In vitro separation of chimeral pears into their component genotypes
Abu-Qaoud, Hassan Ahmed
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https://hdl.handle.net/2142/23686
Description
Title
In vitro separation of chimeral pears into their component genotypes
Author(s)
Abu-Qaoud, Hassan Ahmed
Issue Date
1989
Doctoral Committee Chair(s)
Skirvin, Robert M.
Department of Study
Agriculture, Plant Culture
Discipline
Agriculture, Plant Culture
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Culture
Language
eng
Abstract
An adventitious shoot regeneration system from leaf explants of several pear cultivars has been developed. Leaves were excised from in vitro grown shoots, transversely cut into halves, and plated onto Petri dishes containing regeneration media. Cultures were kept in the dark for three weeks before adventitious shoots were observed. The effect of different levels of Thiadizuron (TDZ) and Naphthaleneacetic acid (NAA) on shoot regeneration was investigated. Among the different levels of TDZ used, a range of 3 to 7 uM was optimum for most cultivars, while a level of 4.5 to 5 uM NAA gave the best regeneration for the two cultivars, 'Seckel' and 'Louise Bonne Panachee'. The effect of different salts on shoot regeneration was also investigated. Nitsch and Nitsch (1969) salts gave the highest regeneration percentage. It was also found that both nitrogen level and form in the medium played an important role in adventitious shoot formation.
The above regeneration system was used to separate two chimeral pears into their component types. Two cultivars, 'Louise Bonne Panachee' (P1092), a variegated cultivar in which LIII has no chlorophyll and 'Red Hardy', a red mutant in which LII produces anthocyanins were used. Excised leaves of these two cultivars were cultured on a regeneration medium consisting of Nitsch & Nitsch (1969) salts supplemented with 3 uM TDZ and 5.4 uM NAA. After two months, the regenerants were transferred to a Lepoivre's proliferation medium, and later evaluated for their chimeral status. Among 'P1092' regenerants, most were green in color and only a few albino shoots were observed. Among 'Red Hardy' regenerants, both red and green shoots were recovered. The red and green regenerants were assessed for their true-to-type using media supplemented with different levels of sucrose. In addition, total anthocyanins content was also determined. The adventitious regeneration system proved to be useful for chimeral separation when compared to other procedures such as rapid shoot proliferation method.
Shoots of 'Seckel' pear were successfully rooted on Lepoivre media supplemented with 2 to 4 mg/L NAA.
The effect of additional photoperiod on the ex vitro growth of 'Seckel' pear regenerants was studied. Plant growth was significantly improved when plants were grown under a longer photoperiod in the greenhouse.
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