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|Title:||Maximizing and minimizing pear (Pyrus sp.) chimeral segregation in vitro|
|Author(s):||Al-Wasel, Abdelrahman Saleh Abdelrahman|
|Doctoral Committee Chair(s):||Skirvin, Robert M.|
|Department / Program:||Crop Sciences|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
Agriculture, Plant Culture
|Abstract:||A protocol has been developed for maximizing and minimizing chimeral segregation in vitro of three periclinal pear chimeras ('Louise Bonne Panachee' (p1092) ('LB'); 'Red Hardy' ('RH'); 'Red Comice' ('RC'). Among the factors involved in chimeral stabilization and segregation were growth regulators (TDZ and BA), medium type, and selection at subculture. The pear chimeral cultivars used in this study showed differential responses to some of these factors. 'LB' chimera was a less stable cultivar than 'RC' and 'RH'; red 'RH' was the most stable cultivar.
TDZ strongly destabilized pear chimeral cultivars, especially 'LB'.
The 'LB' chimera was most stable on single phase MMS. However, single and double phase MMS produced shoots with very clear chimeral patterns. 'RC' was more stable on single and double phase MMS than on SMS which resulted in more offtypes (green); red 'RH' was quite stable on all MMS and SMS media.
Selection at subculture increased the stability and clarity of 'LB' chimera, when it was grown on a medium proper for its maintenance. The stability and instability of pear chimeras was found to be associated with the rate of proliferation and callus formation.
The clarity of the 'LB' chimera was highest at low levels of BA (2 to 16 $\mu$M); 18 and 20 $\mu$M BA gave least clear chimera. TDZ strongly reduced the chimera clarity of 'LB' at all levels. Leaf and stem anthocyanin of red sports responded differently to the growth regulators and medium types. Stem anthocyanin was more stable than leaf anthocyanin.
In general, pear cultivars proliferated better on MLP, than SMS. The chimeral patterns of 'LB' were very clear on SMS, making it easy to screen them for their chimeral status. MLP, with levels of BA greater than 2 $\mu$M, gave high proliferation rates for both 'LB' chimera and selected green 'RH'; levels of BA greater than 4 $\mu$M resulted in high proliferation rates for 'RC'. Red 'RH' gave significantly more shoots at BA levels greater than 8 $\mu$M. In terms of TDZ, the highest proliferation rates were found at the lowest levels of TDZ (1 to 6 $\mu$M). Callus formation was stimulated at high levels of TDZ, BA, or NAA.
Overall, the most adventitious shoots from leaf explants of all cultivars were obtained at 4.5 $\mu$M TDZ. High levels of TDZ yielded more shoots from stem explants than low levels. NAA at 5 and 4.5 $\mu$M were good for leaf and stem regeneration of red 'RH', respectively.
The above regeneration systems were used to separate variegated 'LB' (in which the LIII has no ability to synthesize chlorophyll) and red 'RH' (a red mutant in which the LII is capable of producing anthocyanin), chimeral pears into their constituent genotypes and to confirm the purity of their selected types.
The pear cultivars showed differential responses to rooting media. 'RC' rooted better over a wide range of IBA and NAA than other cultivars. (Abstract shortened by UMI.)
|Rights Information:||Copyright 1994 Al-Wasel, Abdelrahman Saleh Abdelrahman|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9512281|