Abbott' indicated that unreduced gametes of the diploid seed parent may be one of the mechanism causing tetraploids to be produced by diploid X tetraploid interaction. See Audra State Park: Ploidy Haven. See Rhododendron prinophyllum by Elizabeth Carlhian. See Rhododendron arborescens by Susan Clark. See Rhododendron calendulaceum by Joe Bruso.

The hybridizers of the Ghents, including some done by Ed Mezitt, the Rusticas, and the Northen Lights series crossed diploid and tetraploid deciduous azaleas. See Ghent. See Rustica. See Mezitt.

For large leaf elepidote hybrid Rhododendrons we have discovered several instances where a diploid X tetraploid results in tetraploids as well as triploids and diploids. For instance, Rhododendron 'Horizon Monarch', which is a Ned Brockenbrough hybrid documented as 'Nancy Evans' x 'Point Defiance', has been determined to be a tetraploid. 'Nancy Evans' has been determined to be a diploid and 'Point Defiance' has been determined to be a tetraploid. See 2X4 for Large Leaf Elepidotes. See 4X2 for Large Leaf Elepidotes.

For large leaf elepidote hybrid Rhododendrons we have discovered fertile triploids and the offspring of these triploids can be tetraploids. For instance, Rhododendron 'Countess of Derby', which is a 1913 Henry White hybrid documented as 'Pink Pearl' x 'Cynthia', has been determined to be a tetraploid. Both 'Pink Pearl' and 'Cynthia' have been determined to be triploids. See It is 1913 So What Do You Do? by John and Sally Perkins. See Fertile Triploids. See Pink Pearl.

For large leaf elepidote hybrid Rhododendrons we have discovered tetraploids can produce diploid offspring in the first generation. See Super Reduced Meiosis.

Although there are no known polyploid elepidote species, many elepidote hybridizers, including Barlup, Bones, Brack, Briggs, Brockenbrough, Broughton, Bruns, Colombel, Croux and Fils, de la Sablière, Endtz, Evans, Felix and Dijkhuis, Fujioka, Greer, Gehnrich, Hachmann, Hartman, Heinje, Henny and Wennekamp, Hobbie, Kavka, Kehr, Korn, Koster, Lem, Loder, Lofthouse, Mangles, Markeeta, McCullough, Mossman, Murcott, Naylor, Patterson, Pearce, Rabideau, Sanders, Schannen, Seabrook, Standish and Noble, Stead, Stockman, Thornton, vanNes, VanVeen, von Martin, Walton, Waterer, White, Whitney, Wilson, and Woodward have worked with or produced ployploid elepidotes hybrids and in some cases are best known for these polyploid hybrids.

Clarence Towe aided us in confirming that the plant pictured above is 'Margaret Abbott'.

To see a poster on the ploidy results (Click on the poster image to enlarge):

Ploidy Research Poster by José Cerca Oliveira.

To see the research team:

Research Team of Dr. João Loureiro, Dr. Silvia Castro, José Cerca Oliveira, and Mariana Castro.

To see other images of Frank Abbott's azaleas visit the following:

Abbott Azaleas by S & J Perkins.

The "In The Collections" web page of the Arnold Arboretum includes a reference to our ploidy research.

Summary of Ploidy Levels

Diploid Rhododendron molle,
Diploid Rhododendron prinophyllum,
Diploid 'Frank Abbott',
Diploid "Jane Abbott" (grex),
Diploid 'Nancy Evans',
Triploid 'Cynthia',
Triploid 'Pink Pearl',
Tetraploid Rhododendron calendulaceum,
Tetraploid 'Countess of Derby',
Tetraploid 'Horizon Monarch',
Tetraploid 'Margaret Abbott',
Tetraploid 'Point Defiance'

Source: John Abbott

Ploidy Results by Groups

Rhododendron Species,
Diploid Deciduous Azaleas,
Triploid Deciduous Azaleas,
Tetraploid Deciduous Azaleas,
Diploid Large Leaf Elepidotes,
Triploid Large Leaf Elepidotes,
Tetraploid Large Leaf Elepidotes,
Diploid Lepidotes,
Triploid Lepidotes,
Tetraploid Lepidotes,
Diploid Everegreen Azaleas,
Triploid Evergreen Azaleas,
Fertile Triploids,
Northern Lights, and

The following people and organizations donored samples for this reasearch:

John Abbott,
Vivian Abney of East Fork Nursery,
Arnold Arboretum,
Audra State Park,
Bartlett Arboretum,
Jim Barlup,
Bruce Clyburn,
Jane Brooks,
Joe Bruso,
Werner Brack,
Ned Brockenbrough,
Canobie Lake, NH,
Dick Cavender,
Connecticut College Arboretum,
Marc Colombel,
Mike Creel,
Al Fitzburg,
Robert Fox,
Harold Greer of Greer Gardens,
George Hibben,
Highstead Arboretum,
Don Hyatt,
Lindy Johnson of Appalachian Native Plants,
Richard Jaynes of Broken Arrow Nursery,
Doug Jolley,
Fred Knippel,
Longwood Gardens,
Ron Miller,
Dick Murcott,
Planview Nursery,
John and Sally Perkins,
Ron Rabideau of RareFind Nursery,
Ellie Sather of Whitney Gardens,
Stoddard Blog, NH,
John Thornton,
Hendrik Van Oostand of Azaleatuin,
Kathy Van Veen of Van Veen Nursery

John and Sally Perkins
Copyrighted material of Rosebay Blog