Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/31/2003
Publication Date: 9/1/2003
Citation: BEUSELINCK, P.R., STEINER, J.J., RIM, Y.W. MORPHOLOGICAL COMPARISON OF PROGENY DERIVED FROM 4X-2X AND 4X-4X HYBRIDIZATIONS OF LOTUS GLABER MILL. AND L. CORNICULATUS L.. CROP SCIENCE. 2003. V. 43(5). P. 1741-1746. Interpretive Summary: Lotus corniculatus L. (broadleafed birdsfoot trefoil) and L. glaber Mill. (narrowleafed trefoil) are forage legumes grown in the United States, Canada, South America and Europe. Our studies have attempted to combine the attributes of both species by intercrossing. Intercrossing is complicated by the different chromosome numbers of each species: L. corniculatus is a tetraploid with 24 chromosomes, and L. glaber is a diploid with 12 chromosomes. One approach is to use the chemical, cholchicine, to double the chromosome number of L. glaber to equal the number of chromosomes of L. corniculatus. Another approach is to identify L. glaber plants that produce abnormal pollen containing twice the normal number of chromosomes in the pollen. The objective of our research was to compare progeny produced from intercrosses between L. corniculatus and L. glaber using the two different approaches and determine if there was an advantage for the progenies developed using one approach over the other. We compared the morphology of the progenies derived from the two different approaches and found that using an L. glaber parent producing abnormal pollen was better than using L. glaber treated with cholchicine. This information is important to plant breeders attempting to intercross different species to improve the performance of birdsfoot trefoil and to other plant scientists that will try to develop more efficient crop plants through interspecies crossing.
Technical Abstract: Unreduced gametes from Lotus glaber Mill. (2n = 2x = 12) may aid intercrossing with L. corniculatus L. (2n = 4x = 24) that results in more desireable progeny than progeny derived from cholcinine-induced tetraploid (4x) L. glaber. The objective of this research was to compare progeny produced from 4x with 2x (4x-2x) and 4x with 4x (4x-4x) crosses and determine if 2n gametes had a heterotic advantage over normal gametes derived from cholcinine-induced tetraploids. Progeny produced from 4x-2x crosses were intermediate to or larger than their parents in their leaf and flower morphology. Progeny from 4x-4x crosses were intermediate to or smaller than their parents in leaf and flower size. Size of leaves and flowers of progeny from 4x-2x crosses were similar to or larger than 4x-4x progeny. Morphological comparisons demonstrated that heterotic expression of progeny from 4x-2x crosses were greater than progeny from 4x-4x crosses. The results indicate that interspecific L. corniculatus x L. glaber hybrids via 2n pollen is effective and advantageous over hybrids produced via cholcicine-induced 4x L. glaber.