Morpho-anatomical and biochemical changes associated with rooting of micropropagated ninebark cuttings

Ninebark (Physocarpus opulifolius) is an attractive ornamental shrub with poor rooting characteristics in some cultivars, which is a limiting factor in commercial production This study was designed to optimize rooting conditions of ninebark cuttings and to observe the effect of exogenous auxin IBA on some morpho-anatomical and biochemical changes associated with rhizogenesis in the in vitro conditions. Both auxins under study: the indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) gave comparable effects but the combination of ½ MS?+?1 mg·L^?1 IBA was the most cost effective for all rooting parameters. Anatomical changes at the cuttings’ bases during root formation were typical for woody plants and they were accelerated by auxin in the culture medium. High levels of the endogenous indole acid and hydrogen peroxide were temporarily associated with intensive cell divisions in cuttings, and the polyphenolic acid contents kept increasing during rooting above the initial levels and those in controls.

     

Involvement of the Cotyledon in Adventitious Root Initiation in Impatiens balsamina L. Seedlings

Adventitious root primordia are found in the pre-hypocotyl tissueof developing seeds of Impatiens balsamina L. by the third weekafter petal drop, and are present in the mature seed. Aftergermination, the adventitious roots emerge from a collet swellingon the hypocotyl of the young seedlings. Removal of the colletduring the first five days results in the formation of anotherat the base of the remaining hypocotyl. Older seedlings respondto the excision of the collet by producing one or more rootsnear the cut end, unless the cut is made close to the cotyledon,when, even in nine-day seedlings, a reduced collet is formedassociated with four or fewer roots. The influence of the cotyledonon collet/root regeneration diminishes in older seedlings andin these is manifested only in hypocotyl tissue adjacent tothat organ. Impatiens balsamina, balsam, cotyledon, adventitious roots, collet     

Root Growth, Secondary Root Formation and Root Gravitropism in Carotenoid-deficient Seedlings of Zea mays L.

The effect of ABA on root growth, secondary-root formation androot gravitropism in seedlings of Zea mays was investigatedby using Fluridone-treated seedlings and a viviparous mutant,both of which lack carotenoids and ABA. Primary roots of seedlingsgrown in the presence of Fluridone grew significantly slowerthan those of control (i.e. untreated) roots. Elongation ofFluridone-treated roots was inhibited significantly by the exogenousapplication of 1 mM ABA. Exogenous application of 1 µMand 1 nM ABA had either no effect or only a slight stimulatoryeffect on root elongation, depending on the method of application.The absence of ABA in Fluridone-treated plants was not an importantfactor in secondary-root formation in seedlings less than 9–10d old. However, ABA may suppress secondary-root formation inolder seedlings, since 11-d-old control seedlings had significantlyfewer secondary roots than Fluridone-treated seedlings. Rootsof Fluridone-treated and control seedlings were graviresponsive.Similar data were obtained for vp-9 mutants of Z. mays, whichare phenotypically identical to Fluridone-treated seedlings.These results indicate that ABA is necessary for neither secondary-rootformation nor for positive gravitropism by primary roots. Zea mays, gravitropism, carotenoid-deficient, Fluridone, root growth, vp-9 mutant     

Greenhouse propagation of Cannabis Sativa L. by vegetative cuttings

Previous work revealed significant variations in cannabinoid profiles ofCannabis sativa L. derived from a single seed source (P.1. 378939) and subjected to the same growth environment. Studies were conducted to evaluate the efficacy of propagation ofC. sativa by vegetative cuttings in order to increase uniformity of cannabinoid concentrations within a given plant population.C. sativa was successfully propagated by vegetative cuttings. However, there were both morphological and biochemical differences between seed-derived plants and their vegetative propagules. Delta-⁹-tetrahydrocannabinol concentrations were 4.1 times higher in vegetative propagules than in seed propagules. Vegetative cuttings also generally developed more profuse lateral branch growth; hence, foliage increased relative to their parent plants. Cannabinoid levels within the population of vegetative cuttings remained highly variable.     

Root initiation in Vigna radiata (L.) Wilczek hypocotyl cuttings is stimulated by smoke-derived extracts

Aqueous extracts of smoke, derived from Themeda triandra, a fire-climax grass, and Passerina vulgaris, a fynbos plant, stimulated root initiation and development in the hypocotyls of mung beans. Immersion time and the dilution of the smoke extracts were important in optimising the rooting response.     

Photoperiodic studies on growth and development of Impatiens balsamina L.

Summary Seedlings of Impatiens balsamina raised under ND and LD conditions were divided into two sub-groups each when they had reached 5-leaf stage. While one sub-group was left under the same condition (NDND or LDLD), the other was transferred to the other photoperiod (NDLD or LDND). NDND plants were subdivided into 2 lots. One of these was transferred to SD in May. The dates of emergence of individual branches and floral buds were recorded and the vegetative period was calculated in each case.It was found that in NDND plants floral buds were produced from all the nodes except the lowermost which produced a single vegetative branch. In LDND plants the vegetative branches were produced from the lower 9 nodes but floral buds from those above these. Small leafy structures which ultimately dried up were produced from a few top nodes in both these cases. In contrast to this in LDLD plants only vegetative branches were produced from all the nodes. In NDLD plants floral buds were produced from the lower 3–5 nodes prior to transfer to LD condition, but vegetative branches were produced from the upper nodes after this transfer. Even some of the lower floral buds reverted to vegetative state under this condition.The production of floral buds or the vegetative branches as the case may be, occurred in acropetal succession under all the photoperiodic conditions and never in basipetal manner.LDLD and NDLD plants, which did not flower at all, continued to produce lateral branches without showing any sign of senescence, while LDND and NDND ones showed yellowing of the apical growing point which spread downwards and lead ultimately to the death of the plant. The senescence was hastened when these plants were transferred to SD condition towards the end of May. The senescence therefore, appears to be related with reproductive development. The results are discussed in the light of current literature.     

Photoperiodic studies on growth and development of Impatiens balsamina L.

Summary In the short-day plant Impatiens balsamina it was found that, while floral buds are initiated with 3 short-day (SD) cycles, at least 8 such cycles are required for flowering. The numbers of floral buds and open flowers bear a linear relationship with the number of SD cycles. The induced floral buds revert to vegetative growth unless the plants receive the minimum number of SD cycles needed for flowering, this reversion occurring in a basipetal direction. The rate of extension growth of the stem increases with increasing numbers of SD cycles. The high rate is maintained longer in plants receiving 32 or more SD cycles, but the subsequent fall is also steeper in these plants than in plants receiving less inductive cycles. Senescence also occurs in these plants and appears to be related to the magnitude of reproductive development and the high rate of extension growth.     

Stimulation of Root Elongation and Curvature by Calcium

Ca²⁺ has been proposed to mediate inhibition of root elongation. However, exogenous Ca²⁺ at 10 or 20 millimolar, applied directly to the root cap, significantly stimulated root elongation in pea (Pisum sativum L.) and corn (Zea mays L.) seedlings. Furthermore, Ca²⁺ at 1 to 20 millimolar, applied unilaterally to the caps of Alaska pea roots, caused root curvature away from the Ca²⁺ source, which was caused by an acceleration of elongation growth on the convex side (Ca²⁺ side) of the roots. Roots of an agravitropic pea mutant, ageotropum, responded to a greater extent. Roots of Merit and Silver Queen corn also responded to Ca²⁺ in similar ways but required a higher Ca²⁺ concentration than that of pea roots. Roots of all other cultivars tested (additional four cultivars of pea and one of corn) curved away from the unilateral Ca²⁺ source as well. The Ca²⁺-stimulated curvature was substantially enhanced by light. A Ca²⁺ ionophore, A23187, at 20 micromolar or abscisic acid at 0.1 to 100 micromolar partially substituted for the light effect and enhanced the Ca²⁺-stimulated curvature in the dark. Unilateral application of Ca²⁺ to the elongation zone of intact roots or to the cut end of detipped roots caused either no curvature or very slight curvature toward the Ca²⁺. Thus, Ca²⁺ action on root elongation differs depending on its site of application. The stimulatory action of Ca²⁺ may involve an elevation of cytoplasmic Ca²⁺ in root cap cells and may participate in root tropisms.     

ABA associated biochemical changes during somatic embryo development in Camellia sinensis (L.) O. Kuntze

The effect of ABA on reserve accumulation in maturing somatic embryos of tea was compared with and without ABA treatment. Changes in the levels of starch, total soluble sugars (TSS), proteins, and phenols were studied in the somatic embryos at different stages of development (globular, heart, torpedo and germinating embryos) in order to investigate whether ABA could trigger accumulation of storage reserves and thereby overcome the problem of poor germination. After ABA treatment (5.0 mg l(-1)) for 14 days, the starch and protein contents that were negligible in the untreated embryos increased by several fold with a simultaneous increase in TSS. When ABA treatment occurred at the heart stage, the germination of the embryos also improved, relative to untreated controls, after ABA treatment. ABA treatment prior to or after heart stage did not improve somatic embryo germination.     

Effect of morphactin on peroxidases and its relationship to rooting hypocotyl cuttings of Impatiens balsamina

Morphactin inhibited the production of roots on hypocotyl cuttingsof Impatiens balsamina with intact apex and cotyledons. Rootswere, however, initiated when cuttings were transferred to water.A new peroxidase isoenzyme in the cotyledons and two in thehypocotyls that were absent in controls, appeared in morphactin-treatedcuttings. However, one isoenzyme in the cotyledons and threein the hypocotyls that were absent in morphactin-treated cuttings,were detected in the controls. These isoenzymes may be involvedin the initiation and development of roots. (Received August 15, 1972; )     

Stimulation of adventitious root formation in non-woody stem cuttings by uridine

Uridine strongly stimulated adventitious root formation in stem cuttings of sunflower (Helianthus annuus L.), mung bean (Vigna radiata L.) and common bean (Phaseolus vulgaris L.). A dose response curve of uridine induced rooting showed that the optimum concentration of uridine was 0.1 µM. At all concentrations employed, uridine had no significant effect on root elongation. The rooting response of stem cuttings to the optimal concentration of indole-3-butyric acid (10 µM) in combination with 0.1 µM uridine did not significantly differ from their response to either of these compounds when applied alone. However, the rooting response of the cuttings to sub-optimal IBA (0.01 µM) was significantly stimulated by uridine. These findings suggested that uridine may have stimulated rooting by increasing the sensitivity of the rooting tissue to auxin.     

The Effect of Acute Irradiation of Balsam Seeds(Impatiens balsamina L. ) on the Formation of Anthocyanins in Blossoms

V uvedené práci jsem sledovala nep?ímý vliv zá?ení na produkci antokyan? v květech ?ervené balsaminyImpatiens balsamina L. Po 18 hodinách bub?ení byla semena ozá?ena dávkou 4560 r a sledovány změny v antokyanisaci květ?. V X₀ do?lo u t?ech ze ?ty? sledovaných linií pr?kaznému zvý?ení obsahu antokyan?. 18 %, 18 % a 29 %. V X₁ se kvantitativni obsah antokyan? bud vyrovnal s kontrolami nebo byl ni??í, v X₂ do?lo pr?kaznému snízení obsahu antokyan? u v?ech sledovaných linii oproti kontrolám. Z?ejmě se jedná o fysiologické ovlivnění typu ?dlouhodobych vyznívajících modifikací“. V X₁ se objevilo několik r?zovych rostlin (3,4 %). Domnívám se, ?e nejde o vy?těpení následkem heterozygotního materiálu (u kontrol se nic takového neobjevilo), ?e v?ak vlivem zá?ení do?lo recesivní mutaci, která se projevila a? v X₁.     

Physiological and biochemical changes associated with cotton fiber development. VIII. Wall components

Fibers of three cotton cultivars (Gossypium hirsutum L.) H-4, H-8 and (G. arboreum) G. Cot-15, which shows variation in staple length were analyzed for growth in terms of fiber length and fresh and dry mass. From the growth analysis cotton fiber development is divided in four distinct phases i.e. (i) initiation (ii) elongation (iii) secondary thickening and (iv) maturation. Rate of fiber elongation and rate of water content shows close parallelism. Highly esterified and less esterified pectic fraction along with high and low molecular weight xyloglucan fractions were estimated from fiber walls of all the three cotton genotypes. Xyloglucans were fractioned in to high and low molecular weight by alkali treatment, 1 M and 4 M KOH respectively. Xyloglucan content shows inverse correlation with fiber elongation. Role of water content and wall components in determination of staple length in cotton genotypes is discussed.     

Physiological and biochemical changes associated with cotton fibre development

Growth kinetics and levels of auxin substances were studied in three cotton cultivars, designated as long, medium and short staple cultivars. Fibre length and dry weight plotted against boll age showed sigmoidal patterns and were fitted to a logistic curve by computer curvilinear regression analysis. The final length of the fibre in different cultivars was the product of the rate of elongation per day and the total period of elongation. Further, considerable overlap between the elongation and the secondary thickening phases was recorded.
No relationship between auxin substances and rate of fibre elongation was discernible. The peak levels of auxin substances in all the cultivars were recorded before or about the time when elongation had just started, and it is concluded that the auxin synthesized during the elongation phase is consumed in elongation growth. Thus there is necessarily no relationship between remaining auxin and growth.     

Physiological and biochemical changes associated with cotton fibre development

The relationship between growth and some enzymes of carbohydrate metabolism in developing cotton fibre were studied. Two respiratory pathways of glucose oxidation i.e. oxidative pentose phosphate pathway (OPPP) and glycolysis operates in the elongating cotton fibres and the extent of their operation varies with the demand for respiratory products. In this respect, hexokinase, G-6-PDH, 6PGDH, and MDH show increased activities during the period of rapid cell elongation and decreased activities when rate slows down. The conversion of PEP to malate and/or via a transhydrogenase system consisting of enzymes PEPC, MDH and NADP-MDH(d) may play a significant role in carbohydrate compartmentation of developing cotton fibre. As the rate of fibre growth slows down, a decline in enzyme activities, points to a shift in metabolic priorities.