Initiation of roots on hypocotyl cuttings of Pinus contorta in vitro

The origin of roots and wound tissue after treatments for induction of roots on hypocotyl cuttings of three-week-old Pinus contorta Dougl. ex Loud, is discussed. The cuttings were cultured in vitro and treated with 1.2 μ M to 1.5 M IBA (indole-3-butyric acid) for 6 h to 10 days. The control, which was not treated with IBA developed a wound tissue from which roots formed. Cuttings treated with IBA developed roots directly from the hypocotyl. Direct rooting was faster than indirect rooting via a wound tissue. Rooting was considered to be optimal if more than 80% of the cuttings rooted within 19 days and half of the cuttings which possessed roots after one month had acquired them within 14 days. This type of rooting was obtained after treatment with either 80 μ M IBA for 4 to 6 days or 1.25 to 5.0 m M IBA for 6 h. Suboptimal treatments gave lower rooting percentages and superoptimal treatments resulted in delayed rooting. In IBA-treated cuttings, large increases in mitotic activity (number of mitoses per mm hypocotyl) were found in the pericycle and parenchyma inside endodermis. However, the control also had similar mitotic activities as the IBA-treated cuttings but closer to the cut surface. This led us to the conclusion that similar tissues may produce either wound tissue or roots. Almost all roots obtained through direct rooting originated outside resin ducts.     

In vitro differentiation of plantlets from embryonic explants of lodgepole pine (Pinus contorta Dougl. ex Loud.)

A protocol is described for plantlet formation in juvenile tissues of Pinus contorta. Shoots were induced on embryonic, cotyledonary and hypocotyl explants cultured on a defined medium supplemented with cytokinin. The concentration of salts, vitamins and cytokinin (benzylamino purine) in the medium, as well as different temperature regimes, strongly influenced the frequency of bud formation. Differentiation of shoot primordia and their subsequent development was also markedly affected by cytokinin exposure times. Bud development and elongation were enhanced by elimination of the phytohormone, reducing the strength of mineral salts, vitamins and sucrose in the medium, as well as by the inclusion of charcoal. Rooting was induced by treating the shoots with a sterilized rooting powder containing indole-butyric acid and culturing them in agar-solidified medium containing reduced mineral salts, vitamins, sucrose and charcoal. The number of chromosomes and their structure were found to be normal in the regenerated plantlets.     

Adventitious root initiation in hypocotyl and epicotyl cuttings of eastern white pine (Pinus strobus) seedlings

The present paper reports results of experiments to develop a system for studying adventitious root initiation in cuttings derived from seedlings. Hypocotyl cuttings of 2-week-old eastern white pine (Pinus strobus L.) seedlings were treated for 5 min with 0, 100, 200, 300, 400, 500 or 600 mg l^?1 (0, 0.54, 1.07, 1.61, 2.15, 2.69 or 3.22 mM) 1-naphthaleneacetic acid (NAA) to determine the effect on root initiation. The number of root primordia per cutting was correlated with NAA concentration and the square of NAA concentration. Thus, the number increased from less than one per cutting in the 0 NAA treatment to approximately 40 per cutting at 300 mg l-1 NAA, above which no substantial further increase was observed. The larger number of root primordia formed in response to increasing concentrations of NAA was due to the formation of primordia over a larger proportion of the hypocotyls. Histological analysis of the timing of root primordium formation in hypocotyl cuttings revealed three discernible stages. Progression through these stages was relatively synchronous among NAA-treated hypocotyl cuttings and within a given cutting, but variation was observed in the portion of different cuttings undergoing root formation. Control-treated hypocotyl cuttings formed root primordia at lower frequencies and more slowly than NAA-treated cuttings, with fewer primordia per cutting. Epicotyl cuttings from 11-week-old seedlings also formed adventitious roots, but more slowly than hypocotyl cuttings. NAA treatment of epicotyl cuttings caused more rapid root initiation and also affected the origin of adventitious roots in comparison with nontreated cuttings. NAA-treated epicotyl cuttings formed roots in a manner analogous to that of the hypocotyl cuttings, directly from preformed vascular tissue, while control-treated epicotyl cuttings first formed a wound or callus tissue and subsequently differentiated root primordia within that tissue. This system of inducing adventitious roots in pine stem cuttings lends itself to studying the molecular and biochemical steps that occur during root initiation and development.     

Multilocus structure in Pinus contorta Dougl.

We studied isozyme variation at 21 loci in 66 populations from three subspecies of Pinus contorta Dougl.; 35 in spp. latifolia, 20 in spp contorta and 11 in spp. murrayana. The objectives were to assess gametic disequilibria and multilocus structure. There was considerable differentiation of allele frequencies at 19 polymorphic loci across the 66 populations and within the subspecies. Allele frequencies at many loci correlated with geographic variables. Genetic variability varied considerably among populations within subspecies but the subspecies means were similar. The mean number of polymorphic loci and the mean heterozygosity over 19 polymorphic loci were, respectively, 13 and 0.194 in latifolia, 12 and 0.196 in murrayana, and 12 and 0.180 in contorta. The mean heterozygosity correlated with longitude and altitude across the 66 populations and with latitude in latifolia. Gametic disequilibria were evident in 40 populations; 29 in latifolia, eight in murrayana and three in contorta. Gametic disequilibria correlated with latitude across the 66 populations and with longitude in latifolia. The single-locus F _ST averaged 0.0339 in latifolia, 0.0567 in murrayana, and 0.0764 in contorta. The multilocus F _STM was 0.1227 in latifolia, 0.2926 in murrayana, and 0.3328 in contorta. Multilocus Wahlund and founder effects, migration patterns, and natural selection, probably played significant roles in generating and maintaining the multilocus genetic structure in P. contorta in general and the subspecies latifolia in particular.     

Effects of Auxins and other Factors on the Rooting of Pinus contorta Dougl. Cuttings

The effects are investigated of applications of NAA and IBAupon root number, root type and time to form first roots incuttings of Pinus contorta Dougl. Cuttings treated with NAAgenerally formed thick, fleshy, unbranched roots, while thosereceiving IBA produced a thin, finely-divided root system. Bothtypes of roots developed when the two hormones were appliedtogether. The time taken for first roots to form, and the finalnumber of rooted cuttings were also greatly increased when hormoneswere applied in the range 1–10 µg per cutting. Boricacid applied in combination with hormone treatments increasedrooting, but boron alone was ineffective. There were markeddifferences between clones in their rooting responses to bothhormone and boron treatments.     

Genic diversity, genetic structure, and biogeography of Pinus sabiniana Dougl.

Pinus sabiniana Dougl. (grey pine) forms savanna forests in the foothills surrounding California's Great Central Valley. However, its fossil record, which dates from the late Miocene through the Pliocene and Pleistocene, is found exclusively in southern California, south of the species’ present range. A total of twenty-nine isozyme loci, representing eighteen enzyme systems, was assayed to analyse the genetic structure in eight populations of grey pine and attempt to track its migration history from southern to northern California. Expected heterozygosity in the two southernmost samples was 0.128 and 0.150, and heterozygosity tended to decrease with increasing latitude, suggesting the loss of diversity as grey pine dispersed northward. However, genetic distances between populations were very small, even on opposite sides of the treeless Great Central Valley; and estimated time since divergence was 900 to 9000 years at a maximum. Wright's F_ST, the proportion of total genetic diversity among populations, was only 0.057, which is similar to values found in many conifers with continuous distributions. Nm, the number of migrants among populations per generation, was 4.1 to 6.7, depending on estimator, and indicates that gene flow is extensive, or was so in the recent past. In every population, observed heterozygosity was less than expected heterozygosity, and the fixation index, F_IS, for the progeny was 0.128, which indicates a fairly high rate of inbreeding. The genetic similarity of disjunct populations, in combination with paleogeographic and paleoclimatic evidence, suggests that grey pine formed a continuous population throughout the Great Central Valley, perhaps between 12,000 and 8000 yrs BP . Its range became fragmented during the Xerothermic, when it ascended into the foothills. Gaps in its range correlate with late Pleistocene–early Holocene lakes in adjacent basins and with the Sacramento–San Joaquin Delta.     

NAA处理桉树插条后IAAO活性与生根的关系

尾叶桉MLA无性系(简称MLA)为难生根植物,尾叶桉U₆无性系(简称U₆)和刚果12号桉W₅无性系(简称W₅)为相对易生根植物。MLA插条内的吲哚乙酸氧化酶(IAAO)活性较U₆、W₅的高。用萘乙酸(NAA)处理桉树插条后,在扦插生根的不同阶段,插条内IAAO活性呈现规律性变化;可溶性蛋白质含量呈上升趋势。本文讨论了IAAO与桉树插条生根的关系。     

Initiation and development of wound tissue and roots on hypocotyl cuttings of Pinus sylvestris in vitro

The rooting of hypocotyl cuttings from 20-day-old seedlings of Pinus sylvestris L. cultured in vitro is discussed. About 40% of the cuttings cultured on medium lacking activated charcoal produced roots during the first two months. When activated charcoal was added to the medium, either root formation (75% formed roots) or wound tissue growth (95% formed large wound tissues) was stimulated in different experiments. These large wound tissues did not develop any roots. The anatomical changes in the basal part of the cuttings were similar during the first two weeks in all the cuttings studied. A vascular cylinder composed of short tracheids with many pores developed. Thereafter the differentiation process became varied. The amount of wound tissue produced and the time for rooting differed among the cuttings. Tracheid nests which were in contact with the vascular system in the hypocotyl via short tracheids were observed after three weeks. Subsequently, roots developed from the tracheid nests. The longer root formation was delayed, the larger the wound tissue became.
Short tracheids were found close to the wound tissue surface. Their ability to adsorb nutrients and water is discussed.     

Rooting and acclimatization of micropropagated cuttings of Pinus pinaster and Pinus sylvestris are enhanced by the ectomycorrhizal fungus Hebeloma cylindrosporum

The effect of different strains of the ectomycorrhizal fungus Hebeloma cylindrosporum on rooting in vitro and acclimatization of micropropagated cuttings of Pinus pinaster and Pinus sylvestris was studied. Two clones of P. pinaster and one of P. sylvestris were unable to root in the absence of auxin, but were induced to root on a medium devoid of auxin by all the fungal strains. Wild-type and indoleacetic acid (IAA)-overproducing mutant strains of the fungus stimulated rooting of clones showing a good reactivity to auxin to the same extent. In contrast, with a clone of P. sylvestris that showed low reactivity to auxin, IAA-overproduction by the fungus was advantageous for the induction of rooting of cuttings. Adventitious roots formed in the presence of a fungal strain were completely surrounded by a loosely packed network of hyphae which formed mycorrhizas as soon as roots grew outside the agar medium. During acclimatization, fungal inoculation improved the survival of rooted cuttings. At the end of acclimatization, fungal mycelia could be easily detected in the culture substrate of cuttings inoculated with dikaryotic strains and most of the pines' short roots were mycorrhizal. Monokaryotic mycelia, which have a lower growth rate and a lower infectivity, displayed poor ability to colonize the substrate and to form mycorrhizas. Two months after the end of acclimatization, fungal inoculation frequently depressed the growth of acclimatized cuttings of the clone J of P. pinaster . No depressive effect was observed with clone 78 and growth stimulation could even be observed with the infective dikaryon D1 which formed numerous mycorrhizas. From these studies, it was concluded that ectomycorrhizal fungi could be a suitable tool for improving rooting in vitro and survival at acclimatization of micropropagated conifer cuttings.     

A Comparison of the Rates of Growth and Photosynthesis in First-Year Seedlings of Four Provenances of Pinus contorta Dougl

The results of four experiments are reported in which the parametersof growth were examined in first-year seedlings of Pinus contortaDougl. raised from seed of four different geographic origins(provenances). Highly significant differences in net photosynthesis were shownbetween provenances over a wide range of light intensities,in plants of both 12 and 19 weeks of age, when measurement wasmade at a temperature of 20 ?C. Provenances with a high netrate of photosynthesis also had a high rate of dark respiration,consequently provenance differences in gross photosyntheticrate paralleled those in net photosynthetic rate. Leaf-weightratios (i.e. the ratios of leaf weight: plant weight) also differedsignificantly between provenances, and there was an over-allnegative correlation between rates of photosynthesis and leaf-weightratios. Differences in relative growth-rate (RGR) result fromdifferences in the component variables, photosynthetic rate,and leaf-weight ratio. As the values of these two parameterswere negatively correlated in the experiment, the RGRs of thefour provenances differed little during the mid-seasonal periodof growth. It was not possible, despite precise measurementsof dry-weight increment made on plants grown in nutrient solution,to show inter-provenance differences in RGR which were statisticallysignificant during the mid-seasonal period. Marked inter-provenance differences occurred in the length ofgrowing season, as measured by the time interval between germinationand terminal bud formation, and these differences were associatedwith differences in seedling height. They were not, at leastwithin the time period examined, associated with differencesin seedling weight, and the significance of this fact is discussedin terms of productivity studies for forest tree species.     

Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents,Pinus tabuliformis and Pinus yunnanensis

Genetic analyses indicate that Pinus densata is a natural homoploid hybrid originating from Pinus tabuliformis and Pinus yunnanensis. Needle morphological and anatomical features show relative species stability and can be used to identify coniferous species. Comparative analyses of these needle characteristics and phenotypic differences between the artificial hybrids, P. densata, and parental species can be used to determine the genetic and phenotypic evolutionary consequences of natural hybridization. Twelve artificial hybrid families, the two parental species, and P. densata were seeded in a high‐altitude habitat in Linzhi, Tibet. The needles of artificial hybrids and the three pine species were collected, and 24 needle morphological and anatomical traits were analyzed. Based on these results, variations in 10 needle traits among artificial hybrid families and 22 traits among species and artificial hybrids were predicted and found to be under moderate genetic control. Nineteen needle traits in artificial hybrids were similar to those in P. densata and between the two parental species, P. tabuliformis and P. yunnanensis. The ratio of plants with three needle clusters in artificial hybrids was 22.92%, which was very similar to P. densata. The eight needle traits (needle length, the mean number of stomata in sections 2 mm in length of the convex and flat sides of the needle, mean stomatal density, mesophyll/vascular bundle area ratio, mesophyll/resin canal area ratio, mesophyll/(resin canals and vascular bundles) area ratio, vascular bundle/resin canal area ratio) relative to physiological adaptability were similar to the artificial hybrids and P. densata. The similar needle features between the artificial hybrids and P. densata could be used to verify the homoploid hybrid origin of P. densata and helps to better understand of the hybridization roles in adaptation and speciation in plants.     

Ethanol synthesis, nitrogen, carbohydrates, and growth in tissues from nitrogen fertilized Pseudotsuga menziesii (Mirb.) Franco and Pinus ponderosa Dougl. ex Laws. seedlings

 Seedlings of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and ponderosa pine, Pinus ponderosa Dougl. ex Laws., were grown in a controlled environment and fertilized with nutrient solutions containing 150 ppm (+N), or 0 ppm nitrogen (−N). These treatments greatly altered seedling growth, and the concentrations of N and carbohydrates in their tissues. Metabolically active tissues, such as roots, incubated with a limited supply of O₂ became hypoxic faster and synthesized more ethanol than less active tissues, such as needles. All tissues that were incubated for 4 h in N₂ synthesized ethanol. Needles incubated in N₂ and light had much lower quantities of ethanol than needles in N₂ and dark, suggesting that O₂ from photosynthetsis limited internal anoxia. Most tissues from +N seedlings synthesized greater quantities of ethanol in N₂ anoxia than tissues from −N seedlings, probably because they were able to produce more enzymes with a greater availability of N. However, this increase in ethanol synthesis between N treatments was most pronounced in the phloem. Ethanol and soluble sugar concentrations were negatively related in needles and positively related in roots of N+ seedlings, but not −N seedlings. Starch concentrations had no effect on the amount of ethanol produced by any tissue. Regardless of N treatments, all tissues from ponderosa pine produced more N₂-induced ethanol than Douglas-fir, in part because its tissues contained different concentrations of soluble sugars and N as a consequence of phenological differences between the species. However, ponderosa pine tissues may also maintain greater quantities of anaerobic enzymes, or their isozymes than Douglas-fir. Received: 22 February 1998 / Accepted 23 June 1998     

Metabolic changes during rooting in stem cuttings of Casuarina equisetifolia L.: effects of auxin, the sex and the type of cutting on rooting

Rooting in terminal shoot and lateral shoot cuttings from 10-year-old elite trees of Casuarina equisetifolia L. in different sex groups was achieved after 20 days when the basal ends of the cuttings were dipped for 3 h in 20 ppm indole-3-butyric acid (IBA). Shoots derived from male plants rooted better than their female and monoecious counterparts, and the lateral shoots were more responsive to rooting than the terminal shoots. During rooting, the metabolic activities varied in both lateral shoot and terminal shoot cuttings derived from plants under different sex groups. Peroxidase and polyphenoloxidase activities were high during root initiation and showed a sharp decline thereafter. The polyphenoloxidase activity was higher in the lateral shoot than the terminal shoot cuttings. The rooted plantlets survived and established well in the field.Abbreviations IAA indole-3-acetic acid - IBA indole-3-butyric acid - NAA 1-naphthaleneacetic acid - PVP polyvinylpyrrolidone     

甘蔗废糖蜜对绿豆插条下胚轴生根的影响

本文研究甘蔗废糖蜜对绿豆插条下胚轴生根的影响,结果表明,1000~7000mg/L浓度范围内的甘蔗废糖蜜能明显增加绿豆插条下胚轴不定根的数目、根长、根干重及生根范围,并促进不定根内可溶性糖含量和不定根系活力提高。     

Effects of auxin and irradiance on the rooting of cuttings of Pinus sylvestris

Abstract Seedlings of Pinus sylvestris L. were grown under controlled conditions (temperature 20°C, photoperiod 17 h) at two irradiances, 8 or 40 W m^-2. Hypocotyl cuttings were excised and rooted at different irradiances in tap water solutions of indolebutyric acid (IBA). The fastest rooting and highest rooting percentage were obtained with cuttings from stock plants grown at 8 W m^-2 and treated with 10^-5M IBA for 21 days. The concentration of 10^-4M IBA inhibited root formation. In comparable treatments rooting was always better in cuttings from stock plants grown at 8 W m^-2 than in cuttings from stock plants grown at 40 W m^-2. The irradiance during the rooting period had only a minor influence on rooting. When cuttings from plants irradiated with 40 W m^-2 were treated with 10^-5M IBA for 21 days the rooting percentage almost reached the same level as in untreated cuttings from stock plants given 8 W m^-2. In cuttings treated with IBA during the whole rooting period, rooting was depressed in comparison to untreated cuttings. Aeration of the 10^-4M IBA solution increased the rooting percentage, but aeration had no effect on untreated cuttings and on cuttings treated with lower IBA concentrations.     

The effect of indole-3-acetylaspartic acid on adventitious root formation on bean cuttings

The influence of indole-3-acetylaspartic acid (IAAsp) on rooting of stem cuttings from bean plants (Phaseolus vulgaris L.) of different ages, cultivated at different temperatures (17°, 21° and 25°C) was studied and compared to that of indole-3-acetic acid (IAA). At a concentration of 10^–4 M, IAAsp only nonsignificantly stimulated adventitious root formation, approximately to the same level as IAA in all treatments. IAAsp at 5×10^–4 M further enhanced rooting, by up 200% of control values, with little influence of temperature conditions and stock plant age. This concentration of IAA usually stimulated rooting more than the conjugate. The largest differences between the effects of IAAsp and IAA occured at the highest cultivation temperature of 25°C where stock plant age also influenced the response. The number of roots produced in comparison with the control, was enhanced from 350% on cuttings from the youngest plants to more than 600% on cuttings from the oldest. In contrast to the conjugate, 5×10^–4 M IAA induced hypocotyl swelling and injury of the epidermis at the base of cuttings, in all treatments.     

Changes in peroxidase isoenzymes of Phaseolus mungo hypocotyl cuttings during rooting

A time course study of changes in the pattern of peroxidase isoenzymes shows that two new isoenzymes a and b appeared in hypocotyl cuttings in     

Etiolation of stock plants affects adventitious root formation and hormone content of pea stem cuttings

Stock pea plants (Pisum sativum L.) were etiolated fully or partially at the third internode that acted as the cutting base. The etiolation started the fifth day after sowing and lasted till cutting preparation. Cuttings derived from partially etiolated plants rooted more than non-etiolated ones while fully etiolated ones rooted more only after treatment with 1% sucrose solution for 4 days. Endogenous IAA in the base of etiolated cuttings was higher during the first 24 h after cutting preparation than in the control. Z/ZR did not show significant differences while iAde/iAdo was higher in the control. Ethylene was increased 24 h after cutting preparation and the increase was greater from partially etiolated cuttings. The results showed that besides IAA and cytokinins, which played a role in the rooting of cuttings, sucrose influenced rooting in the case of fully etiolated stock plants.