ANTHOCYANINS AND GENETICS 165 



Dendrobium. Pigmented (anthocyanin) flower dominant to albino. 

 Hurst (596). 



Digitalis purpurea. Keeble, Pellew & Jones (542) made certain 

 observations on the inheritance of anthocyanin in flowers of this 

 species. The plants used were: 



1. White with yellow spots (mmddww). 



2. White with red spots (MmddWw). 



3. White with red spots (MMddWw). 



4. Purple with red spots (MmDdww). 



5. White with purple flush and red spots (???). 

 Colour is due to the factor, M, producing magenta sap. Absence 



of M gives a recessive white. A deepening factor, D, is dominant to 

 M and changes it to purple. The colour may be inhibited by a dominant 

 factor, W, so that the corolla is white except for red spots. The spots 

 on the corolla are always present. In recessive whites they are brown 

 or yellow: in magenta and dominant whites they are red. They 

 depend on the presence of the factor M and they are not inhibited by W. 



Saunders (563) confirms the results of Keeble, Pellew & Jones 

 for the inheritance of spot colour. It is stated that white-flowered 

 plants with red spots may either breed true, or give a mixture of whites 

 with red spots (dominants) and white with greenish-yellow spots 

 (recessives) according as they are of pure-bred or cross-bred parentage. 

 Coloured flowers may vary from deep purplish-red to white with a faint 

 flush. The white-flowered plants with red spots frequently become 

 tinged as they get older. 



Geum. De Vries (498) mentions the inheritance of anthocyanin in 

 hybrid from the cross of type (yellow plastids plus anthocyanin) by 

 yellow (plastids) variety. 



Gossypium. Balls (515, 523) working on Egyptian cotton recognised 

 the following pairs of Mendelian characters which are connected with 

 anthocyanin : 



Full red spot on the leaf and faint spot. 



Large purple spot on the petal and no spot. 



The red spot on the leaf is due to the development of anthocyanin 

 in the epidermal and sub-epidermal cells of the petiole at the point 

 where it divides into the leaf-veins. Crosses of spotted with spotless 

 give spotted F 1? but the intensity of colour in the spot is less than in 

 the spotted parent. In F 2 the heterozygote spot can be distinguished 

 from the homozygote. In the case of flower spot, the homozygote 

 has a large purple spot, the heterozygote a small purple spot. 



