Effect of growth regulators on overcoming the light inhibition on germination ofCucumis anguria L.

The effects of some growth regulators on the dark-germinating seeds ofCucumis anguria have been investigated. GA₃, 6-BA and ethrel strongly promoted the germination of seeds kept in white light. GA₃ had no effect in counteracting the far red effect, but did counteract partially the blue light. Ethrel partially counteracted both the far red and blue light effect. No interaction could be found between red light and GA₃ or 6-BA.     

Mechanism of photosystem-I photoinhibition in leaves ofCucumis sativus L.

It was recently shown that the site of photoinhibition in leaves of Cucumis sativus L. at low temperatures is Photosystem I (PSI), not PSII (I. Terashima et al. 1994, Planta 193, 300–306). In the present study, the mechanisms of this PSI photoinhibition in vivo were examined. By lowering the photon flux density during the photoinhibitory treatment of leaves at 4°C for 5 h to less than 100 mol·m^–2s^–1, we were able to separate the steps of the destruction of the electron-transfer components. Although P-700, the reaction-center chlorophyll, was almost intact in this low-light treatment, the quantum yield of the electron transfer through PSI and photochemically induced absorption change at 701 nm were markedly inhibited. This, along with the results from the measurements of the light-induced absorption changes in the presence of various concentrations of methyl viologen, an artificial electron acceptor, indicates that the component on the acceptor side of the PSI, A₁ or F_x, is the first site of inactivation. When the photon flux density during the treatment was increased to 220 mol·m^–2s^–1, the destruction of P-700 itself was also observed. Furthermore, the partial degradation of the chlorophyll-binding large subunits was observed in photoinhibited leaves. This degradation of the subunits was not detected when the treatment was carried out under nitrogen atmosphere, the condition in which the electron transfer is not inhibited. Thus, the photoinhibitory processes in the reaction center of PSI go through three steps, the inactivation of the acceptor side, the destruction of the reaction-center chlorophyll and the degradation of the reaction center subunit(s). The similarities and the differences between the mechanisms of PSI photoinhibition and those of PSII photoinhibition are discussed.Abbreviations DAD 2,3,5,6-tetramethyl-p-phenylenediamine - LHCI, LHCII light-harvesting chlorophyll-a/b proteins associating with photosystems I and II, respectively - PFD photon flux density We are grateful to Dr. I. Enami (Department of Biology, Faculty of Science, Science University of Tokyo) and Drs. H. Matsubara and H. Oh-oka (Department of Biology, Faculty of Science, Osaka University) for generous gifts of antisera used in the present work. We also thank A. Aoyama for technical assistance. This work was partly supported by the grants from the Ministry of Education, Science and Culture, Japan.     

Gibberellin biosynthetic pathway and the physiologically active gibberellin in the shoot ofCucumis sativus L.

[²H₂]Gibberellin A₂₄ (GA₂₄) and [²H₄]-GA₉ were applied to the apices of normal-type cucumber (Cucumis sativus L. cv. Yomaki) seedlings treated with uniconazole, an inhibitor of GA biosynthesis. The metabolites from these feeds were identified by full-scan gas chromatography-mass spectrometry (GC-MS) to confirm the conversions of [²H₂]GA₂₄ to [²H₂]GA₉ and of [²H₄]GA₉ to [²H₄]GA₄. The results show that GA₄ is biosynthesized from GA₂₄ via GA₉. In a cucumber hypocotyl elongation bioassay using cv. Yomaki, prohexadione (DOCHC), an inhibitor of 2-oxoglutaratedependent dioxygenase, inhibited the hypocotyl elongation caused by application of GA₉, while DOCHC enhanced the elongation caused by application of GA₄. These results indicate that GA₄ is a physiologically active GA and that the activity of GA₉ is due to its conversion to GA₄ in cucumber shoots.     

Morphogenetic effects of various growth substances on the cotyledonary stomata of brinjal and tomato

The effect of different growth substances on the development of normal and abnormal stomata are presented. Anomocytic, paracytic, anisocytic and stoma with a single subsidiary cell are observed. Abnormal developments like persistent stomatal cells, degeneration of guard cells, unusual thickening, unequal guard cells, single guard cells and size and shape of the pore are noticed in various growth substances. The growth substances also affect the stomatal frequency, stomatal index, epidermal frequency and size of guard and epidermal cells in both the plants. The highest meristematic activity is found in MOR 100 ppm in brinjal and in GA 25 ppm in tomato. The largest size of stomata is found in COL 25 ppm in brinjal and in MH 50 ppm in tomato. The same growth substance responds differently in the two plants.     

Action of cytokinins and anticytokinins on cotyledonary bud growth ofLycopersicon esculentum MILL

The action of two anticytokinins, 3-methyl-7-n-pentyl-aminopyrazolo[4,3-d] pyrimidine and 4-cyclopentylamino-2-methylthiopyrrolo [2,3-d] pyrimidine on the zeatin and 6-benzylaminopurine induced lateral bud growth ofLycopersicon esculentum Mill. cv. Fireball seedlings was studied. Bud growth stimulation by 0.1 mM zeatin was not overcome by application of anticytokinin at concentrations of 0.01 to 1.0 μ 24-h after zeatin application. However, application of 0.1 μM of anticytokinin 24-h before 0.1 mM zeatin caused a significant enhancement of bud growth. A simultaneous application of 1 mM anticytokinin and 6-benzylaminopurine or concurrent with young leaves excision significantly reduced bud growth.     

Observations on the effects of morphactin EMD 7301 and EMD 7311 on the number,size, morphology and ontogeny of cotyledonary stomata ofAbelmoschus esculentus moench

Stomata on the cotyledons of Morphactin EMD 7301 and EMD 7311 treated seedlings may be anisocytic, anomocytic, paracytic, diacytio, transitional forms and haplocytic. In spite of this diversity, the most frequent type is anisocytic on both surfaces. The stomatal ontogeny may bo perigenous, mesogenous and mesoperigenous. Morphactin EMD 7301 and EMD 7311 increase the size of cotyledons in all concentrations accompanied by an increase in the number of stomata on the adaxial surface in 100, 150, 250 ppm of EMD 7301. The effect of morphactin is promotive to the size of stomata in all concentrations, but it retards the stomatal density and number of epidermal cells. This may be due to an increase in the size of the epidermal cells. The substrates, however, have no effect on the morphology and ontogeny of the stomata; probably they are inherent chracters.     

Structure,ontogeny and taxonomic significance of trichomes and stomata in some Capparidaceae

The present work embodies epidermal structure, structure and ontogeny of stomata in five genera embracing sixteen species of the Capparidaceae namely Cleome (8 species) Capparis (5 species), Cadaba (1 species), Crataeva (1 species) and Maerua (1 species). The epidermal cells are polygonal, isodiametric or elongated arranged irregularly, with evenly or unevenly thickened, sinuous, straight or arched anticlinal walls. Two main types of trichomes: glandular (four types) and eglandular (five types) are noticed. The stomatal types include cyclocytic, triacytic, staurocytic, tetracytic, anomocytic, anisocytic, paracytic and with a single subsidiary cell. The ontogeny of stomata with a single subsidiary cell is perigenous or mesoperigenous, of paracytic mesoperigenous or mesogenous, of anisocytic is mesoperigenous or mesogenous, while that of the other types is perigenous. Abnormalities observed are: single guard cell; aborted guard cells; complete or incomplete division of guard cells; contiguous stomata; giant stomata and cytoplasmic connections. The present observations do not support the separation of Cleomaceae from the Capparidaceae.     

Observations on the structure and ontogeny of stomata and trichomes on developing and mature pericarps ofCassia occidentalis L

Paracytic, anisocytic, anomocytic, transitional forms, tetracytic, cyclocytic stomata and partly and completely amphicyclic forms are found, often on the same surface, in nine combinations. The most frequent type is paracytic. A few morphological variations in the basic types and eight types of abnormalities in stomata are recorded. The stomatal ontogeny may be mesogenous, mesoperigenous or perigenous. Trichomes are multicellular glandular club-shaped and unicellular eglandular. The taxonomic significance of stomata is indicated.     

Structure and development of stomata on the primary root of Ceratonia siliqua L

Stomata of various sizes are produced on the primary root of Ceratonia siliqua L. Most are generated during embryogenesis, prior to seed desiccation. They can be detected on the dry embryo in a wide zone just above the root tip. Initially, large stomata are formed. These have the ability to induce divisions of their neighbouring cells, creating particular cell patterns around them. Later, small perigenous stomata are generated. As the root grows following seed germination, the stomatal zone overlaps with that of the root hairs. Although root stomata of C. siliqua undergo a structural differentiation that seems almost identical to that of the elliptical stomata formed on leaves, they are unable to move and remain permanently open. Polarizing microscopy of fully differentiated stomata and young stomata at the stage of stomatal pore formation revealed deposition of radial cellulose microfibril systems on their periclinal walls. However, these systems were less developed than those on leaf stomata, a feature that might be responsible for their inactivity. Besides, plastids of the root guard cells (GCs) do not differentiate into chloroplasts but function solely as amyloplasts. Root stomata have a short life span. During rapid and intense root growth, GCs cannot keep pace with the elongation of their neighbouring rhizodermal cells. They therefore split in their mid-region, transversely to the stoma axis. The two parts of the transversely torn stoma are dragged apart and a large opening is formed on the root surface, just above the substomatal cavity. The root stomata, together with these openings, may facilitate increased gaseous exchange during respiration and/or an increased transfer of some nutrients and water in the rapidly growing primary root.     

萝卜对土生空团菌菌丝生长的影响

纯培养条件下, 测定了十字花科植物萝卜(Raphanus sativus L.)种子、幼苗、根系分泌物及幼苗提取物对土生空团菌(Cenococcum geophilum Fr. (Cg))菌株CgSO1、CgSB2、CgO5、SPOP2 和Cg5#菌株生长的影响。结果表明供试Cg菌株与萝卜种子共培养, 或将萝卜根系分泌物和幼苗提取物加入到培养基中, 均促进了Cg菌丝生长。高温灭菌处理使萝卜根系分泌物和幼苗提取物对Cg菌株的促生作用更强, 而高温灭菌后的萝卜幼苗段对菌株生长影响不大。其中经高温灭菌处理的幼苗水提取物对5菌株的促生作用最大, CgSO1、CgSB2、CgO5、SPOP2和Cg5#每菌落的菌丝干重分别达到: 54.8、45.8、63.9、41.2和50.5 mg。     

Observations on the cotyledonary and hypocotyledonary stomata and trichomes in some Caesalpiniaceae with a note on their taxonomic

The structure and ontogeny of stomata on cotyledons and hypocotyls and the trichomes on hypocotyl are accounted for in eighteen species of Caesalpiniaceae. Trichomes are eglandular, bi- rarely tri-celled, smooth walled or walls wavy with cuticular striations or tubercles. Anomocytic, haplocytic, paracytic, diacytic, transitional, tetracytic, tricytic and cyclocytic stomata occur in different combinations even on the same surface of the cotyledon. In all, there are fourteen combinations. Inspite of the diversity, the most frequent type is anomocytic in most of the species and paracytic in some species of Cassia and Delonix (abaxial) but rarely it is haplocytic or anisocytic. In hypocotyls it is anomocytic. Ontogenetically anomocytic, tetracytic and cyclocytic stomata are perigenous, whereas other types are mesogenous or mesoperigenous. There is an increase in the number of subsidiary cells by their division or the neighbouring perigenes assuming their shapes. About eight such types are described. A pair of stomata has a common subsidiary cell. Twelve types of guard cell and stomatal approximation abnormalities are described. A range in the number, size and shape of the nuclei in guard cell are recorded. Megastomata (giant stomata) are observed in Parkinsonia and Tamarindus. The taxonomic significance of the stomata is also discussed.     

Study on in Vitro Regeneration of Style-Stigma-Like Structure in Crocus sativus L.

Effects of age and variety of explant as well as of exogenous hormones on regeneration of style-stigma-like structure in vitro were observed in saffron. (1) Explants excised from stalk, perianth, anther, ovary, style and stigma showed different reactions in vitro, only young perianth and style could regenerate the style-stigma-like structures; (2) Age of the perianth explant had obvious effect on induction frequency, and the explants excised from an inflorescence of 24mm in length showed the highest frequency (37.5%) and (3) Experiments on exogenous hormones made clear that supplement with K 5mg/L and NAA 4mg/L was advantageous to regeneration of style-stigma-like structure. Induction frequency reached 35.3%. Supplement with 6-BAP 7mg/L and NAA 9mg/L could promote the formation of stigma like structures.     

Morphoregulatory effect of plant growth regulators on Hypericum perforatum L. Seedlings

The morphogenetic response of Hypericum perforatum seedlings to different auxin and cytokinin concentrations was studied. A stimulation of the concentration-dependent rooting ability was observed under the influence of indole-3-acetic acid and indole-3-butyric acid. Rooting was not enhanced by the effects of 2,4-dichlorophenoxyacetic acid and 1-naphtaleneacetic acid. Differentiated roots were isolated and cultured in liquid media with the same combination of growth-promoting auxins. Chromosome counts in root tip cells after long-term cultivation indicated a high degree of chromosomal instability. Multiple shoot formation occurred under the influence of 6-benzylaminopurine and kinetin. Adenine and 6-(γ,γ-dimethylallylamino)-purine did not stimulate shoot differentiation. No differences in the morphogenetic response to auxins and cytokinis were detected between diploid and tetrapoloid plants.     

Effect of seaweed extracts and plant growth regulators on high-frequency in vitro mass propagation of Lycopersicon esculentum L (tomato) through double cotyledonary nodal explant

An efficient and reproducible two-step in vitro propagation system for tomato (Lycopersicon esculentum) was developed by using the combinations of seaweed biostimulant (Gracilaria edulis and Sargassum wightii) extracts and plant growth regulators (PGRs). Double cotyledonary nodal (DCN) explants of Co-3 cultivar were initially cultured on Murashige and Skoog (MS) and Gamborg’s medium (B5) containing thidiazuron (TDZ) and 6-benzylaminopurine (BA); the best responding cytokinin was tested in combinations with different auxins (NAA, IAA and IBA), and seaweed extracts (G. edulis and S. wightii) of about basal MS medium +10–70% was used for shoot proliferation. The best organogenic culture response was obtained on MS medium fortified with 1.5 mg L^?1 TDZ and 1.5 mg L^?1 IBA. Up to 24 shoots per explants were formed at an optimal duration of exposure to 35 days. Mini shoots of about 3–4 cm were transferred to medium supplemented with MS + iP, MS + zeatin, MS + G. edulis and MS + S. wightii at different concentrations. High frequency of shoot elongation was observed in the medium supplemented with 30% G. edulis (15.2 cm), and profuse rooting was observed in the medium supplemented with 50% S. wightii of about 16.1 cm. Shoot elongation and rooting were observed in the medium supplemented with seaweed extracts. The plantlets were transferred to the plant growth chamber (70% of relative humidity and 9 light cycles) and maintained in it for a week, and then they were transferred to a greenhouse condition. The plant growth chamber to green house transferred plantlets showed an increase in the survival rate from 70 to 85%. Thus a two-step regeneration protocol was developed in this study with a combination of seaweed extracts and PGRs, which provides a basis for the production of transgenics with high frequency and survivability of tomato plants.     

The action of the testa upon the germination of seeds ofCucumis anguria L.

In negatively photoblastic seeds of Cucumis anguria L. the scarification of micropyle overcame the inhibitory effect of “white light ”, although far-red radiation inhibited the germination in both intact and scarified seeds. The moistened testa powder transmitted more far-red than red radiation. Thus the testa could act as a filter of radiation and maintain a high far-red/red ratio at the photosensitive site of the embryo, which must be localized near the micropyle.     

菌根化育苗对大棚黄瓜生长发育和果实品质的影响

以Glomus versiforme （GV）、Glomus mosseae（GM）和Glomus intraradices（GI）3种丛枝菌根菌及其混合菌种GM+GV、GM+GI、GV+GI和GM+GV+GI接种黄瓜幼苗,进行菌根化育苗,研究菌根化育苗对黄瓜的生长发育、产量和品质的影响.结果表明,接种的丛枝菌根菌均能与黄瓜幼苗根系形成菌根,侵染率高达41.74%～55.69%.其中,GV、GM、GM+GV、GM+GV+GI 和GV+GI是黄瓜的优势菌种,与对照相比,壮苗指数提高了58.14%～123.6%,前期产量增加了21.71%～37.87%,总产量增加了19.72%～34.41%.接种GM+GV和GV+GI处理可显著地提高黄瓜果实中Vc的含量,分别比对照提高了22.84%和21.95%;接种GV、GV+GI和GI处理可显著提高黄瓜果实中可溶性糖含量,分别比对照提高了13.79%、10.20%和8.25%;接种GV和GM+GI处理黄瓜果实中的氨基酸含量,分别比对照提高了47.66%和23.19%,蛋白质含量提高了17.67%～34.79%.     

NO and IAA Key Regulators in the Shoot Growth Promoting Action of Humic Acid in Cucumis sativus L.

Previous studies have reported that a purified sedimentary humic acid (PHA) was able to increase the concentration of nitric oxide (NO), indole-acetic acid (IAA) and ethylene in cucumber roots. Here, we investigated if these effects are functionally related to the ability of PHA to improve shoot growth. The effect of specific inhibitors of NO, IAA and ethylene functionality and signaling on PHA-induced shoot growth was studied. Likewise, the effect of these inhibitors on the synthesis and activity of the phytoregulators concerned by PHA action in cucumber roots was also explored. The results show that shoot growth promoted by PHA is due to an increase of IAA concentration in the root through both a NO-dependent and a NO-independent pathway. In addition, the increased ethylene production in the root is regulated by an IAA-dependent pathway. Finally, results also showed that the increase of ABA concentration in the root is regulated through both IAA- and ethylene-dependent pathways. In summary, the shoot growth promoting action of PHA involves a complex hormonal network. On one hand, the PHA action is functionally linked to increments in NO and IAA concentration in roots. And on the other hand, PHA action also increases ethylene and ABA root concentration mediated by NO-IAA dependent pathways.