摘要:

The flowering response of axillary buds of seedlings ofPharbitis nilChoisy, cv. Violet, was examined in relation to the timing of apical bud removal (plumule including the first leaf or second leaf) before or after a flower‐inductive 16‐h dark period. When the apical bud was removed well before the dark period, flower buds formed on the axillary shoots that subsequently developed, but when removed just before, or after, the dark period, different results were observed depending on the timing of the apical bud removal and plant age. In the case of 8‐day‐old seedlings, fewer flower buds formed on the axillary shoots developing from the cotyledonary node when plumules were removed 20 to 0 h before the dark period. When the apical bud was removed after the dark period, no flower buds formed. Using 14‐day‐old seedlings a similar reduction of flowering response was observed on the axillary shoots developing from the first leaf node when the apical bud was removed just after the dark period. To further elucidate the relationship between apical dominance and flowering, kinetin or IAA was applied to axillary buds or the cut site where the apical bud was located. Both chemicals influenced flowering, probably by modulating apical dominance which normally forces axillary buds to

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08782.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Tobacco (Nicotians tabacum) KY14 cell cultures have previously been reported to produce capsidiol and other stress metabolites when treated with fungal elicitor or cellulase. Using a new high performance liquid chromatographic technique, we have measured the changes in sesquiterpene phytoalexins and membrane lipid classes thai occur upon elicitation of tobacco cell cultures with cellulase. Measurable levels of capsidiol and debneyol were found in the tobacco cells and in the culture medium after 8 h of elicitor treatment, with levels continuing to increase for up to 24 h. For the duration of the experiments, the levels of most of the galactolipids and phospholipids were found to decrease in elicited cells and increase in control cells. The most striking change was a rapid decrease in the level of digalactosyldiacylglycerol in elicited cells, to less than 10% of the level in control cells. Among the sterol lipid classes, the most notable changes occurred in the levels of sterol esters and acylated sterol glycosides, which increased significantly in elicited cells within 2 to 4 h after addition of cellulase, but remained unchanged in control cells. Free sterols and sterol glycosides declined slightly, while free fatty acids dropped to low levels 24 h after treatment of cells with cellulase. The present results and those of previous studies indicate that esterification of phytosterols may be a widespread response to environmental or chemical stress.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08783.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The changes taking place during fruit development in the concentration of the 3 polyamine fractions, i.e. free, perchloric acid‐soluble conjugates and perchloric acid‐insoluble bound polyamines, were analyzed in tomato fruits (Lycopersicon esculentumMill, cv. F121) induced to set by either pollination or auxin application. Before the onset of cell division, total polyamines were 50% higher in auxin‐treated fruits than in pollinated ones, most of the polyamines being found as perchloric acid‐soluble conjugates in both fruit set treatments. At the onset the level of polyamines in both fruit types was 100 times higher than during cell expansion or ripening. The highest polyamine found during cell division was perchloric acid‐soluble conjugated spermidine in both fruit set treatments. After cell division, polyamine concentration was similar in both fruit set treatments. The concentration of polyamines in the jelly was similar in pollinated and auxin‐induced fruits during cell expansion but not during ripening. At the onset of ripening there was an increase of one order of magnitude in the concentration of perchloric acid‐insoluble bound putrescine in the jelly of pollinated fruits. Polyamines were more than 5‐fold higher in unpollinated ovaries than in fruits induced to set by either pollination or auxins. It is suggested that pollinated and parthenocarpic fruits differ in their polyamine metabolism during the initial stages of development, but not after cell division. It is also suggested that polyamines undergo rapid turnover during cell division. Perchloric acid‐insoluble bound putrescine might play a role in seed form

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08784.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Although the stalk of maize (Zea maysL.) functions as a reservoir for N, little is known of qualitative changes which accompany the remobilization of N to the developing ear. SDS‐PAGE analysis revealed that certain stalk proteins were lost, whereas others were not. The removal of ears and the prevention of pollination eliminated the selective protein loss. The use of15N labelling showed that some stalk‐protein fractions turned over faster with ear development, whereas the turnover of others was unchanged or slowed. The data indicate that at least 7 proteins function as temporary storage forms of N in the stalk, and that they are degraded during the first 3 weeks after silking to provide organic N for ear developm

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08785.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Changes in the level of cytosine methylation were assessed by HPLC in mechanically stressedBryonia dioica. Rubbing young internodes. which results in growth inhibition and ethylene production, induced a rapid and transient decrease of cytosine methylation in DNA. The level of cytosine methylation was about 25% in young internodes and dropped to nearly 0% in less than 1 h before increasing to the normal level within 3 h. A decreasing gradient of DNA methylation occurred naturally along the plant, from the apex to the base. The pool of S‐adenosylmethionine was also measured in order to establish a possible relationship between ethylene metabolism and DNA methylation. The role of DNA methylation in gene regulation is discussed and different mechanisms for methylation are considere

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08786.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Semiprotoplasts were produced from suspension‐culturedAcer pseudoplatanus(sycamore maple) cells prior to cell disruption by passing them through a 60 μm nylon screen. Cell membranes from homogenates were separated by ultracentrifugation on linear sucrose density gradients. Samples were collected by gradient fractionation and subcellular fractions were assayed for membrane markers and glycosyl transferase activities. Results of standard marker assays (cytochromecreductase for endoplas‐mic reticulum. uridine and inosine diphosphatases for Golgi. and eosin‐5′‐maleimide binding for plasma membrane) showed partial separation of these three membrane types. Golgi and plasma membrane markers overlapped in most gradients. Incorporation of14C‐labeled sugars from UDP‐glucose and UDP‐xylose into ethanol precipitated polysaccharides was used to detect glucan synthases I&II (glucosyl transferases) and xylosyl transferase activities in Golgi membrane fractions. All three glycosyl transferases overlapped in fractions corresponding to both Golgi and plasma membrane markers, although peak activities for all three occurred in different fractions. More than one peak of glucan synthase I activity was found. Glucan synthase II, associated with ß‐l.3 glucan (cullose) synthesis in plasma membranes, was also detected and exhibited a 10‐fold stimulation in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08787.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Lipase (triacyiglycerol acylhydrolase, EC 3.1.1.3) in oilseeds can be associated with either the lipid body or glyoxysomal membrane and can have various pH optima and substrate specificities. There is conflicting evidence for the subcellular location of lipase in gymnosperms, and little information exists on its activity characteristics. In this report,Pinus edulis(pinyon) was found to have an acid lipase, which was associated with the lipid body fraction and the activity of which increased during germination. Active lipase from the solubilized lipid body membrane was determined by gel permeation chromatography to have a molecular weight of 260 000. Further attempts to purify the active enzyme were unsuccessful. A lipid body membrane protein of 64 kDa which increased in parallel with lipase activity during germination was isolated by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. excised, and polyclonal antibodies were made against it. Using these antibodies, active lipase was immunoprecipitated from solution, thus indicating that the 64 kDa protein is a subunit of the lipase.Pinus edulislipase had a pH optimum of ca 4.5. and it exhibited little specificity for triacyiglycerol substrates in vitro. The lipase was specific in activity against fluorometric substrates, with the highest activity against methyl‐umbelliferyl laurale. Lipase activity was inhibited by high concentrations of non‐ionic detergent. This lipid body acid lipase appears to be primarily responsible for lipid hydrolysis during pinyon germin

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08788.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Pepper (Capsicum annuumL.) plants with and without the VA‐mycorrhizal fungusGhmus deserticolaTrappe. Bloss and Menge (VAM and NVAM. respectively), were drought acclimated by four drought cycles (DA) or kept well watered (NDA). All plants were then subjected to an additional drought followed by a 3‐day irrigation recovery period. Measurements of water relations, gas exchange and carbohydrates were made at selected intervals throughout the drought cycles and recovery. To equalize growth and avoid higher P in VAM plants. NVAM plants received higher P fertilization. Consequently, similar transpirational surface and shoot mass were achieved in all treatments, but NVAM had a higher tissue P concentration than VAM plants. Plants that were either VAM or DA, but especially the VAM‐DA plants, tended to be high in net photosynthetic flux (A), A per unit of tissue P concentration (A/P), stomatal conductance (g) or leaf turgor (Ψp) during high environmental stress or recovery from stress. During this time, NVAM‐NDA plants had low A. A/P and leaf chlorophyll, but high soluble carbohydrate concentrations in their leaves. All VAM and DA plants had some osmotic adjustment compared to the NVAM‐NDA plants, but VAM‐DA plants had the most. Osmotic adjustment was not due to accumulation of soluble carbohydrate. The high turgor, A and g in the VAM‐DA plants during and following environmental stress indicated superior drought resistance of these plants; however, osmotic adjustment was only apparent during recovery and cannot account for the observed drought resistance during environmental stress. Drought resistance of VAM‐DA plants was not attributable to high leaf P concentration or confounded by differences in plant transpi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08789.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Cellular responses of two rapid‐cyclingBrassica species. B. napusandB. carinata, to seawater salinity were characterized to determine whether callus showed a tolerance similar to that of whole plants. Callus was initiated from the leaves of 7‐day‐old seedlings ofB. napusandB.carinataand then subcultured with two different levels of seawater salinity (2.3 and 5.2 g l−1Instant Ocean. Aquarium Systems, Inc. Mentor. OH, USA) for 14 days. Callus growth of both species was reduced by seawater salinity. Based on the percentage of the reduction in the relative fresh weight gain.B. napuswas more salt‐tolerant thanB. carinata. consistent with the response of whole plants of the same species to seawater salinity. Seawater salinity caused changes in the concentrations of Na, K. Ca, Mg and Cl in bothB. napusand B.carinata. The growth expressed as the percentage of control was significantly (P = 0.05) positively correlated with the concentration of Ca. and K/Na and Ca/Na ratios. It was also negatively correlated (P= 0.01) with the concentrations of Na. Cl and Mg. In comparison withB. carinala. the salt‐tolerant species,B.napus, showed a small reduction in the concentrations of Ca and K in the salt‐stressed plants relative t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08790.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Hydroponically grown pea plants (Pisum sativumL., cv. Kleine Rheinländerin) and barley seedlings (Hordeum vulgareL., cv. Gerbel) were fumigated for several days with 1 or 2 μl l−1SO2. Both species accumulated sulfate during fumigation, although the nutrient medium lacked sulfate. In pea, SO2‐dependent sulfate accumulation in different plant parts accounted for 60 percent of the SO2sulfur which, as calculated from a determination of boundary and stomatal flux resistances had entered the leaves. Up to 55% of the air‐borne sulfate was translocated from pea leaves to roots during the period of fumigation, but no or only little sulfate was excreted into the nutrient solution. In contrast, barley retained sulfate in the leaves, and sulfate translocation from shoot to the root system could not be observed. In both species, protons were excreted by the roots. In fumigated plants, proton loss was higher than in untreated controls in pea, but not in barley. In pea, SO2‐dependent proton loss into the medium accounted for up to 50% of the sulfuric acid formed from SO2. Proton excretion was strongly dependent on potassium availability in the nutrient medium. Cation uptake by the plants during fumigation was sufficient to compensate for proton loss, suggesting proton/cation exchange at the interface between root and medium. We conclude that by oxidation to sulfuric acid, plants are capable of detoxifying SO2taken up by the leaves. Depending on plant species, either both protons and sulfate anions can be exported from the leaves, or the proton load on leaf cells can be relieved by proton/cation exchange at the plasmalemma. Finally, the problem of airborne plant acidification may be solved by proton/cation exchange at the level of roots. The burden of acidification is then shifted from the plant to the nutrient medium. Appreciable amounts of sulfate can be excreted neither by pea nor by barl

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1993.tb08791.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY