Vestigial Corolla in Flowers of Birdsfoot Trefoil
- P. R. Beuselinck *a and
- R. L. McGrawb
A naturally occurring floral mutant is infrequently observed in some populations of birdsfoot trefoil (Lotus corniculatus L.). The petals of mutant flowers are folded inward and do not extend fully, producing a vestigial corolla (vc), while other floral parts remain normal. The style extrudes through a gap between the rudimentary keel and the folded standard. Consequently, the stigma and style extend beyond the corolla and are exposed. The spatial separation between stigma and anthers could facilitate hand-pollination as it eliminates the need for emasculation. The objective of this study was to determine the fertility of L. corniculatus genotypes expressing vc floral characters. Sixteen genotypes of L. corniculatus expressing the vc phenotype were collected from field grown populations. Pollen from vc genotypes was compared with pollen from genotypes of the germplasm MU-81 used as controls. All vc genotypes produced some pollen that appeared normal, although the quantity of such pollen was variable among the vc genotypes. Mean pollen germination among vc genotypes was 22%, compared with 50% for MU-81. Only five of 16 vc genotypes produced pods when crossed to genotypes of MU-81 and both pod and seed set were less than in control crosses. Normal and abnormal ovules were observed in ovaries of vc genotypes and the reduced fertility may have resulted from smaller, incompletely developed ovules. Unidirectional reversion of the vc genotypes, from abnormal to normal flower morphology, was common. Using the vc mutant to eliminate the need for emasculation in hand-pollination programs depends on its fertility. The combination of phenotypic instability and reduced fertility make the vc mutant less desirable for use in breeding programs.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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