University of Florida

Physiological and structural basis for low survival of in vitro propagated Uniola paniculata genotypes during ex vitro acclimatization.

Uniola paniculata, sea oats, is the primary native dune grass used for beach and dune stabilization and restoration in the southeast United States. Sea oats plants are commonly propagated under nursery conditions from field-collected seed, but concerns regarding the potential introduction of un-adapted ecotypes at revegetation sites have limited the use of seed-derrived material obtained from distant geographic sources. The application of micropropagation technology for sea oats production provides an opportunity to select and rapidly produce ecotypes with ecologically valuable characteristics, particularly from localized sites.

A sea oats micropropagation protocol has been developed. However, significant problems have been encountered when attempting to acclimatize either Stage II microcuttings or rooted Stage III microcuttings to greenhouse conditions (Stage IV). Survival of Stage II microcuttings under greenhouse conditions typically is observed to be very low. Microcuttings, first rooted in vitro (Stage III), exhibit only slightly higher survival ex vitro. When transferred to ex vitro conditions, rooted Stage III plantlets begin to exhibit root and some leaf development but quickly stop growing and then die. This response would occur if the carbohydrate reserves where not sufficient to support growth ex vitro. The severity of this problem appears to be genotype dependant.

The tissue culture environment offers unique control over inputs to the experimental system while some interesting adaptations are also observed. It is likely that the in vitro environment is influencing the low survival observed in sea oats during acclimatization. Modifications of the culture environment are a potential tool for a better understanding of sea oats physiology. This study will determine and compare the anatomical and physiological basis for poor acclimatization of selected sea oats genotypes.

Specific Objectives

  1. Compare and quantify differences in Stage II shoot multiplication, Stage III rooting and leaf development (4 and 8 weeks), and Stage IV acclimatization and growth of two sea oats genotypes exhibiting different capacities fro acclimatization (high to poor).
  2. Compare morphological and anatomical differences between leaves of two genotypes produced in Stage II, Stage III, and Stage IV.
  3. Determine and compare photosynthetic rates of plants of the two genotypes produced in Stage II, Stage III, and Stage IV. Compare enzymatic activity of Rubisco and PEP carboxylase at the same time intervals.

Sea oats in vitro cultures
Sea oats in vitro cultures (left) and Carmen measuring ex vitro photosynthesis (right).

e
Scanning micrograph of sea oats leaf surface (left) and an optical light micrograph of a sea oats leaf cross-section (right).

 

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This project funded by Florida Sea Grant.