Plants from Ethionine-Resistant Alfalfa Tissue Cultures: Variation in Growth and Morphological Characteristics
1981
Reisch, B. | Bingham, E T
Diploid alfalfa, Medicago sativa L. (HG2-2x), was used to select variant cell lines resistant to growth inhibition caused by ethionine. Plants from 23 of 91 mutagenized HG2-2x cell lines grown on 0.02 mM DL-ethionine were morphologically different from the original plant. Plants with multifollolate leaves, elongated petiolules, compact growth habit, jagged leaf margins, and appendage-like leaflets were identified. Several diploid and tetraploid plants outyielded HG2-2x (2n = 16) and HG2-4x (2n = 32), respectively, replicated study of spared plants. Variation also occurred for plant height, length of the longest shoot, and number of primary branches after 7 weeks. Most of the 91 cell lines produced diploid plants (66) whereas the remainder produced tetraploid (20), aneuploid (4), hexaploid (1) plants. Aneuploidy (2n = 33 and 2n 31) was concomitant with morphological abnormalities. Few variants were observed among plants regenerated from mutagenized cultures which were not treated with ethionine. Therefore,. the mutagenic effects of ethionine may be responsible for the appearance of a high frequency of variants. The possibility that useful variation might be obtained from alfalfa tissue cultures is discussed.
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