Doctoral Dissertations
Date of Award
12-1984
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Plant, Soil and Environmental Sciences
Major Professor
B.V. Conger
Committee Members
K.W. Hughes, V.H. Reich, J.H. Reynolds
Abstract
The purpose of this study was to demonstrate callus formation and plant regeneration from orchardgrass (Dactylis glomerata L.) leaf tissue cultured in vitro. Vegetative tillers were removed from greenhouse grown plants and the two or three innermost leaves were split longitudinally at the midrib. Beginning at the basal end, six sections 3 mm long were cut from each leaf half and plated on a Schenk and Hildebrandt (SH) medium with 30 μM 3,6-dichloro-o-anisic acid (dicamba).
Initially, leaves from 86 plants were cultured and 14 plants produced a callus which regenerated plants via organogenesis. There was a decline in the frequency of leaf sections that produced callus or regenerated plants with increasing distance, both spatial and temporal, from the shoot apical meristem. Somatic embryos were observed on one callus piece. Plants grown from these embryos demonstrated a dramatic increase in embryogenic potential compared to seed grown plants. Somatic embryos formed on callus and directly on the leaf sections. Direct embryos were shown by histology to arise from mesophyll tissue. Somatic embryos, either singly or attached to the callus mass, germinated and grew into plantlets when placed on auxin-free medium.
Several factors including leaf characteristics, photoperiod and temperature combinations, auxin, and auxin concentrations were tested for their influence on the leaf culture system. Both the abaxial and adaxial leaf surfaces responded similarly in culture. Photoperiod and temperature combinations were significant for the number of sections that callused and callus fresh weight. In a second experiment using embryogenic genotypes, initial culture temperatures were not significant for the number of somatic embryos produced. Dicamba concentrations of 15 and 30 μM were significantly better than other dicamba concentrations ranging from 0 to 240 μM for callus fresh weight and number of shoots counted. The optimum 2,4-dichlorophenoxyacetic acid (2,4-D) concentration was 10 μM for somatic embryo formation. However, it was not significantly better than 30 μM dicamba.
In field observations, there was variation for several agronomic characters within a group of plants regenerated from the same seed grown plant and among groups of plants regenerated from different seed grown plants.
Thirteen additional embryogenic genotypes were identified from 200 plants of the cultivar 'Potomac' and 48 plants from germ plasm accessions grown from seed.
Recommended Citation
Hanning, Gary E., "Callus formation and somatic embryogenesis : from leaf cultures of orchardgrass (Dactylis glomerata L.). " PhD diss., University of Tennessee, 1984.
https://trace.tennessee.edu/utk_graddiss/7815