摘要:

AbstracttRNA containing N6‐(Δ2‐isopentenyl)adenosine may be precursors for the plant hormone cytokinin. To discriminate between tRNA containing and not containing cytokinin nucleotides, double labelling experiments were made by the use of [214C]‐mevalonic acid and [3H‐methyl]‐methionine. At a generation cycle of 2 h forLactobacillus acidophilusATCC 4963, the half‐lives of tRNA labelled with [3H‐methyl]‐methionine and [2‐14C]‐mevalonic acid are similar, namely 3 h. Isopentenylation of tRNA could be measured

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01628.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe growth ofDrosera rotundifoliawas studied in aseptic cultures with 17 dipeptides as the only nitrogen source. About half of the dipeptides were well or partly utilized. Compounds containing glycine, alanine, glutamic or aspartic acid are clearly more favourable than dipeptides containing proline. Arginyl‐aspartic acid (1.25 mM) promoted growth more than inorganic nitrogen (1.25 mMof NH4NO3). Glycyl‐alanine gave about the same growth response as NH4NO3. The inocules died rapidly in medium containing leucyl‐tyrosine and dipeptides containing methionine and valine were also toxic. There was usually a clear correlation between the growth‐retarding or growth‐stimulating effect of the dipeptides and the effects of their amino acid c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01629.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSix varieties of oat (Avena sativaL. cv. Stormogul II, Risto, Sol II, Selma, Sang and Pendek, arranged according to decreasing drought resistance) were cultivated under controlled conditions and exposed to water stress on 4 consecutive days. Seven‐day‐old seedlings were stressed by cooling the roots for 3 h to 1.0°C. During this treatment the leaf water potential decreased from ‐7 to ‐12 bars. Cuticular transpiration rate, total amount of epicuticular wax and amounts of some wax components (primary alcohols, alkanes, fatty acids) were determined.Unstressed seedlings of the most drought resistant variety (Stormogul II) showed the highest cuticular transpiration rate. After stress treatment the cuticular transpiration rate was most strongly reduced in this variety and at the same time it showed the largest increase in amount of epicuticular wax of the tested varieties. In Pendek and Sang, showing the least increase in epicuticular wax, the cuticular transpiration rate was only 5% lower after stress treatment.In all varieties the primary alcohol content of the epicuticular wax was slightly higher in stressed seedlings than in controls. Further, in Stormogul and Risto the content of the predominant alkanes was much lower in stressed seedlings than in controls. On the contrary, in Pendek the stressed seedlings showed a higher alkane content. In Stormogul II, Risto and Sol II the total amount of fatty acids was higher in stressed seedlings than in controls while the opposite was true in Sang.The relation between the epicuticular wax (amount and composition) and the cuticular transpiration rate is discussed as well as the possibility of using the tested parameters in a screening test for drought re

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01630.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHydroponically grown soybeans were fed15N‐enriched NaNO3at nine reproductive stages of development. The stem exudates contained excess15N in the fully reduced nitrogen fraction. The soybean nodules had high nitrate reductase activity, whereas the roots had no detectable nitrate reductase activity. Based on these results, we concluded that the nodule nitrate reductase system has the potential of contributing significantly to the nitrogen economy of the plan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01631.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe extractability of chlorophyllase is used as an indicator for the way in which the enzyme is incorporated inPhaeodactylum tricornutumphotosynthetic membranes. Whereas with various aqueous solutions no appreciable amount of chlorophyllase is washed from the membranes even after chloroform‐pretreatment. the enzyme can be extracted with aqueous solutions after practically all the lipids have been removed by means of 80% acetone.The proteins in an aqueous extract of the membranes thus treated were separated by electrophoresis on a 4% polyacrylamide gel; extraction of the active protein from several gels yielded a purified chlorophyllase solution.As with the intramembraneous enzyme, activity of purified, solubilized chlorophyllase depends upon the combined presence of MgCl2and dithiothreitol. The enzyme is inactivated upon heating at 56°C for 5 min.After SDS‐gel‐electrophoresis of an enriched extract, enzyme activity could be localized in the gels. The molecular weight of SDS‐treated chlorophyllase, or of its principal subunit, was estimated to be about 38 kilodaltons.The results are discussed in terms of the identity of prochloro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01632.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractModes of transport and metabolism of14C‐IAA and3H‐IAA in relation to morphogenesis of axillary buds in Scrophularia arguta.The main objectives of this study were to investigate the morphogenetic role of IAA on the growth and development of axillary buds. After foliar applications of radioactive IAA for 6 h on intact plants ofScrophularia argutaSol. the characteristics of auxin transport were studied by liquid scintillation counting, thin layer chromatography and microautoradiography. The main part of the radioactivity moved at a mean rate of 7 mm/h. Over long periods of transport, the tracers accumulated at the base of the axis and in the roots. The nodes were a little richer in3H or14C than the internodes. This fact seemed to be correlated with the vascular organization of this part of the stem. A very weak proportion of tracers was found in axillary buds. The radioactivity was to about 50% associated with the IAA molecule; the rest corresponded essentially to indolyl‐4‐acetyl‐l‐aspartic acid and indolyl‐3‐aldehyde. Tracers were mainly concentrated in the phloem along the whole axis and, to a lesser extent in some of the young differentiating metaxylem vessels, and in the medullary rays. No radioactivity was found in the cambial zone and in the mature xylem, nor in the parenchymas. These results support the view of an indirect role of IAA on the axillary bud growth an

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01633.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractMonochloro substituted indole‐3‐acetic acids inhibited shoot induction in tobacco tissue cultures about as much as IAA. Dichloro substituted indole‐3‐acetic acids inhibited shoot formation less. Other substituted indoleacetic acids except 5‐fluoro‐ and 5‐bromoindole‐3‐acetic acid were less active than IAA. Callus growth was quite variable and not correlated with auxin strength measured in theAve

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01634.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe influence of gamma radiation on the polarity of IAA translocation was investigated. Pieces of apple tree shoots, taken from 3‐year‐old trees, were irradiated in a dark irradiation chamber BK‐60Co source, 10 kCi. Doses from 20 to 150 krad were given. Strips of bark were peeled off both irradiated and control shoots. The middle parts of the bark strips were placed on agar blocks loaded with IAA‐1‐14C. The radioactivity of basal and acropetal segments was determined after about 20 h and results expressed as polarity quotient.It has been shown that irradiation with 20 krad (200 Gy) decreases the polarity quotient remarkably (polarity quotient of control equals 7; for 20 krad—2.9; 100 krad—1.6). The decrease in polarity results from inhibition of the basipetal translocation of IAA. Irradiated tissue shows a decrease in IAA uptake. Possible mechanisms of gamma irradiation effects on polar translocation of IAA

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01635.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe morphological changes of the shoots ofHelianthus annuuscv. Russian caused by varying periods of flooding of the roots were studied. Attention was focused on adventitious root formation and hypocotyl hypertrophy which are known to be caused by excess water around the roots in the absence of anoxia. Twenty‐four hours of flooding was found to be sufficient to cause both of these responses. Experiments involving flooding, leaf removal, shoot apical bud removal, two different light intensities, and a treatment in which only a small proportion of the roots were flooded suggested that a major factor causing the flood‐induced changes in the hypocotyl arises in the root but other factors may come from the leaves. In the longer‐term experiments other flood‐induced changes in shoot morphology were leaf epinasty, death of shoot apex, extreme chlorosis and hypertrophy of nodes and internodes. There was no apparent contribution of adventitious roots to the survival of flooded

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01636.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractGibberellic acid (GA3) increases the height ofImpatiens balsaminaunder both 8‐ and 24‐h photoperiods. The height also increases with all guanosine monophosphates (GMPs) under 8‐h photoperiods but only with 5′‐GMP under 24‐h photoperiods. GA3as well as GMPs increase the number of leaves under 8‐h but not under 24‐h photoperiods. GA3as well as GMPs induce floral buds under strictly non‐inductive photoperiods and increase the number of floral buds under 8‐h photoperiods. The floral bud initiation occurs earlier when cGMP is used in combinatio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01637.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY