Die Erbfaktoren beiAntirrhinum majus und ihre Bezeichnung

A Small Family ofMYB-Regulatory Genes Controls Floral Pigmentation Intensity and Patterning in the GenusAntirrhinum

“…At the higher temperatures (258C) and lower light levels typical of greenhouses in the United Kingdom, no pigment is produced in the lobes ( Figure 1I). Under the higher light but lower temperatures outside, field-grown ros dor plants have prominent pigmentation on their dorsal lobes ( Figure 1C The phenotype conferred by Venosa (Ve þ ) in A. majus involves the production of magenta anthocyanin pigment in tissue over the veins of the corolla ( Figure 1G) (Baur, 1910a;Kuckuck and Schick, 1930;Stubbe, 1966). Pigment production is limited to the inner epidermis of the petal lobes and to the inner epidermis of the corolla tube ( Figure 1H).…”

“…This arrangement of yellow (aurone) and magenta (cyanidin) pigments provides a visual target for prospective pollinating bumblebees and probably guides them to the mouth of the fused corolla (Harbourne and Smith, 1978;Penny, 1983;Lunau et al, 1996). Some natural isolates of A. majus have additional patterning, in the form of increased pigmentation in regions of the epidermis overlying the vascular strands of the petal (Baur, 1910a(Baur, , 1910bKuckuck and Schick, 1930;Stubbe, 1966). This venal pattern of pigmentation predominates on the inner (adaxial) epidermis of the dorsal petal lobes but continues into the inner epidermis of the corolla tube and, in contrast with the UV light-absorbing flavonoids, probably provides additional visual guides for the bees once they enter the corolla tubes (Thompson et al, 1972;Lunau et al, 1996).…”

“…Some mutations of these genes can give rise to patterned alleles (Coen et al, 1986;Martin et al, 1987;Coen and Carpenter, 1988;Martin and Lister, 1989), but patterned phenotypes invariably result from alleles in which the regulation of the expression of the structural gene has been affected, either through changes to the regulatory motifs of the promoters of the structural genes or through likely production of small interfering RNAs (Coen et al, 1986;Martin et al, 1987;Coen and Carpenter, 1988;Almeida et al, 1989;Martin and Lister, 1989;Robbins et al, 1989;Bollmann et al,1991;Della Vedova et al, 2005). A number of mutations that affect the activity of regulatory genes that control the expression of the structural genes of floral pigment production have also been described, including delila (del), Eluta (El), rosea (ros), Venosa (Ve), and mutabilis (mut) (Wheldale, 1907;Baur, 1910aBaur, , 1910bKuckuck and Schick, 1930;Stubbe, 1966). Mutations in the regulatory genes do not abolish pigmentation but change the pattern of pigmentation within the flowers: Delila affects pigmentation in the corolla tube; Mut affects pigmentation in the corolla lobes; Rosea affects the pattern and intensity of pigmentation in both lobes and tubes; and Venosa affects pigmentation of the epidermis overlying the veins in both lobes and tubes.…”

Floral homeotic mutations produced by transposon-mutagenesis in Antirrhinum majus.

“…The development of the fourth whorl did not usually occur in the extreme phenotype but comprised two united carpels in less severe forms. A third unlinked locus, glo, has also been described, which gives this phenotype (yon Kuckuck and Schick 1930). The phenotype carpel, stamen, stamen, carpel is conferred by the most extreme allele obtained at the ovu locus.…”

Species crosses in Antirrhinum

“…The absence or reduction of anthocyanin in seven of the last eight strains depends on the multiple allelomorph series, termed the pal series by Kuckuck and Schick (1930), one member of which is the evermutating gene. The genes causing loss of anthocyanin in one of the yellow strains have not been isolated and classified.…”