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Crop Science Abstract -

Combining Ability Analysis of In Vitro Callus Formation and Plant Regeneration in Red Clover


This article in CS

  1. Vol. 37 No. 4, p. 1302-1305
    Received: Aug 21, 1996

    * Corresponding author(s): CLOVER@GNV.IFAS.UFL.EDU
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  1. Y. S. Poerba,
  2. K. H. Quesenberry ,
  3. D. S. Wofford and
  4. P. L. Pfahler
  1. Agronomy Dep., Univ. of Florida, Gainesville, FL 32611-0500



Red clover (Trifolium pratense L.) is an important forage species grown in temperate climates around the world. Most genetic transformation methods require regeneration of whole plants from single undifferentiated cells, but one of the major problems encountered in red clover tissue culture is low frequency of plant regeneration. Nine genotypes of red clover, with a range in the level of callus formation and plant regeneration [low (01L, 04L, 30L), intermediate (231, 641, 741), and high (34H, 54H, 71H)] on a B5 basal salts medium protocol, were used in a combining ability study of in vitro callus formation and plant regeneration. Hypocotyl sections from 40 progeny from each of 36 F1 crosses were evaluated on a B5 medium protocol for callus formation at 4 wk of culture and plant regeneration at 12 wk of culture. Analysis of variance showed significant effects of crosses, general combining ability (GCA), and specific combining ability (SCA). Results obtained from diallel analysis (Griffing's Method 4, Model I) showed that crosses with 34H, 54H, or 71H as one parent were among the combinations showing the highest callus diameter and regeneration capacity. Those crosses with OIL, 04L, or 30L as one parent were among the lowest in callus diameter and regeneration response. A highly significant positive relationship (r = 0.91, df = 34) was found to exist between callus diameter and regeneration capacity. Although both general and specific combining ability (SCA) were significant sources of variation for callus diameter and plant regeneration, SCA effects were significant for only a few crosses. The results are in agreement with our previous research showing that red clover regeneration from tissue culture can be improved using recurrent selection methods which exploit additive genetic effects. Initial selection for large callus size should result in improved regeneration capacity.

Journal Series No. R-05338.

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