Changes in the level of endogenous gibberellins and auxins in apical buds ofChenopodium rubrum L. after application of growth substances reversing the effect of (2-chlorethyl)-trimethylammonium chloride (CCC) on flowering

The application of CCC at concentrations inhibiting flowering ofChenopodium rubrum reduces the level of endogenous gibberellins in the apical buds of the plants. The effect of CCC may be reversed by appropriate concentrations of gibberellin (GA-), indole acetic acid (IAA) or kinetin. Kinetin applied to the apical bud during floral induction reduced the level of endogenous gibberellins similarly as CCC and if both CCC and kinetin were applied simultaneously their action was additive. On the other hand IAA applied under the same conditions increased the level of endogenous gibberellins and after joint application of CCC and IAA their level was the same as in untreated control plants. After application of CCC during floral induction the level of endogenous auxins did not change markedly but an active substance “x” appeared on the chromatograms of indole compounds. This substance was found also after simultaneous application of GA- and CCC but not after joint application of CCC and kinetin. If follows from our results that the same morphological phenomenon (flowering) can take place in plants considerably differing as to their level of endogenous growth substances. The ratio of different growth substances is obviously more important than the actual level of the single substances.     

Phosphorus disturbances associated with potato leafroll virus infection

Potato leafroll virus induces considerable disturbances of phosphorus metabolism in leafroll-infected potato plants. Each variety reacts differently in this respect on the infection, to some extent being dependent on the susceptibility of the respective variety to leafroll and to the season as well. In varieties particularly susceptible to leafroll as in Apta and Sieglinde there is a decrease of total P after infection. On the contrary, varieties showing medium susceptibility such as varieties Tatranka, Rita and Ambra react to leafroll infection with a considerable increase of total P. In the comparatively less susceptible variety Krasava, there is no change in the level of total P after infection. In autumn, however, a slight decrease of total P even in the medium susceptible variety Tatranka, and the less susceptible variety, Krasava, can be found. Our results shed a new light on existing controversies in literature regarding phosphorus content in leafroll-infected potato plants. When the changes in the contents of various phosphorus fractions in the infected plants are compared we can observe a tendency of lowmolecular fractions to rise. Among the different phosphorus fractions one common feature could be seen, except for the hypersensitive resistant variety Apta, namely, that the acid-soluble organic phosphates in the stems of all varieties examined, were considerably higher than in healthy stems.     

Die wirkung der β-(3-Pyridyl)-propion-und der β-(3-Pyridyl)-acrylsäure auf die Atmung der Wurzeln vonSinapis alba L.

V práci byly studovány rozdíly v ú?innosti kyseliny β-(3-pyridyl)-propionové (VIII) a β-(3-pyridyl)-akrylové (IX) v závislosti na stupni nenasycení pobo?ného ?etězce. Obě kyseliny inhibují r?st ko?ene i hypokotyluSinapis alba L. a zp?sobují inhibici sukcinátdehydrogenázového enzymového systému. Kyselina IX inhibuje zmíněný systém p?ibli?ně na dvojnásobek inhibice kyseliny VIII. Cytochromoxydázový systém z?stává témě? neovlivněn. Na základě experimen tálních výsledk? byla zp?esněna strukturní podmínka fytotoxické aktivity modelových slou?enin typu I v tom smyslu, ?e v?echny slou?eniny této struktury inhibují kromě r?stu také aktivitu sukcinátdehydrogenázového systému.     

A model for dynamics of cell division cycle in onion roots

Summary The study of the cell division cycle by means of caffeine labelling inAllium roots, at 15° C, employing intact root and decapitated roots at several levels (0.5, 1.0, 1.5, 2.0, and 2.5 mm) has shown that the number of cycles developed by the cells is constant at each meristem level. This number and the durations of the cycles are not affected by the decapitation. It is suggested that the cell cycle is controlled in the meristematic cells by an intracellular programme which would be developed throughout the meristem.However, the larger the region decapitated is, the more decreases the growth rate of the roots. The removal of the root cap (about 0.5 mm) did not modify the rate of root growth, although it blocked the geotropic response. The quiescent center is proposed as a source of auxin controlling cell elongation.     

Impatiens parviflora DC. — a natural host of cabbage black ringspot and cucumber mosaic viruses

Identification trials were carried out to determine a virus-like disease ofImpatiene parviflora DC. Two forms of foliar symptoms were observed:

1. a)
   Chiorotie and necrotic areas sometimes fallen out, leaving the leaves “shot holed”;     

Electrophoretic investigation of proteins in different root zones ofvicia faba L.

The differentiation of tissues is closely connected with the proteosynthesis. One can therfore assume that tissues with different types of cell growth (meristematic or elongation growth) and with different degrees of differentiation are different in their protein composition. In order to compare the protein composition of different plant organs, the method of disc electrophoresis on a polyacrylamide gel has been used by some authors. As compared with other methods used up to now, e. g. isolating proteins on DEAE cellulose or in Sephadex, this method does not need so much material and its resolution ability seems to be higher. It is also quicker and enables the study of several samples simultaneously. Its disadvantage is that proteins can be identified mainly by means of Rf and their quantity, measured from the intensity of staining of individual fractions in the gel, which may be misleading due to different sorption capacity of different proteins (Fri?Fri?ová 1967). None the less, it is good for comparison of protein composition of individual parts of the plant body. Different methods have been used to compare protein composition of individual growth zones in roots.Barsky,Ivanov andPushakova (1965) used luminiscence microscopy and found that in maize roots it is not possible to find substantial differences by this method.Morgan andReith (1954) arrived at similar conclusions. On the other hand,Steward et al. (1965) andMorris (1966) found qualitative differences in protein composition of different parts of pea roots using acrylamide electrophoresis. The results of the last named authors show considerable discrepancies in details, due perhaps to a different method of extraction (buffer, pH, purifying method). We have used acrylamide gel electrophoresis for investigating proteins in precisely defined growth zones of theVicia faba root.