Abstract Detail

Ecophysiology

Castro, Mary [1], Borer, Catherine [1], Sapp, Sarah Grace [1], Gamboa Salazar, Keilin [1].

Do plants resorb labile forms of foliar calcium prior to leaf abscission?

During leaf senescence, plants often resorb substantial portions of their labile foliar nutrients, such as nitrogen and phosphorus, and retain these elements for remobilization and use during subsequent growing seasons. In contrast to the more mobile elements, calcium (Ca), is thought to remain in place after it has accumulated in plant foliage. A substantial portion of Ca in the foliage of many plants can be sequestered in a chemically unavailable form, such as calcium oxalate crystals, which is consistent with an inability to resorb and retain Ca. Our recent work, however, demonstrates that flowering dogwood (Cornus florida L.) trees maintain much of their foliar Ca in a labile form, in contrast to many other species. Ca is an essential macronutrient in plants, important for stabilizing cell walls and plasma membranes. It is also a ubiquitous intracellular second messenger, helping plants to sense and physiologically respond to numerous environmental cues. These critical processes depend primarily on labile Ca rather than the chemically sequestered Ca. In this project, we evaluated whether plants may resorb their labile foliar Ca prior to leaf abscission, which we expected to be particularly evident in flowering dogwood because of its unusual Ca physiology and partitioning.
To assess the possibility of Ca resorption during leaf senescence, foliage samples from flowering dogwood and red oak (Quercus rubra L.), were collected two to three times each week during the autumn. Foliage was rinsed, flash-frozen, freeze-dried, ground to a fine powder, and tested for three physiologically relevant pools of foliar Ca, using sequential acidic extractions. Consistent with other recent work, we found greater labile Ca in the foliage of flowering dogwood than in that of red oak. However, our foliar Ca analyses show no evidence of Ca resorption in either species, demonstrating that even the most mobile fractions of foliar Ca are retained by leaves and lost from the trees.

Broader Impacts:

1 - Berry College, Biology, P.O. Box 490430, Mount Berry, GA, 30149, USA

Keywords:
Cornus florida
Calcium
mineral nutrition
phenology
Quercus rubra
Resorption
Senescence.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PEP009
Abstract ID:765
Candidate for Awards:None