Title page for ETD etd-11032004-104040
|Type of Document
||Whitley, Kristi Lee
||Factors Influencing Regeneration of Plantlets from Leaf Strips of Strawberry (Fragaria X Ananassa Duch.)
||Master of Science (M.S.)
|Charles E. Johnson
- tissue culture
|Date of Defense
Influence of media age, initial dark period, inoculation with Agrobacterium, and leaf maturity on the regeneration and genetic transformation of two strawberry cultivars was investigated. Four cultivars of blackberry and one raspberry were included to test their response to media age and dark period. Leaf strips of ‘Chandler’ and ‘Cardinal’ strawberry, blackberry, and raspberry were exposed to a four-week dark treatment on modified MS media and subcultured to fresh media. One group of leaf strips was left on the original media for the entire eight weeks. Another group of explants, along with the media treatments was given an additional four-week dark period.
‘Chandler’ strawberry leaf strips exposed to four weeks dark and subcultured onto fresh media produced 19% more plantlets than ‘Chandler’ exposed to eight weeks dark. ‘Chandler’ given a four-week dark period and subcultured onto fresh media produced 58% more plantlets than those left on their original media. ‘Chandler’ produced 97% more plantlets than ‘Cardinal’ strawberry produced with any treatment. ‘Cardinal’ strawberry, blackberry and raspberry responded by producing copious amounts of callus.
When inoculated with Agrobacterium, the highest regeneration rate for ‘Chandler’ or ‘Cardinal’ strawberry leaf strips was less than 0.2 plantlets per leaf strip. This was a 96% reduction in regeneration rate compared to the previous experiment in which Agrobacterium was not introduced.
In an experiment to test the effect of leaf maturity on regeneration rate, 59% more plantlets were produced from unexpanded strawberry leaf strips than leaf strips from newly expanded or mature leaves. Unexpanded ‘Chandler’ strawberry leaf strips, exposed to a four-week dark period followed by subculturing onto fresh media, have a higher regeneration rate than those given an eight-week dark period or left on their original media. ‘Chandler’ strawberry leaf strips from unexpanded leaves have a higher regeneration rate than those from newly expanded or mature leaves.
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