Transport of the cytokinin 6‐benzylaminopurine‐8‐14C in the root and shoot of intact Citrus aurantium L. seedlings was studied by “replacing” the 0.5 cm root tip with the uptake solution. The cytokinin was transported basipetally in the root and was distributed in an acropetal direction in the stem and into the leaves. Kinetic analysis of the transport for periods of up to 96 h revealed a characteristic advancing front of the label along the axis of the seedling. The estimated velocity of transport of 6‐benzylamino‐purine‐8‐14C in various regions of the intact root was 2.6 to 5.1 mm/h. The transport of 6‐benzylaminopurine was predominantly in the transpiration stream, in stelar tissues of the root. Conditions of high transpiration favored enhanced transport to the shoot and an overall greater accumulation of the label. The total accumulation of 6‐benzylaminopurine in roots of intact seedlings after 48 h of transport was 354% of that in roots of shoot‐less seedlings. Root girdling and treatment of the root with KCN did not reduce the basipetal transport of the label in the root and into the shoot. Radiochromalogram scanning of root extracts and analysis of the ethanol insoluble‐NaOH soluble fraction revealed considerable metabolic changes in the translocated cytokinin. Only 51% of the radioactivity remained in the original 6‐benzylaminopurine peak after 24 h of incubation. Two other, unidentified, metabolites were detected. It is suggested that all the factors that affect the ascent of sap are involved in the long‐distance transport of cytokinins, and that the rate and mode of transport of cytokinins from the root system to the shoot may be a major factor in the expression of their physiological activity.

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SUMMARYAn antiviral factor from virus-infected plants (AVF) was purified in an active form on SDS-polyacrylamide gels. AVF binds to concanavalin A and is partially sensitive to c~-glucosidase. It is sensitive to pronase only when incubated in conditions suitable for proteolysis of glycoproteins. Alkaline phosphatase affected the electrophoretic mobility of AVF, but did not abolish antiviral activity. AVF was insensitive to DNase, fl-glucosidase and pancreatic lipase. The AVF band obtained upon electrophoresis could be stained with Coomassie blue and by the Schiff-periodate procedure for carbohydrates. AVF is considered to be a phosphoglycoprotein with a mol. wt. of about 22000.

The transport and distribution of IAA‐2‐14C, gibberellin A3‐3H, 6‐benzylaminopurine‐8‐14C and sucrose‐14C (U) were studied in whole seedlings of Citrus aurantium L. after “replacing” the root tip with the solution of radiochemicals. All four substances were transported basipetally in the root and were distributed to the stem and leaves. The pattern of distribution of the label from 6‐benzylaminopurine was similar to that of sucrose, while a considerably larger amount of gibberellin A3 was transported to basal regions of the root, away from the tip, and into the shoot. Contrary to these three substances, the basipetal transport of IAA in the root was very low, and the majority of the label was retained in the terminal sections of the root. It is suggested that the different efficiencies at which various hormones move in the transpiration stream in the root may be an important factor in the attainment of a certain balance of hormones in the shoot.