Velvet flower (Salpiglossis sinuata, Solanaceae) can be used as an excellent demonstration plant for horticultural crop breeding classes. Salpiglossis produces large trumpetlike flowers exhibiting an assortment of corolla colors and pigmentation patterns. The pistil is large (3 to 4 cm or 1.2 to 1.6 inches long) with a sticky stigmatal tip and flowers can be easily emasculated prior to anthesis. The large pollen grains are shed in tetrads which can be separated and placed on the stigmatal surface. It takes eight to nine weeks from seeding to blooming, with a prolific flowering cycle that comes in flushes. Numerous seeds (about 750 per capsule) are obtained in three weeks after self- or cross-pollination. The influences of three genes that control flower color and pigmentation pattern can be conveniently demonstrated with their dominant and recessive alleles. The R gene controls flower color with red (RR or Rr) being dominant over yellow (rr). The D gene controls the density of pigmentation with solid (DD or Dd) color being dominant over dilute (dd) color. Corolla color striping is controlled by the St gene with striped (stst) being recessive to nonstriped (StSt or Stst) pattern. By using diploid lines of genotypes RRDD (red, solid), RRdd (red, dilute), or rrdd (yellow, dilute) and their crosses, students can easily observe a dominant phenotypic expression in the F1 hybrid and the digenic 9:3:3:1 segregation ratio in the F2 progeny. Another gene (C) that controls flower opening can also be used to show its influence on cleistogamous (closed, selfpollinated, CC or Cc) versus normal chasmogamous (open-pollinated, cc) corolla development. In addition, the induction and use of polyploid (4x) plants in plant breeding can also be demonstrated using this species.
Richard A. Jaynes
Many unusual forms of mountain laurel are under simple genetic control. Myrtifolia (m) and polypetala (p) appear to be controlled by single recessive genes. Two types of banding on the inside of the corolla, fuscata (B) and star-ring (Sr), are apparently controlled by single dominant genes: a recessive lethal trait for albino seedlings occurred among some of the banded crosses. Flower color inheritance is complex. True breeding red-budded or white flowered seedlings have been secured, and true breeding pinks appear possible. Red-bud is recessive to white and wild type.
Rosanna Freyre and Robert J. Griesbach
Plants of Anagallis monelli in their native habitat or in cultivation have either blue or orange flowers. Clonally propagated cultivars, seed obtained from commercial sources and the resulting plants were grown in a greenhouse at the University of New Hampshire. F2 progeny obtained from hybridization between blue- and orange-flowered plants had blue, orange or red flowers. There were no significant differences in petal pH of orange-, blue-, and red-flowered plants that could explain the differences in flower color. Anthocyanidins were characterized by high-performance liquid chromatography. Results indicated that blue color was due to malvidin, orange to pelargonidin, and red to delphinidin. Based on our segregation data, we propose a three-gene model to explain flower color inheritance in this species.
Andrea Quintana, Rosanna Freyre, Thomas M. Davis, and Robert J. Griesbach
(HPLC) confirmed that orange color is attributable primarily to pelargonidin, blue to malvidin, and red to delphinidin. A three-gene genetic model for flower color inheritance with an expected F 2 generation segregation pattern of 52 orange:9 blue:3 red
David M. Czarnecki II and Zhanao Deng
, or red flowers. Our lantana flower color inheritance studies indicated that crosses among yellow, creamy yellow, or white flowers would result in progeny with shades of yellow to white, and crosses between yellow, creamy yellow, or white flowers and