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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #102305
Title: VESTIGIAL COROLLA IN FLOWERS OF LOTUS CORNICULATUS L.

Author
item Beuselinck, Paul
item MCGRAW, ROBERT - UNIV OF MISSOURI-COLUMBIA

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2000
Publication Date: 7/1/2000
Citation: BEUSELINCK, P.R., MCGRAW, R.L. VESTIGIAL COROLLA IN FLOWERS OF LOTUS CORNICULATUS L.. CROP SCIENCE. 2000. V. 40(4). P. 964-967.

Interpretive Summary: Birdsfoot trefoil (Lotus corniculatus L.) is a plant that is bred for a high-quality feed for livestock. In stands of birdsfoot trefoil we noticed plants with unusual (mutant) flowers. We studied plants with the mutant flowers to determine if they would make intercrossing between birdsfoot trefoil plants easier to conduct. Intercrossing plants is the traditional manner for plant breeders to move traits between plants. The intercrossing requires a well-trained individual with steady hands and good eyesight to move pollen from one small flower to another flower that has had its pollen containing anthers removed. The main objective of this study was to determine if the plants with the mutant flowers were fertile. The plants with the mutant flowers were fertile, but produced few seeds when used a seed plant. Also, the mutant flower trait was unstable since the plants with the mutant flowers started to produce normal flowers. Eventually, the plant that started with all mutant flowers would only produce normal flowers. This research could have had a positive impact for plant breeders by identifying a tool that would make intercrossing between plants easier to conduct. However, the combination of low fertility and the unstable expression of the mutant flower trait is not beneficial to birdsfoot trefoil breeding programs.

Technical Abstract: A naturally occurring floral mutant is infrequently observed in some populations of L. corniculatus. 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 MU-81 used as controls. All vc genotypes produced some pollen which appeared visually to be normal although the quantity of such pollen was variable among the vc genotypes. Pollen germination among the vc genotypes ranged from 0 to about 48%. Only five of 16 vc genotypes produced pods when pollinated by MU-81 and both pod and seed set was less than 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. Reversion of the vc genotypes, from abnormal to normal flower morphology, was common. Reversion was unidirectional. Using the vc mutant to eliminate the need for emasculation in hand-pollination programs depends upon its fertility. The combination of phenotypic instability and reduced fertility make the vc mutant less desirable for use in breeding programs.