Leaves of tomato plants grown in water culture in growth rooms were inoculated with sap from healthy tomato leaves or with sap containing tomato spotted wilt virus (T.s.w.v.). Changes in the free amino acids and amides of stems and of inoculated leaves, stem growth and infectivity were determined. Samples were analysed 5, 9, 13 and I 7 days after inoculation using two-dimensional paper chromatography.Inoculation with sap from healthy leaves, mixed with celite and sodium sulphite, caused small increases in glutamic acid, asparagine, glycine and serine in the inoculated leaves, and in glutamic and aspartic acids in the stems.' Unless otherwise stated, reference to amino acids and amides is to 'concentration' and not 'amount per plant organ'. 7 5

Bioassays on ether‐soluble acid extracts from healthy and Verticillium‐infected tomato plants, showed the presence of substances inhibiting growth of wheat coleoptiles in both healthy and infected leaves and stems, but the amounts were greater in the infected.Assays of infected stems and leaves showed increases in growth‐promoting activity expressed as indole‐3‐acetic acid equivalents (IAAe), up to 200% of those for healthy controls.Similar assays of cultures of V. albo‐atrum showed growth‐promoting activity. No acid substance capable of inhibiting the growth of wheat tissue was detected in the culture filtrate. IAA was identified by colour test with Ehrlich's reagent on chromatograms from extracts of both infected stems and fungal culture filtrates.The vertical distribution of IAAe was determined in healthy and infected plants at the eight‐leaf stage by assaying individual leaves and four stem segments separately. In healthy plants the IAAe content was greatest in the young leaves (6–8) but no gradient was observed as between leaves 1–5. In infected leaves increases over the controls were found in leaves, 1, 3 and 6 and a decrease in leaf 8.In healthy stems IAAe was highest in the distal segment and infected stems showed higher values at all four levels, with the relative increase greatest in the distal region.It is suggested that the major part of the Verticillium syndrome including petiolar epinasty, tylosis, pith hyperplasia and the formation of adventitious roots is the result of an accumulation of growth substances in infected tissue.

SUMMARYKinetin supplied to the lower surfaces of petunia leaf strips reduced the number and size of local lesions following mechanical inoculation of the upper surfaces with tomato spotted‐wilt virus' (TSWV). Glucose increased lesion production, but glucose with kinetin reduced it. Kinetin mixed with infective sap did not affect lesion production.Lesions were increased with increasing water content of leaf strip and the regression equation for the relationship is given. Treatment with kinetin after inoculation reduced lesion production over a wide range of water contents, but was most effective at high values.Kinetin inhibited virus multiplication in excised tomato leaflets only when supplied at the site of infection and caused some necrosis of veins and midribs. Treated leaflets took up more water than controls and uptake continued for 4 days.Water uptake by kinetin‐treated petunia leaf strips was less than by controls but continued for 6 days with only slight discoloration of the veins.It is suggested that the inhibitory effect of kinetin may be associated with a capacity to cause increased activity of ribonuclease in the tissues.

Tomato plants were grown to the five-leaf stage under uniform conditions in a growth room with a daily light period of 15 h. Plants were sampled at intervals through 24 h periods and the free ninhydrin-positive compounds determined in roots, bleeding sap, stems and shoots (mainly leaves), using ion-exchange column chromatography and a lithium-buffer separation system. The compounds present and their range of concentrations are given for two occasions: after illumination for 8 h and after 5 h of darkness.Data for y-aminobutyric acid (GAB), glutamic acid, glutamine, alanine, aspartic acid and ammonia are summarized graphically for all occasions and for all parts of the plant; asparagine for sap only. The data were examined for correlations between these substances for both light and dark conditions.Relative amounts of free acids were: root glutamine > glutamic and GAB > aspartic > alanine; bleeding sap glutamine > asparagine > GAB > aspartic > alanine; stem glutamine > glutamic > GAB and aspartic > alanine; shoot (leaf) GAB and glutamine > aspartic > alanine and glutamic. Patterns of change were as follows: in the root GAB and glutamic were similar and unlike glutamine; alanine did not change; in sap ammonia, GAB and alanine were parallel, glutamine was similar to these only in light; in the stem glutamine and glutamic tended to accumulate in parallel in light, but GAB did not; in the shoot {leaf) GAB and glutamine were similar except that the former accumulated more rapidly in the initial light period; glutamic acid and alanine were similar to each other but distinct from GAB and glutamine.The relatively large amounts of GAB in tomato plants and the magnitude of the changes occurring in light and darkness seem indicative of its importance as a temporary storage product for protein amino acids, but the factors controlling accumulation and utilization in different parts of the plant are unknown.

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