Relationship between Floret Elongation and Pigment Synthesis in the Flowers of Carthamus tinctorius

Floret elongation and levels of precarthamin were investigatedin freshly collected flowers of Carthamus tinctorius. Accumulationof precarthamin was found to be induced at the early stagesof floret elongation. [U-¹⁴C]Acetate and [U-¹⁴C]phenylalaninewere incorporated into precarthamin in the detached floretsfrom the flower bud. The results suggest that precarthamin issynthesized via the acetate-shikimate pathway. Carthamus tinctorius L, floret elongation, pigment synthesis, precarthamin     

Metabolism of Pyrimidines in Protoplasts from Cultured Catharanthus roseus Cells

The metabolism of [2-¹⁴C]thymine, [2-¹⁴C]thymidine, [2-¹⁴C]uraciland [¹⁴C]uridine was investigated in protoplasts obtained fromsuspension cultures of Catharanthus roseus. Most of the exogenouslysupplied thymine, thymidine and uracil was degraded, and salvageof these pyrimidines accounted for 5–36 per cent of thetotal amount of ¹⁴C-labelled precursors which was metabolized.However, more than 80 per cent of the labelled uridine was utilizedfor the biosynthesis of nucleotides and nucleic acids, and therest was degraded. In contrast to the results from protoplastsof sugar cane cells in suspension culture, the data indicatethat protoplasts possess a pathway for the degradation of pyrimidines,and that the overall metabolism of these pyrimidines in protoplastsis very similar to the metabolism in the intact cells. Catharanthus roseus, madagascar periwinkle, protoplasts, pyrimidine metabolism     

INTERACTION OF GIBBERELLIN, KINETIN AND POTASSIUM NITRATE IN THE GERMINATION OF LIGHT-SENSITIVE TOBACCO SEEDS

1. The effects of gibberellin, kinetin, potassium nitrate, andtheir interactions in the germination of light-sensitive tobaccoseeds were studied. 2. Gibberellin was very effective in inducing the dark germinationof tobacco seeds, and a linear relation was found to exist betweenthe germination rate and the concentration of gibberellin ifa suitable temperature was chosen for germination. This linearrelation was, however, changed by illumination and by a raisedtemperature in the manner that the germination on lower concentrationsof gibberellin was increased by the former and decreased bythe latter. 3. Kinetin was effective in promoting the tobacco seed germinationonly when the seeds were irradiated. This light effect was,however, limited only to the longer wavelengths in the visibleregion. The red effect was found to be reversed by infra-redirradiation under the influence of kinetin. 4. The combination of gibberellin and kinetin was synergisticin promoting the tobacco seed germination both in the lightand in the dark, whereas the combination of potassium nitrateand gibberellin or kinetin was synergistic only in the light. (Received November 1, 1960; )