摘要:

Winter hardening of first‐year black spruce [Picea mariana(Mill.) B.S.P.] seedlings was studied by assessing a number of morphological and physiological changes under three hardening regimes: 1) early removal (ER), in which seedlings were exposed to natural daylengths and low ambient temperatures outside. 2) extended greenhouse culture (EG), in which seedlings were exposed to natural daylengths and warm temperatures, and 3) short day (SD), in which seedlings were exposed to short daylengths and low ambient temperatures outside. Measurements included needle primordia initiation, embryonic shoot volume, terminal bud mitotic index, embryonic shoot average cell volume, and shoot tip frost hardiness. EG seedlings formed buds containing 4 times as many needle primordia as ER stock. Embryonic shoot volume increased with number of needle primordia initiated, until late in the hardening period, when significant reductions in meristem volumes of SD and EG stock were observed. Frost hardiness increased sooner in seedlings which set bud in response to short days, but SD treatment did not result in significantly greater frost hardiness at the end of the trial. Frost hardiness was correlated with mitotic index of the embryonic shoot. Cell size in the embryonic shoot declined in seedlings of all treatments during hardening, however, EG seedlings had significantly lower cell volumes by the end of the trial in comparison to ER and SD seedling

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05444.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Growth, peroxidase activity and isoperoxidase pattern were studied during the growth cycle of 3 cell suspension lines of carrot (Daucus carotaL.), an embryogenic, a non‐embryogenic and a habituated cell line. Isoelectric focusing of extracted proteins on agarose gels revealed the isoperoxidase pattern of the embryogenic line to include, among other differences, an isoperoxidase with a pl of pH 7.0 when grown under conditions stimulating embryogenesis. This isoperoxidase (P7.0: EC 1.11.1.7) was present between days 2 and 6 after subculturing, and this period correlates well with the early stages of somatic embryogenesis. This isoenzyme showed very low activity in the non‐embryogenic and habituated cell suspension lines as well as in the embryogenic cell line in the presence ofDaucus carota, 2,4–dichlorophenoxyacetic acid. P7.0 could probably be used as a biochemical marker of somatic embryoge

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05445.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effect of a weak acid (butyric acid) on the germination of seeds ofPhacelia tanacetifoliaBenth. (cv. Bleu Clair) has been studied. Butyric acid inhibited the early phase of germination, and the inhibition was correlated to the amount of the per‐meant undissociated form present in the incubation medium. The inhibition by butyric acid in the dark was also correlated to a decrease of dark fixation of CO2and to a more pronounced decrease in malic acid levels during the early phase of germination; suggesting that the uptake of the uncharged form of this weak acid was followed by a release of H+ into the cytoplasm, leading to a decrease in its pH. The inhibitory effect of butyric acid in the dark on many metabolic events (rise in respiratory activity, levels of reducing sugars, glucose‐6–phosphate and malic acid, dark CO2fixation, transport activities and macromolecular synthesis) appeared similar to the one of light. Fusicoccin (FC), which directly stimulates the H+pump at the plasmalemma level, ameliorated the effect of butyric acid, as well as that of light, on germination. The bulk of these data is interpreted as suggesting that the mechanism of light inhibition of germination ofPhacelia tanacetifoliaseeds might be the consequence of a general block of metabolic reactivation due to the presence of an unfavourable (acidic) cytoplasmic pH; which might be explained with the lack of the phytochrome‐dependent activation of the H+pump at the plasmalemm

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05446.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Glutathione reductase (EC 1.6.4.2) was purified from Scots pine (Pinus sylvestrisL.) needles. The enzyme had a specific activity of 3.65 μkat (mg protein)−1, and the apparent molecular weight of the polypeptide was 59 kDa. Sulfhydryl‐modifying reagents such as N‐ethylmaleimide and iodoacetate inactivated the enzyme in the presence of NADPH. Oxidized glutathione protected the enzyme against this inactivation. NADPH inactivated the enzyme by ca 35% within 5 min. High concentrations of hydrogen peroxide (32 μM) had no effect on enzyme activity. High concentrations of sulfite (5 μM) inhibited the enzyme but low concentrations (60 μM) did not affect the activity. The Km for oxidized glutathione and NADPH was 28 and 1 μM, respectively. The pi was 4.7 and the amino‐acid composition was similar, with minor exceptions, to that of glutathione reductase obtained from rice embryos, human erythrocyte

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05447.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

This study examined the question: do bacteroids within the nodule have the ability to produce indole‐3–acetic acid (IAA) and does their IAA‐producing ability correlate with the amount of IAA contained in the nodule? Soybean [Glycine max, (L.) Merr. cv. Tracy] plants were inoculated with a wild‐type clone ofBradyrhizobium japonicum, 1–110 known to form nodules that contain low amounts of IAA or with 5‐methyltryptophan‐resistantB. japonicum, clones known to form nodules that contain large amounts of IAA. The resulting bacteroids were isolated from the nodules and examined for their ability to synthesize IAA. IAA production by wild‐type bacteroids was 90 pmole IAA (mg protein)−1h−1and IAA production by mutant bacteroids was 620 to 690 pmole IAA (mg protein)−1h−1. These data indicate that bacteroids from high IAA‐containing nodules have an enhanced ability to produce IAA, implying that bacteroid‐produced IA

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05448.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The levels of tubulin protein in developing cotton (Gossypium hirsutumL. cv. Stoneville 825) fibers were measured from 8 to 28 days post‐anthesis using commercially available monoclonal antibodies against alpha‐ and beta‐tubulin. As the monoclonal antibodies against alpha‐ and beta‐tubulin were prepared from yeast tubulin and chick brain tubulin, respectively, indirect immunofluorescence microscopy was used to establish that the two monoclonal antibodies recognized microtubule structures in cotton fibers. Western blots of electrophoretically separated proteins in crude extracts of cotton roots and fibers showed that single polypeptides with the expected apparent molecular weight for tubulin subunits were recognized by the antisera. An enzyme‐linked immunosorbent assay was used to quantify tubulin levels. From 10 to 20 days post‐anthesis the level of tubulin protein increases approximately three‐fold. After 20 days post‐anthesis, the amount of tubulin relative to total fiber protein reaches a plateau or decreases slightly. The rapid rise in tubulin is correlated with the elongation of the fiber and an increase in ce

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05449.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The promotion of root growth by capillarol [methyl 3‐(3‐methylbut‐2‐enoyl)‐4‐hydroxycinnamate] and related phenolic compounds were studied in relation to structure‐activity relationships. Concentrations above 5 × 10−5Mcapillarol stimulated the root growth of rice (Oryza sativaL. cv. Tanginbozu and cv. Nihonbare) seedlings to about 180% of the control value at 5 × 10−4M. Capillarol had no promotive and hardly any inhibitory effect on the growth of the second leaf sheath. Capillarol promoted the root growth also in seedlings of lettuce (Lactuca sativaL. cv. Grand Rapids) to ca 150% of the control value at 5 × 10−4M. The free acid form of capillarol (capillaric acid) was about as effective as capillarol.Para‐hydroxy‐ but notm‐methoxy‐ substituted cinnamic acid, phenylpyruvic acid, phenylacetic acid and amino‐hydrocinnamic acid could stimulate root growth, butp‐hydroxybenzoic acid was inactive. It is concluded that the important structural requirements for high root growth‐promoting activity of phenolic compounds are the hydroxyl group substitution at the C‐4 position of the benzene ring, and the propanoic or propenoic acid side chain at the C‐1 position. A possible mode of the action of capillarol on root gro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05450.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The influence of nicotianamine (NA) on formation and elongation of adventitious roots in hypocotyls of de‐rooted NA‐less mutant seedlings ofLycopersicon esculentumMill, was examined in relation to the iron supply [ferric N‐N'‐ethylenediaminedi‐(2‐hydroxyphenylacetate) (FEDDHA), ferric ethylenediaminetetracetate (FeEDTA), ferric N‐(2‐hydroxyethyl)‐ethylenediaminetriacetate (FeHEDTA, Fe‐citrate and FeCl3] in the nutrient solution. The initiation of root primordia in hypocotyl cuttings was independent of NA and occurred with about the same frequency in both, mutant and wild‐type. In the mutant the development of primordia to adventitious roots was blocked at all iron sources used, except FeEDTA. Addition of NA (5x 10−6to 2 × 10−5M) to the rooting medium resulted in a fast growth of adventitious roots in mutant cuttings with all iron sources tested. Rooting of wild‐type cuttings was independent from NA application and iron sources. We suppose that NA is involved in the intracellular transport of iron. Its function is possibly linked with chelation

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05451.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Photosensitivity of germination of white clover (Trifolium repensL. cv. Podkowa) seeds was studied under water deficit (low water potential) conditions at 25°C. The seeds showed negative photoblastism, which was most pronounced at ‐0.03 MPa polyethylene glycol solution. Inhibition was observed at two different wavelength bands with maxima at 660 nm (R) and around 730 nm (FR). Red light acted identically to white light (maximum inhibition ca 50%). The effect of far‐red illumination was less inhibitory (20–30%). The photoresponse required long illuminations (3 h exposures); saturation level was at 0.1 W m−2, independently of the light quality. White clover seed germination showed no reversibility of the effects of R and FR light. Prolonged illumination with R and FR increased the inhibition, and intermittent illumination had a higher effect than a continuous one. It was concluded that the photoinhibition of germination of seeds ofTrifolium repensinvolves a reaction dependent on the rate of phytochrome interconversion, a property that is characteristic for the high irradiance

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05452.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The nucleotide sequence of a 5.7 kbp region of pea (Pisum sativumL.) chloroplast DNA containing thepsbBoperon and a putative promotor and termination site has been determined and compared to the corresponding sequences from spinach, maize, tobacco and the liverwortMarchantia polymorpha.The organization of the operon is the same as for the other species, i.e.psbB/psbH/petB/petD.These genes code for a 56 kDa chlorophyll‐binding photosystem 2 (PS2) polypeptide, an 8 kDa PS2 polypeptide, cytochromeb6(24 kDa) and subunit 4 (18 kDa) of the cytochromeb6/fcomplex. Two short and oppositely directed putative polypeptide genes are located betweenpsbBandpsbH.ThepetBandpetDgenes contain introns of 818 and 715 bp, respectively. The psbB, petB and petD proteins encoded in the pea operon are 89–98% homologous to those from the other species, while the pea psbH protein has a homology of 65–96% to that of the other species. The nucleotide sequences of introns and intergenic regions from the higher plants are 60–70% homologous. From comparisons with spinach sequences we conclude that the primary pea transcript probably has a length of 560

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05453.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY