摘要:

Excised root segments of corn were subjected to osmotic stress by immersion in solutions of mannitol before, during, or after a period of Rb absorption. Both the time course of uptake (or loss) and selectivity of uptake were studied. Stress before or during the absorption period reduced Rb absorption to 20 % or less of that of controls, whereas it had no detectable influence on the constancy and selectivity of uptake. Stress imposed following a period of Rb accumulation caused root segments to lose only slightly more Rb than controls during the first 30 min, after which rates of change were insignificant in both. Segments stressed after the Rbabsorption period retained from 70–90 % as much Rb as did the controls, even after two hours. The comparatively great quantitative difference between effect of stress on uptake and its effect on loss is interpreted to mean that the mechanism of stress‐induced reduction of ion absorption cannot be adequately explained on the sole basis of increased efflux of ions.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05979.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Tobacco plants were grown in controlled‐environment chambers with night/day temperatures of 10/15 C., 20/25 C., and 30/35 C., and with light durations of 6 hr, 12 hr, and 18 hr. Peroxidases and malate (NAD) dehydrogenases were extracted from green leaf tissue and analyzed for isozyme patterns by disc electrophoresis. A total of 18 anodic peroxidase bands were distinguishable—each alteration in a single environmental variable producing a different isozyme profile. Malate (NAD) dehydrogenase isozyme profiles resulting from each environmental condition exhibited at least four major components, but differences in daylength and temperature conditions changed the relative banding intensities and shifted migration rates of some bands. The physiological implications of these findings are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05980.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Two electrophoretically anodal peroxidase bands, designated A3 and A4, which normally develop in zymograms of incubated pith tissue of aNicotianaamphiploid, were inhibited by the inclusion of 0.10 mg indoleacetic acid (IAA) in a liter of culture medium. The visibility of the bands was not inhibited, however, if the pith was irradiated or if unirradiated pith blocks were incubated in either irradiated IAA‐containing media or in media supplemented with irradiated IAA. Irradiation inactivates IAA in media, and according to this isozyme test, damages the capability in irradiated tissue of using exogenously supplied IAA. Radiationinduced damage to IAA metabolism caused radiation‐induced peroxidase stimulation, shown in the more rapid appearance of isozyme bands A3 and A4.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05981.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Accumulated divalent cations and phosphate (P1) in isolated bean mitochondria are released by conditions which inhibit respiration, including anaerobiosis and KCN, or by conditions which divert conserved energy from divalent cation uptake. These include ATP synthesis, KTtransport in the presence of valinomycin, and the presence of the uncouplers, 2,4‐dinitrophenol and oleic acid. The results indicate that plant mitochondria are not permanent deposit sites for divalent cation and P1salts but, rather, function as temporary sequestering sites for these ions. It is suggested that mitochondria may play a role in the control of the movement as well as a regulation of the concentrations of these ions within the cell.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05982.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Six native species ofPedicularisin Mount Rainier National Park in Washington State were studied for their reproductive relationships with animal pollinators. Cinematographic and stereophotographic records revealed pollination of the nectariferousP. bracteosaandP. rainierensisby upright, nectar‐foraging queens and workers of five bumblebee (BombusLatr.) species and by inverted workers scraping pollen from anthers concealed within the corolla galea. The nectarless, rostrate flowers ofP. contorta, P. groenlandica, P. ornithorhyncha, andP. racemosawere pollinated by pollen‐foraging workers and occasional queens virbrating pollen from concealed anthers. Insect exclosure methods revealed complete absence of fruiting in the absence of insects, and pollinator collections further indicate obligate dependence of the plants upon bumblebees for their sexual reproduction. Analysis of corbicular pollen loads from pollinators suggested that pollinator species are not monolectic but that individual pollinators range from monolectic to polylectic. Measurements indicated limited correlations between lengths of corolla tubes and tongues of nectar‐foraging insects. Each nectarlessPedicularisspecies occupied a different, specific habitat, butP. bracteosaand the endemicP. rainierensiswere sympatric in part. Each species had a unique spectral reflectance pattern from the corolla. Proximity of habitats and overlap of blooming periods of allPedicularisspecies eliminate the possibility of contemporary geographic or phenological reproductive isolation. It is suggested that behavioral interactions of the plants and their insect pollinators may have been instrumental in the past in reproductively isolating these species, hybrids of which are unknown.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05983.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

The red algaCubiculosporum koronicarpisgen. et sp. nov. is described from material collected during 1968 in the Philippines. The species differs substantially in regard to its carposporophyte development from other red algae in the order Gigartinales, and a new family is created based on its unique combination of reproductive features. A single, short, connecting filament is formed between the fertilized carpogonium and a nearby auxiliary cell. The latter produces several ramifying gonimoblast filaments towards the interior of the thallus. No fusion cell is formed and the gonimoblast filaments grow inward among the cells of the central axis, form secondary connections to them, and give rise to outwardly directed carposporangial filaments that develop within peripheral chambers formed between elongating inner cortical cells. The alga is a low, clump‐forming species of well‐washed intertidal reef platforms at the one Philippine locality where it has been found. There it contributed a uniform but very minor amount to the wet weight of the standing crops that were studied during two separate seasons of the year.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05984.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Treatment ofCymbidium(Orchidaceae) flowers with 10/μl/liter ethylene for up to 78 hr induces anthocyanin formation in both gynostemia (columns) and labella (lips). After that, pigment levels decrease. During 24‐hr exposures, ethylene concentrations of 0.1, 1, and 10μl/liter cause increased anthocyanin levels in both lips and columns. Ethylene also brings about color changes in the calli and wilting of the perianth, but it does not cause straightening of gynostemia and stigmatic closure. Emasculation effects are similar to those of ethylene, whereas pollination and NAA induce anthocyanin formation and closing of stigmas, as well as swelling and loss of curvature in gynostemia. The effects of ethylene are correlated with its action in other systems.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05985.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

Experiments were performed with cultured excised primary root tips ofVicia faba‘Longpod’ to determine: (1) the proportion of meristematic cells arrested in Gl and in G2 during carbohydrate starvation, and to determine if the proportion is fixed or can be varied experimentally; (2) the effect of increased starvation on the ability of arrested cells in Gl and G2 to initiate DNA synthesis and mitosis, respectively, when exogenous sucrose was supplied; and (3) whether puromycin, cycloheximide, or actinomycin D prevented the initiation of DNA synthesis and the onset of mitosis. Microspectrophotometry of nuclear DNA and autoradiographic measurements of incorporated3H‐thymidine showed that 72 hr of starvation immediately after excision produced tissue with more than 70 % of the cells arrested in G2 and less than 30 % in Gl. If cultured for three days and then starved for 72 hr, the tissue had nearly equal numbers of cells arrested in Gl and G2. As the duration of starvation increased, the time required to initiate DNA synthesis and to divide when carbohydrate was replenished also increased. Inhibition of protein synthesis by puromycin and cycloheximide prevented the initiation of DNA synthesis and mitosis, but actinomycin D, an inhibitor of RNA synthesis, did not prevent division of cells from G2 nor DNA synthesis by cells from Gl. The experiments demonstrated that the mitotic cycle ofViciahas two major controls, one in Gl and another in G2, and that other factors determine how many cells are affected by either of these cycle controls.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05986.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

The polarity of movement of gibberellin through sections cut from near the root tips ofZea maysL. was studied, using methods like those we previously used in roots for auxin and in petioles for auxins, cytokinins, and gibberellic acid (GA‐3). One μg GA‐3 was added in a donor agar block and gibberellin activity in the receiver agar at the opposite end of the section was measured directly with a modified barley endosperm bioassay. The movement of gibberellin was away from the root tip (basipetal) and thus opposite in direction to the polarity of auxin through such root sections. The time‐course of basipetal movement was dissimilar to that for gibberellin or auxin movement through petiole sections. It took 14‐18 hr for gibberellin activity equivalent to 6 ng GA‐3 to collect in the basal receivers on roots. Apical receivers showed activity equivalent to 1.6 ng GA‐3 at 14‐18 hr. Less than 0.01 ng equivalent GA‐3 was collected from sections to which GA‐3 was not added, so the 6 and 1.6 ng were almost entirely due to the added GA‐3. These general conclusions were confirmed with an experiment using14C‐GA‐3. A decline in activity in receivers was found in some experiments at 18 hr, paralleling earlier results with GA‐3, IAA, and adenine in petioles and IAA in roots.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05987.x

出版商:Wiley    

年代:1973

数据来源: WILEY

摘要:

One application of gibberellic acid (GA3) to young internodes significantly accelerated the rate of leaf initiation and caused an increase in the number of internodes in shoots ofXanthium pennsylvanicum. The average duration of one plastochron was reduced from 3.3 to 1.9 days. The rate of growth of the GA3‐treated internodes, and also of those positioned above and below, was at least twice that of the control. It appeared that the growth substance was translocated both acropetally and basipetally from the locus of application and that it significantly accelerated the rate of stem elongation. Gibberellic acid also had a pronounced morphogenetic effect on the leaves. It induced the development of lanceolate leaves instead of typical deltoid leaves. The area and the leaf length of the treated plants were both significantly reduced. Each response may be regulated by increasing or decreasing the concentration of gibberellic acid. The induced morphogenetic changes were not permanent. A reversion to the original condition was noticeable about 8 wk after treatment.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1973.tb05988.x

出版商:Wiley    

年代:1973

数据来源: WILEY