Source: NORTH CAROLINA STATE UNIV submitted to
GENETIC BASIS OF FLORAL AND LEAF CHARACTERISTICS OF THE GERBERA DAISY
 
PROJECT DIRECTOR: KLOOS, W. E.
 
PERFORMING ORGANIZATION
GENETICS
NORTH CAROLINA STATE UNIV
RALEIGH,NC 27695
 
NON TECHNICAL SUMMARY: The Gerbera daisy has a wide variety of floral and leaf traits which can provide the basis for new variety development once their inheritance is understood. This project examines the genetic basis of floral and leaf characteristics of the Gerbera daisy.
 
OBJECTIVES: The main objectives include determining the genetic basis of flower colors, flower color patterns, giant flower size, flower fragrance, leaf variegation, and leaf shape of the Gerbera daisy. Understanding the inheritance of these floral characteristics is important for the development of new and attractive varieties for the florist and nursery market. In parallel with genetic investigations, we will be determining the flavonoid and carotenoid composition of flower petals of different colors to establish chemical markers and will determine the chemical basis of rare fragrance. The trichomeless (glossy leaf) gene (Trl) will be introduced into homozygous scalloped-leaf cultivars to produce an attract shiny scalloped-leaf gerbera line. We will continue to introduce the powdery mildew-resistance and frost tolerance gene (Pmr) into our various color, color pattern, flower morphotype, and leaf types of gerberas for the development of robust perennial lines for the nursery market.
 
APPROACH: The determination of allelic status and possible linkage relationships among separate genes controlling the basic flower colors and color patterns will require the completion of F1 progeny self and full-sib crosses to provide sufficient F2 progeny for analysis. F1 progeny and backcross(testcross) progeny have been characterized. The petal vacuole flavonoid and plastid carotenoid pigments will be analyzed microspectrophotometrically and by high-pressure liquid chromatography, following extraction. Vacuole pH will be determined microspectrophotometrically. Giant-flowered cultivars will be crossed among themseves and to homozygous wild-type and miniature-flowered varieties in an initial attempt to determine dominance relationships and assess the possibility of simple mendelian inheritance. Furthermore, F1, backcross, and F2 progeny will also be produced and frequency of flower size classes determined. The rare fragrant cultivars will be crossed among themselves and to non-fragrant cultivars to gain insight on dominance relationships and a possible genetic basis. The volatile substances producing the fragrance will by analyzed by GC mass spectroscopy, following extraction from charcoal-tenax columns. It is anticipated that by continued selection of the most fragrant cultivars for breeding we may increase the intensity of fragrance. The inheritance of leaf variegation and leaf shape (arrow-head, elliptical, and scalloped) will be investigated by making crosses to produce F1, backcross, and F2 generations for analysis.
 
CRIS NUMBER: 0186765 SUBFILE: CRIS
PROJECT NUMBER: NC06594 SPONSOR AGENCY: CSREES
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Oct 1, 2000 TERMINATION DATE: Sep 30, 2005

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
201212010802.220%
201212310802.220%
202212010802.210%
202212310802.210%
204212010802.220%
204212310802.220%

CLASSIFICATION HEADINGS
KA202 - Plant Genetic Resources
KA201 - Plant Genome, Genetics, and Genetic Mechanisms
KA204 - Plant Product Quality and Utility (Preharvest)
S2120 - Herbaceous perennials and decorative greens
S2123 - Bedding/garden plants
F1080 - Genetics
G2.2 - Increase Efficiency of Production and Marketing Systems


RESEARCH EFFORT CATEGORIES
BASIC 40%
APPLIED 60%
DEVELOPMENTAL (N/A)%

KEYWORDS: gerbera; flowers; flower color; plant size; odor; leaf shape; plant genetics; ornamental plants; phytochemistry; traits; inheritance; new varieties; plant improvement; flavonoids; carotenoids; cultivars; gene transfer; plant disease resistance; powdery mildew; frost resistance; breeding lines; hplc (chromatography)

PROGRESS: Oct 1, 2000 TO Sep 30, 2005
One of the objectives of this study was to determine the mode of inheritance of the major flower types of Gerbera hybrida. Genotypes of parents used in crosses were determined by testcrosses to single-flowered, ligulate floret cultivars similar in phenotype to the wild, parental gerbera species. They indicated that the single(wild-type) flower type was recessive to the crested and spider flower types and was given the genotype crcrspsp. For each of the types, a series of crosses were made to produce PA,PB,F1,F2,BC1A, and BC1B progeny. Phenotypic segregation ratios suggested the presence of two dominant alleles Crd and Cr, determining the enlarged disk and trans floret, male-sterile and enlarged trans floret, male-fertile crested types, respectively, and an unlinked dominant gene, Sp, determining the spider type. Dominance appeared to be incomplete due to the reduction of trans floret length in most Crdcr and Crcr heterozygotes compared to crested homozygotes and the appearance of the quasi-spider type among certain crested Spsp heterozygotes. A second objective was to determine the mode of inheritance of a glossy leaf type having very low numbers of bristle macrohairs (MHs) on the adaxial leaf surface compared to the wild type. Phenotypic segregation ratios suggested the presence of a dominant allele, Mhd, determining low density of adaxial bristle MHs and moderate reduction in abaxial smooth MHs. This gene was unlinked to the powdery mildew (PM) resistance gene, Pmr1, identified earlier in a parallel study. The Mhd allele appeared to be incompletely dominant in some heterozygotes. Density of leaf MHs did not affect PM resistance. A third objective was to determine the mode of inheritance of dark (brown, brown-black, black-purple, or black) color in the central disk of flowers of certain gerbera cultivars. Wild-type flowers have green-yellow, yellow-green, or light yellow central disks. Phenotypic segregation ratios indicated that dark disk color was determined by a single dominant gene, designated Dc. Dominance appeared to complete. A fourth objective was to determine the nature and inheritance of an apple-like fragrance discovered in a line of our NCSU gerbera population. The moderate fragrance exhibited was due to the emission of substantial quantities of methylbutanoic acid methyl ester (methyl-2-methyl butyrate), a compound also produced by apples. On the other hand, wild-type, non-fragrant flower types either failed to produce detectable quantities of this methyl ester or produced very low quantities of this compound. Phenotypic segregation ratios suggested that fragrance was determined by a single dominant gene, Fr.

IMPACT: 2000-10-01 TO 2005-09-30 The large breeding collection of Wolfpack Country Gerberas has been made available to some major seed companies, including Daehnfeldt and Sakata Europe. Seeds from plants of this collection have been made available to Sakata Europe and for a time to the public by Park Seed Co. The collection was developed for increased resistance to heat, powdery mildew, and crown and root rot over that currently available to the grower and nurseryman. It contains the widest variety of flower types and colors. Our addition of apple fragrant gerberas adds a new dimension to gerbera floraculture. The information gained by our genetic studies will provide the breeder with direction for designing new cultivars exhibiting various combinations of desired traits.

PUBLICATION INFORMATION: 2000-10-01 TO 2005-09-30
Kloos, W.E., C.G. George, and L.K. Sorge. 2005. Inheritance of powdery mildew resistance and leaf macrohair density in Gerbera hybrida. HortScience 40:1246-1251.

PROJECT CONTACT INFORMATION
NAME: KLOOS, W. E.
PHONE: 919-515-5781
FAX: 919-515-3355