Bohme, H. and G. Scholz
The mutant chloronerva, which spontaneously arose from the variety "Bonner Beste" shows a monogenic recessive segregation. The seedlings are indistinguishable from the wildtype. Later on the intercostal areas of the leaves become yellowish white to white, the nervature remaining green. With increasing age this pattern is blotting out to some degree. The leaves of the mutant are smaller with rounded undulated leaflets of leathery consistence. Development of the root system is highly disturbed. Growth of the shoot is also inhibited, flowers are not formed (Kulturpflanze 8:93, 1960).
chln chln
__________
The mutant scion of the grafting + + develops just
normally, with normal leaves, flowers and fruits, showing only
in a later stage a newly manifested spotting of the youngest
leaves, increasing again with advancing age.
+ +
__________
The mutant stock of the grafting chln chln forms normal roots.
The axillary buds of the stock grow up to quite a normal
phenotype which in a later stage gradually starts to develop
spotted leaves with increasing clearness.
This phenomenon which we call "partially phenotypical normalization" also
proves true with graftings of L. Peruvianum and L. hirsutum as well as with
other Solanaceae examined in the course of this study, including the genera
Nicotiana, Solanum and Datura.Normalization also occurs if the mutant is provided with a water extract from the wildtype by means of vacuum infiltration, leaf sprays or sterile culture upon agar. Leaf sprays bring about the same phenotype like grafting upon the wildtype. Leaf sprays are a suitable test for chemical fractionating in order to characterize the properties of the active compound or compounds. which we call "normalizing factor." This factor is heat stable, soluble in water and ethanol but insoluble in ether, benzene, acetone and other typically organic solvents. Ash solutions are inactive. Hence the "normalizing factor" seem to be a hydrophile compound of organic nature of low or moderate molecular size. Although the site of its origin remains still unknown, it is spread all over the whole plant and seems to be a generally occurring product of plant metabolism (Kulturpflanze 9, 1961, in press).
According to recent findings, one might conclude that the iron metabolism of the mutant is drastically disturbed. Further work will be necessary to elucidate the physiological properties of the mutant as well as to isolate and identify the "normalizing factor."