Phytohormone content in microstrobiles and androgenic callus of Siberian larch

Androgenesis in vitro in plants is a phenomenon of developmental switching of male generative cells, microspores, from their normal gametophytic to sporophytic pathway. We obtained androgenic callus and embryoids (embryo-like structures derived from microspores) of the conifer plant, Siberian larch (Larix sibirica Ledeb.) in the in vitro culture. The immune-enzyme analysis of the hormonal balance of larch androgenic cultures showed a substantial increase in the content of all phytohormones, especially cytokinins and ABA, as compared with initial explants (microstrobiles). This was evidently related to active cell divisions and embryoid formation. A comparison of androgenic cultures derived from trees nonifested and infested with larch gall midges (Dasineura rozhkovi Mam. et Nik.) revealed a cytokinin content increase (by two times) and an ABA content decrease (by two times), which indicates more intense growth of cultures derived from healthy trees. Phytohormone content in the androgenic callus was compared with their accumulation in the embryos of larch seeds harvested from noninfested trees. We concluded that successful growth of androgenic cultures and embryoid formation demand an additional medium supplement with auxins (not more than 0.5 mg/l).     

Callus cultures and bark from Norway spruce clones show similar cellular features and relative resistance to fungal pathogens

In field experiments, clones of Norway spruce [Picea abies (L.) Karst.] showed different degrees of resistance against pathogenic fungi inoculated into the bark that correlate with differences in polyphenolic parenchyma (PP) cells of the bark. Cells of spruce callus cultures, particularly towards the callus surface, resemble PP cells and this study looks at changes in callus cells during infection and the relative resistance of cultures from clones of low (weak) or high (strong) resistance to fungal infection. Callus cultures, initiated from trees with different resistance, were co-inoculated with Ceratocystis polonica (Siem.) C. Moreau and Heterobasidion annosum (Fr.) Bref. Callus cells from strong clones resemble PP cells of bark tissue from strong clones, having more polyphenolic bodies, while callus cells from weak clones are more similar to PP cells from those clones, which have less extensive phenolic bodies. Callus cultures from trees with weak resistance were more quickly overgrown by both species of pathogenic fungi than cultures from trees with strong resistance. Callus cells of infected cultures showed changes similar to activated PP cells of bark, including enhanced accumulation of polyphenolics. Phenolic bodies were more numerous and more extensive (larger and denser) in callus cells of strong versus weak clones under all conditions. Thus, callus cells may perform similar functions in defense as PP cells in the bark. Callus from trees of varying resistance seem to reflect the relative resistance of the trees from which they are derived, and this study indicates that some mechanisms of resistance can be studied using callus from trees of different resistance.     

Temperature conditions of the formation of frost damages in conifer trees in the high latitudes of Western Siberia

Frost damage to the bottom of the stem at a height of 0.2 m and at the height of the position of the thermometer in the weather station (2 m) and higher in the Siberian spruce (Picea obovata Ledeb.) and Siberian larch (Larix sibirica Ledeb.) growing at the northern limits of their natural habitat were studied in order to reveal the upper threshold temperature conditions of their formation. Possible causes of differences in the distribution of frost damage in the stem of the spruce and larch are discussed.     

Ophiostomatoid fungi associated withIps cembrae in Japan and their pathogenicity of Japanese larch

Six ophiostomatoid fungi, i.e.,Ceratocystiopsis minuta, Ceratocystis laricicola, Ophiostoma brunneo-ciliatum, O. laricis, O. piceae andOphiostoma sp., were isolated from the galleries ofIps cembrae on Japanese Iarch (Larix kaempferi) logs in central Honshu, Japan. Japanese larch trees approximately 30 yr old were inoculated with all six fungi.Ceratocystis laricicola produced the largest lesions on the inner bark around the inoculation point and the largest dry zone in the sapwood. Furthermore,C. laricicola was the only fungus associated withI. cembrae that had the ability to kill Japanese larch, death occurring in 30-yr-old trees within 3.5 mo after inoculation.     

Somaclonal variation of haploid in vitro tissue culture obtained from Siberian larch (Larix sibirica Ledeb.) megagametophytes for whole genome de novo sequencing

The objective of this study was to obtain a genetically stable haploid in vitro-derived line from Siberian larch (Larix sibirica Ledeb.) using megagametophyte explants, which then could be used for different molecular genetic studies, including whole genome de novo sequencing. However, cytogenetic analysis and genotyping of 11 microsatellite loci showed high levels of genomic instability and a high frequency of mutation in the obtained megagametophyte-derived callus cultures. All cultures contained new mutations in one or more microsatellite loci.     

The influence of the lower Ob River runoff on radial growth of trees

The influence of the Ob River runoff in its lower reaches on the radial growth of main forest-forming tree species-the Siberian spruce (Picea obovata Ledeb.), Siberian stone pine (Pinus sibirica Du Tour.), and larch (Larix sibirica Ledeb.)-was studied in the north of Western Siberia in various test sites both at the riverside and at a distance of 3 to 80 km from the Ob River floodplain. Differences in responses of the radial growth to air temperature in October and repeated frost damage of tree annual rings are observed in the Siberian spruce and Siberian stone pine depending on the distance from the river. The correlations of the radial growth of trees and frost damage with the effect of the Ob River runoff are discussed.     

Co-inoculation of Ceratocystis polonica and Heterobasidion annosum with callus of two Norway spruce clones with different in vivo susceptibility

We have studied how callus cultures from two clones of Norway spruce influence the growth of two pathogens, Ceratocystis polonica and Heterobasidion annosum, when co-cultivated in vitro. In field experiments, trees of clone 409 were susceptible to both fungi, whereas clone 589 was less affected. Callus was cultured on medium containing cytokinins (benzylaminopurine, kinetin) and with or without auxin (2,4-dichlorophenoxyacetic acid). For co-cultivation with fungus, one piece of callus was placed towards the edge of each Petri dish. One and 14 days after inoculation with callus the dishes were co-inoculated with the fungus. Both clones strongly stimulated the initial growth of both fungi. Clone 589 inhibited the growth of both fungi when the fungi were inoculated one day after the callus. When the callus was cultured on medium without auxin for 14 days before co-inoculation clone 589 strongly inhibited the growth of both fungi, whereas clone 409 inhibited H. annosum only. This revised version was published online in June 2006 with corrections to the Cover Date.     

Induction of conifer immune responses by phytopathogenic fungus metabolites

The elicitor activity of compounds extracted from the mycelia of six species of phytopathogenic fungi was assessed from the sizes of necrotic lesions on the external surface of the living trunk phloem of five coniferous species inhabiting Siberia: Siberian larch (Larix sibirica L.), Scotch pine (Pinus sylvestris L.), Siberian spruce (Picea obovata Ledeb.), Siberian fir (Abies sibirica L.), and cedar pine (Pinus sibirica (Rupr.) Mayr.). The compounds for inoculation were extracted from the mycelium of ascomycetes imperfect, and basidium fungi; the living mycelia of these fungi were also used. The fungal extract or mycelium was placed into the hollows 7 mm in diameter in the trunk bark. Infection triggered the formation of hypersensitivity necrotic lesions in the inner bark exceeding in size those appeared after control wounding of four tree species (larch, pine, spruce, and cedar); fir was an exclusion. In experiments with tree trunks and conifer calluses, a dependence of immune response parameters (the sizes of necrotic lesions and the content of lignin and bound proanthocyanidins) on the quantity of the fungal preparation was elucidated. The largest necrotic lesions appeared after injection of 500μg of the fungal preparation into the hollow in the trunk, and its higher quantities did not increase the indices measured. The size of the necrotic lesion on the trunk bark is supposed to be used as a promising index characterizing the level of tree immunity and tolerance under various ecological conditions.     

Study of the acid hydrolysis of polysaccharides from larch wood for obtaining crystalline glucose

This study has been conducted within the framework of the realization of complex wasteless technology for processing the biomass of the Siberian larch (Larix sibirica Ledeb.) and the Dahurian larch (L. gmelini (Rupr.) Rupr.). Experimental data on the acid hydrolysis of polysaccharides from the larch wood cellolignin residue have been summarized with the aim to develop the technology of manufacturing crystalline glucose.     

Defense response of pine stem phloem to wounding and treatment with mycelial extracts from <Emphasis Type="Italic">Ceratocystis laricicola</Emphasis>

Ophiostomatoid fungi colonize the conducting tissues of conifer stems, the phloem and the xylem. These pathogenic fungi penetrate into the stem through injuries made by xylophagous insects vectoring these pathogens. In this study the response of the phloem of Scotch pine (Pinus sylvestris L.) to wounding (treatment 1) was compared with the response to wounding combined with application of high-molecular-weight compounds isolated from the mycelium of the ophiostomatoid fungus Ceratocystis laricicola Redfern & Minter (treatment 2). Both treatments induced the appearance of necrosis in the inner bark, the formation of periderm separating living and dead tissues, and formation of the callus alongside the wound perimeter. In addition, the bark accumulated lignin, bound proanthocyanidins, and resins, with a parallel decrease in the content of free proanthocyanidins, low-molecular-weight carbohydrates, and non-lignin components of the cell wall (P > 0.95). The size of necrotic spots, as well as changes in the content of most substances, were significantly higher in the treatment 2 than in the treatment 1 (P > 0.95). The accumulation of lignin in cell walls of phloem sieve cells was delayed in the treatment 2 as compared with that in the treatment 1. This suggested that the mycelial extract temporarily inhibited lignification at the early stage of the wound response. This disturbance of the cell wall protective transformation led to the hypothesis that the fungal suppressors retard the repair of inner bark injured by insects, thereby favoring the invasion of conifer tissues by ophiostomatoid fungi.     

Temperature reconstruction in the Ob River valley based on ring widths of three coniferous tree species

Tree core samples of larch (Larix sibirica Ledeb.), spruce (Picea obovata Ledeb.) and pine (Pinus sibirica Du-Tour.) from the northern taiga of West Siberia were collected to assess their potential for summer temperature reconstructions in the Ob River region. Bootstrapped response functions showed that annual growth was mainly influenced by May to June temperatures in pine and by June to July temperatures in spruce and larch. Spruce and pine chronologies showed high positive correlations with previous October temperature. June–July temperatures were reconstructed based on spruce (1795–1996) and larch (1615–1999) tree ring chronologies. The pine chronology could not be used for a reliable temperature reconstruction, due to low values of explained May–June temperature variance (11–15%) but the species has a high potential to help clarify the May–June and October climatic influence on ring width observed in all three species. We explained the effect of the early vegetation period (May–July) and the differences in the temperature signals between spruce and larch tree ring chronologies with the influence of previous September and October temperature on tree growth with the warming effect of the Ob River and differences of the species’ photosynthetic possibilities and the activity of chloroplasts and bud meristem tissues.     

Influence of temperature on fractional composition of proteins and respiration of germinating seeds of Gmelin and Siberian larch

The influence of optimal and contrasting temperatures on the fractional composition of proteins and respiration of germinating seeds of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) and Siberian larch (Larix sibirica Ledeb.) was revealed. The dominance of globulins (salt-soluble fraction) and insoluble proteins was noted in viable air-dry seeds of larch. Optimal and contrasting temperatures of germination of seeds caused significant changes in the content and dynamics of separate fractions of protein, the contrasting temperatures causing greater changes: increasing in the content of insoluble proteins, intense consumption of globulins at separate stages of germination. Respiration of the seeds during germination at contrasting temperatures also increased more than at an optimal temperature. Thermal regime of germination affected the character of relations between the respiration rate and contents of different protein fractions.     

Polymorphism and structure of populations of Siberian spruce (<Emphasis Type="Italic">Picea obovata</Emphasis> Ledeb.) at the northern limits of the species distribution

Polymorphism of the main morphological characteristics of Siberian spruce (Picea obovata Ledeb.), which are used for diagnosing the species, as well as the population structure, was studied at the northern limits of the species habitat and compared with characteristics of spruce from the central regions of the area. The results obtained give an insight into the population structure of Siberian spruce and a pattern of its variation within the area.     

Phenolic compounds of Siberian and Dahurian larch phloem

The paper presents results of the investigation of phenolic compounds of the bark of the Siberian larch (Larix sibirica Ledeb.) and the Dahurian larch (Larix gmelini (Rupr.) Rupr). The flavonoids, stilbenes, phenolic acids have been identified on the basis of chemical, chromatographic and spectral data. Quercetin-3-O-??-L-rhamnopyranoside has been found for the first time in the bark of the Larix genus. Phenolic compounds with pyrocatechol type of substitution of aromatic ring have been found to dominate in the phloem of the larch species considered.     

Distribution of extractive substances in wood of the Siberian larch (Larix sibirica Ledeb.)

A distribution of extractive substances by height on the trunk and radius of the wood of the Siberian larch (Larix sibirica Ledeb.) was investigated. The maximum flavonoid content in terms of dihydroquercetin (the main flavonoid of the larch wood) was shown to be in the butt part of the tree. In the radial direction, this parameter increased from the center to periphery of the heartwood and reached the maximum value at the sapwood boundary. The maximum content of arabinogalactan (AG) was observed in the bottom and in the top of the trunk. The distribution of the extractive substances was studied in roots of the Siberian larch for the first time.     

Host responses in Norway spruce roots induced to the pathogen Ceratocystis polonica are evaded or suppressed by the ectomycorrhizal fungus Laccaria bicolor

The outcome of a compatible mycorrhizal interaction is different from that in a compatible plant–pathogen interaction; however, it is not clear what mechanisms are used to evade or suppress the host defence. The aim of this work is to reveal differences between the interaction of Norway spruce roots to the pathogen Ceratocystis polonica and the ectomycorrhizal Laccaria bicolor, examine if L. bicolor is able to evade inducing host defence responses typically induced by pathogens, and test if prior inoculation with the ectomycorrhizal fungus affects the outcome of a later challenge with the pathogen. The pathogen was able to invade the roots and caused extensive necrosis, leading to seedling death, with or without prior inoculation with L. bicolor. The ectomycorrhizal L. bicolor colonised primary roots of the Norway spruce seedlings by partly covering, displacing and convoluting the cells of the outer root cortex, leaving the seedlings healthy. We detected increased total peroxidase activity, and staining indicating increased lignification in roots as a response to C. polonica. In L. bicolor inoculated roots there was no increase in total peroxidase activity, but an additional highly acidic peroxidase isoform appeared that was not present in healthy roots, or in roots invaded by the pathogen. Increased protease activity was detected in roots colonised by C. polonica, but little protease activity was detected in L. bicolor inoculated roots. These results suggest that the pathogen efficiently invades the roots despite the induced host defence responses, while L. bicolor suppresses or evades inducing such host responses in this experimental system.     

Can Norway spruce trees be ‘vaccinated’ against attack by Ips typographus?

1 A field experiment was carried out to test the hypothesis that treatment of Norway spruce trees with the Ips typographus-transmitted blue-stain fungus Ceratocystis polonica enhances tree resistance to later mass attack by this bark beetle. 2 Twenty-five mature trees were pretreated by inoculating a non-lethal dose of the fungus into the bark, while 18 trees served as untreated controls. Three and a half weeks after treatment a bark beetle attack was initiated by attaching dispensers with I. typographus pheromone to the tree trunks. 3 A significantly larger proportion (67%) of the control trees than of the pretreated trees (36%) were killed by the beetle attack. The result is discussed in relation to recent results regarding defence mechanisms in Norway spruce trees.     

Seasonal variation in oxygen isotope composition of waters for a montane larch forest in Mongolia

Measurements of water oxygen isotopic composition were conducted in the 2003 growing season for a montane larch (Larix sibirica Ledeb.) forest in northern Mongolia, a transitional area from the south Siberian taiga to the Asian steppe. Oxygen isotopic composition of foliar water and its daily variability were found to be sensitive to atmospheric evaporative demand. During most of the growing season, water sources used by larch trees were from the upper 30-cm surface layer of the soil when precipitation input was large, and were from the deeper layer when the water supply at the upper soil layer was limited. The Keeling plot method suggested that the forest returned soil water to the atmosphere predominantly by means of canopy transpiration during the peak growth period (in August).     

Chromosomal mutations in Siberian larch (<Emphasis Type="Italic">Larix sibirica</Emphasis> Ledeb.) on Taimyr Peninsula

Chromosomal mutations were studied in the Norilsk population of Siberian larch (Larix sibirica Ledeb.) growing at the northeastern boundary of the species range affected by airborne smelter emissions. Different types of frequent chromosomal mutations have been revealed in the Norilsk population of L. sibirica and B-chromosomes have been found in this species for the first time.     

Antimicrobial and Antiradical Activities of Individual Fractions of Pinus sibirica Du Tour and Abies sibirica Ledeb. Growing in Siberia

Russian Journal of Bioorganic Chemistry - Essential oil from the spruce branches of Siberian pine (Pinus sibirica Du Tour) and Siberian fir (Abies sibirica Ledeb.) growing on the territory of...