ABSTRACT
PURPOSE: Salvia uliginosa is a desirable ornamental shrub for the landscape with blue flowers and the ability to attract pollinators, but limited variation is commercially available in this species. Mutation breeding is a valuable tool to induce variation in ornamental species. However, many deleterious effects are associated with mutation breeding, including reduced rooting ability of vegetative cuttings. MATERIALS AND METHODS: Cuttings of S. uliginosa were randomly assigned into groups of 10 and exposed to 0, 10, 20, 30, 40, or 50 Gy of gamma rays from a cobalt-60 source to determine an appropriate treatment rate. A follow-up experiment treated 25 S. uliginosa cuttings at 35 Gy to induce favorable mutations. RESULTS AND CONCLUSIONS: Root quality, survival, and plant height were reduced at higher levels of gamma radiation in the M1V1. However, rooting ability was not impacted in M1V2 selections. Additionally, one mutant was isolated from the 35 Gy treatment with variegated leaves for a mutation rate of 4%. Our research determined a treatment rate that induced a dominant mutation in S. uliginosa while minimizing the deleterious influence of gamma radiation.
Subject(s)
Salvia , Plant LeavesABSTRACT
BACKGROUND: Common rosemallow (Hibiscus moscheutos (L.)) is a native wetland perennial taxon that has been widely used as an ornamental landscape plant for several decades. Its showy blooms, attractive form and foliage, and hardiness attracted the attention of plant enthusiasts, leading to extensive hybridization and subsequent selection of superior genotypes. Red foliage color is a desirable trait, therefore we investigated the mode of inheritance of this trait in H. moscheutos subsp. lasiocarpos (Cavanilles) O. J. Blanchard with intraspecific hybrids of H. moscheutos subsp. moscheutos (L.). RESULTS: Two red-foliaged seed parents of Hibiscus moscheutos subsp. moscheutos (L.) were crossed with green-foliaged paternal parent H. moscheutos subsp. lasiocarpos. Two F2 full-sib families (n = 192 and 238) were each found to fit a 3 red: 1 green segregation ratio for foliage color using a Chi square goodness-of-fit analysis. For further evaluation of this segregation pattern, each parent was selfed, as were two red-foliaged F2 plants. The two red-foliaged parents yielded the expected all-red progeny (n = 53 and 178, 1 red: 0 green) and the green-foliaged parent yielded 244 green and 6 red plants, fitting the expected 0 red: 1 green (P = 0.704) ratio. Additionally, progeny from the two red-foliaged F2 plants fit the expected 1 red: 0 green ratio (n = 135 and 120). CONCLUSIONS: Results indicate the appearance of red foliage, in any amount, in the two subspecies utilized and our hybrids of hibiscus to be controlled by a single locus with a dominant allele for red foliage. We propose the gene be called "green foliage" where the dominant allele, G, yields a red foliage phenotype. When the recessive allele, g, is present in the homozygous form, progeny consist of an all-green foliage phenotype for Hibiscus moscheutos (L.). Understanding the mode of inheritance of red-foliage phenotype in hibiscus would prove useful in further ornamental breeding work.
ABSTRACT
Interspecific hybridization in Tecoma Juss. was conducted to develop novel forms for the nursery industry. We report fertile hybrids from the cross T. garrocha Hieron. (pistillate parent) × T. stans (L.) Juss. ex Kunth. Leaf morphology of the F(1) hybrids of T. garrocha × T. stans was intermediate between the parents. GISH also confirmed hybridity. The F(1) hybrids were successfully backcrossed to both parents and self-pollinated to produce BC and F(2) progeny. Tecoma garrocha , T. stans, and T. guarume A. DC. 'Tangelo' were self-fertile. The F(1) hybrids also were crossed with T. capensis (Thunb.) Lindl. and T. guarume 'Tangelo', resulting in three-species hybrids. FISH conducted on F(1) hybrids identified four copies of the 18S internal transcribed spacer region. Further analysis using FISH has the potential to provide information on the evolution of Bignoniaceae and the potential role of polyploidy.
