A comparison of the changes in biochemistry and plastid ultrastructure during the development of green and albino genetical strains of Nicotiana tabacum

The development of highly isogenic green and albino strains of Nicotlana tabacum was coropared, A method of growing albino plants in bulk under asceptic conditions in culture was devised. This allowed greater growth than methods used by other inxrestigators. Both strains were found to show maximum growth in liquid ccnpared to solid medium. Optimum growth of both strains was obtained in modified liquid Hoagland's mediun compared to modified liquid MUK medium. The albino plant showed less growth than the green under all oondltlcns and developed only a reduced capacity for photosynthesis. The green plant was found to follow the same general pattern of changes in dry weight, protein, RNA and DNA ocntent as that of other higher plants. The albino initially contained more protein and dry weight than the green, but followed the same overall pattern of metabolism as the green plant. The nucleic acids of the albino showed a different pattern during developnent to that of the green. The albino had a lower initial DNA content which later showed a large increase after the 16th day. This large increase in DNA ocntent was followed by an increase in DNA content at the 23rd day. The increase in DNA occurred at the same time as the appearance of the third leaf with green patches. The plastids of the green plant followed a normal course of development. The albino farmed mainly vesicle-eontaining plastids and a few grana-containing plastids in the cotyledons at germination. The grana apparently degenerated as only vesicle-containing plastids wore observed in later stages of the cotyledons, the green patches of the later leaves off the albino contained both grana- and vesicle-containing plastids. A correlation between dilorophyll synthesis and grana fornatlon was established in the albino. A possible correlation between nucleic acid content and namal plastid formation was observed.