Program overview

My primary research interests are in the physiological and molecular mechanisms of plant interactions with the physical environment. Past research subjects have included air pollutant injury, root cell plasticity in response to nutrient deficiency, plant behavioral movements in response to light and temperature, and plant response to global change (elevated CO2).

Currently my program is focused on the regulation of seasonal dormancy in perennials. One emphasis is the regulation of growth cessation and bud formation in perennials as part of the developmental program that prepares plants to survive potentially damaging winter conditions. Despite being one of the most dramatic landscape and ecosystem events of the annual cycle, very little is known about the physiological and genetic regulation of dormancy in perennial species. Ultimately, a goal is to contribute to assembling a pathway of events from perception of the signal(s) for dormancy induction through to the developmental events associated with bud formation and endodormancy development. A second emphasis is on the molecular and physiological mechanisms of the quantitative chilling requirement for spring bud break. Chilling requirement is a fascinating example of biological 'counting' of the time of cold exposure and is of significant interest to horticulturalists and ecologists alike.

Friday, April 2, 2010

Peach genome sequence released!!!



The peach genome (v1.0) sequence, assembly and annotation was released on Apr. 1 2010.

The above image is a photo of the specific individual tree that was used for the sequence. The tree is a dihaploid of the Lovell rootstock which greatly reduced genetic variation in the sequence and aided smooth assembly of the genome. The genome is about one-half the size (approx. 220Mb on eight chromosomes) of the previously sequenced Populus trichocarpa genome. The sequencing and annotation project has been organized by Dr. Bryon Sosinski (NCSU) and will be updated to include the many high-quality genetic maps that exist within Prunus.

Note that all use of the peach genome sequences in the next several months will be subject to the Fort Lauderdale agreement as described on the GDR website.

See the Clemson press release here: http://www.clemson.edu/media-relations/article.php?article_id=2686

Links to the genome sequence can be found at the Genome Database for Rosaceae (GDR): http://www.rosaceae.org/peach/genome

Tuesday, January 6, 2009

Gene expression in cultivars with contrasting chilling requirements.

The image above contains stems from three different peach cultivars of contrasting chilling requirement. Buds were photographed after two weeks of forcing in a GH following exposure to approximately 600 hours of chilling in the field. The stem on the right is a cultivar rated at 650 CH for bloom and has started bud burst, the middle is 850 CH and the left is 1050 CH. Note the bud swelling of the 850 cultivar relative to the 1050 cultivar. This image also nicely shows the peach 'triple bud' arrangement of two floral buds flanking a single vegetative bud.

Showy/nonshowy flower types from chilling requirement mapping population

Here is a nice shot of the Showy (R) and nonshowy (L) flower phenotype that is segregating in our Contender x Fla92-2C mapping population. The petals are still slightly curled from bud burst. At first glance the nonshowy flowers look as if they have dropped their petals, but often the petals are no larger than the sepals below. Showy flowers are recessive.

Wednesday, August 13, 2008

Presentation at ASPB 2008 in Merida, Mexico


Douglas Bielenberg took a poster to the annual meeting of the American Society of Plant Biologists June 26-July 1, 2008 in Merida, Yucatan, Mexico.

Jimenez S, Li Z, Reighard G, and Bielenberg DG. "Identification of genes associated with bud dormancy entrance using a dormancy-incapable tree mutant" Poster no. P32006 in the Vegetative development session. (http://abstracts.aspb.org/pb2008/public/P32/P32006.html)

Thursday, August 7, 2008

Program overview

Plants are among the most physiologically complex organisms on our planet. This complexity is a consequence of their autotrophic nature and their relative immobility following seed germination. Plants display remarkable physiological plasticity to survive the drastically changing environment throughout a growing season or even within a single day. A perennial organism must be able to tolerate the freezing temperatures of winter, the intense heat and light of summer, drought episodes, air pollution, poor soils, and much more over many years, decades, or even centuries. The many stresses that an organism is exposed to must all be managed to maintain the physiological growth and development that ultimately results in successful reproduction.

My primary research interests are in the physiological and molecular mechanisms of plant interactions with the physical environment. Past research subjects have included air pollutant injury, root cell plasticity in response to nutrient deficiency, plant behavioral movements in response to light and temperature, and plant response to global change (elevated CO2).

Currently my program is focused on the regulation bud formation in perennials as part of the developmental program that prepares plants to survive potentially damaging winter conditions. Despite being one of the most dramatic landscape and ecosystem events of the annual cycle, very little is known about the physiological and genetic regulation of dormancy in perennial species. Ultimately, a goal is to contribute to assembling a pathway of events from perception of the signal(s) for dormancy induction through to the developmental events associated with bud formation and endodormancy development.