(1/76) Detection of intracellular bacteria in the buds of Scotch pine (Pinus sylvestris L.) by in situ hybridization.

Bacterial isolates were obtained from pine (Pinus sylvestris L.) tissue cultures and identified as Methylobacterium extorquens and Pseudomonas synxantha. The existence of bacteria in pine buds was investigated by 16S rRNA in situ hybridization. Bacteria inhabited the buds of every tree examined, primarily colonizing the cells of scale primordia and resin ducts.  (+info)

(2/76) The electrical impedance spectroscopy of Scots pine (Pinus sylvestris L.) shoots in relation to cold acclimation.

Electrical impedance spectroscopy (EIS) was applied to stems of Scots pine (Pinus sylvestris L.) in a provenance field trial during frost hardening to find an EIS parameter for assessing frost hardiness (FH) without a controlled freezing test. The FH of stems and needles assessed by controlled freezing tests was compared with the equivalent circuit EIS parameters of a distributed model of stems (not exposed to controlled freezing treatment) and with dry matter (DM) content of stems. Significant differences in the equivalent circuit parameters, FH and DM content were found between provenances. The relaxation time (tau(1)), describing the peak of the high frequency arc of the impedance spectrum, and the intracellular resistance (r(i)) of stems increased with increasing FH. According to the linear regression, the coefficient of determination (R(2)) between the FH of stems and needles with tau(1) of the stem was 0.87 and 0.89, and with r(i) of the stem 0.74 and 0.85, respectively. The relation between FH and tau(1) changed with the degree of hardiness. The highest coefficient of determination was 0.95 in September when the FH of needles, ranging from -10 degrees C to -25 degrees C, was predicted with an accuracy of +/-2.0 degrees C. The resistance parameter r(2), describing the width of the low frequency arc of the impedance spectrum, decreased prior to and during the initial hardening: significant differences were found between provenances. This indicates that r(2) was not related to frost hardening per se. It is concluded that it is possible to distinguish the hardening patterns of different provenances by tau(1) in the rapid phase of hardening without controlled freezing tests.  (+info)

(3/76) Developmental regulation of indole-3-acetic acid turnover in Scots pine seedlings.

Indole-3-acetic acid (IAA) homeostasis was investigated during seed germination and early seedling growth in Scots pine (Pinus sylvestris). IAA-ester conjugates were initially hydrolyzed in the seed to yield a peak of free IAA prior to initiation of root elongation. Developmental regulation of IAA synthesis was observed, with tryptophan-dependent synthesis being initiated around 4 d and tryptophan-independent synthesis occurring around 7 d after imbibition. Induction of catabolism to yield 2-oxindole-3-acetic acid and irreversible conjugation to indole-3-acetyl-N-aspartic acid was noticed at the same time as de novo synthesis was first detected. As a part of the homeostatic regulation IAA was further metabolized to two new conjugates: glucopyranosyl-1-N-indole-3-acetyl-N-aspartic acid and glucopyranosyl-1-N-indole-3-acetic acid. The initial supply of IAA thus originates from stored pools of IAA-ester conjugates, mainly localized in the embryo itself rather than in the general nutrient storage tissue, the megagametophyte. We have found that de novo synthesis is first induced when the stored pool of conjugated IAA is used up and additional hormone is needed for elongation growth. It is interesting that when de novo synthesis is induced, a distinct induction of catabolic events occurs, indicating that the seedling needs mechanisms to balance synthesis rates for the homeostatic regulation of the IAA pool.  (+info)

(4/76) Low nucleotide diversity at the pal1 locus in the widely distributed Pinus sylvestris.

Nucleotide polymorphism in Scots pine (Pinus sylvestris) was studied in the gene encoding phenylalanine ammonia-lyase (Pal, EC Scots pine, like many other pine species, has a large current population size. The observed levels of inbreeding depression suggest that Scots pine may have a high mutation rate to deleterious alleles. Many Scots pine markers such as isozymes, RFLPs, and microsatellites are highly variable. These observations suggest that the levels of nucleotide variation should be higher than those in other plant species. A 2,045-bp fragment of the pal1 locus was sequenced from five megagametophytes each from a different individual from each of four populations, from northern and southern Finland, central Russia, and northern Spain. There were 12 segregating sites in the locus. The synonymous site overall nucleotide diversity was only 0.0049. In order to compare pal1 with other pine genes, sequence was obtained from two alleles of 11 other loci (total length 4,606 bp). For these, the synonymous nucleotide diversity was 0.0056. These estimates are lower than those from other plants. This is most likely because of a low mutation rate, as estimated from between-pine species synonymous site divergence. In other respects, Scots pine has the characteristics of a species with a large effective population. There was no linkage disequilibrium even between closely linked sites. This resulted in high haplotype diversity (14 different haplotypes among 20 sequences). This could also give rise to high per locus diversity at the protein level. Divergence between populations in the main range was low, whereas an isolated Spanish population had slightly lower diversity and higher divergence than the remaining populations.  (+info)

(5/76) Insect egg deposition induces Pinus sylvestris to attract egg parasitoids.

Plant volatiles released in response to feeding insects are known to attract enemies of the feeding herbivores. In this study, egg deposition by a herbivorous insect was shown to induce a gymnosperm plant to emit volatiles that attract egg parasitoids. Odour from twigs of Pinus sylvestris laden with egg masses of the pine sawfly Diprion pini attracts the eulophid egg parasitoid Chrysonotomyia ruforum. Volatiles released from pine twigs without diprionid eggs are not attractive. Oviposition by the sawfly onto pine needles induces not only a local response in pine needles laden with eggs but also a systemic reaction. Needles without eggs but adjacent to those bearing diprionid eggs also release the volatiles that attract the egg parasitoid. The elicitor of the attractive volatiles was shown to be present in the oviduct secretion coating the eggs of D. pini. When pine twigs are treated with jasmonic acid, a well-known plant wound signal, they emit volatiles that attract the egg parasitoid. These results show, for the first time, that a gymnosperm plant is able to attract parasitoids as soon as a herbivore has deposited its eggs on it. Thus, the plant appears to defend itself against herbivores prior to being damaged by feeding larvae.  (+info)

(6/76) Changes of morphogenic competence in mature Pinus sylvestris L. buds in vitro.

The effects of season and cold storage on morphogenic competence in mature Pinus sylvestris buds were investigated. Peroxidase and polyphenol oxidase activity were measured as markers of oxidative metabolism. No growth in vitro was observed on explants detached from the end of January until the beginning of March. Brachioblasts, each with a couple of needles, formed on 11% of the buds without macrostrobili that were detached in early April and introduced immediately into culture. Of the explants detached in late July, 15% formed shoots with brachioblasts and needles. The lowest activity of peroxidase and polyphenol oxidase in pine buds was observed from the end of April until the beginning of June when morphogenic competence of tissues started to increase. Development of bud explants detached in January was achieved by cold storage for 5 months. Low polyphenol oxidase and peroxidase activity coincided with increased morphogenic potential. Results suggest that reduced or stable activity of peroxidase and polyphenol oxidase is associated with an increased ability of tissues to start growth in vitro.  (+info)

(7/76) Nitrogen fertilizer factory effects on the amino acid and nitrogen content in the needles of Scots pine.

The aim of the research was to evaluate the content of amino acids in the needles of Pinus sylvestris growing in the area affected by a nitrogen fertilizer factory and to compare them with other parameters of needles, trees, and sites. Three young-age stands of Scots pine were selected at a distance of 0.5 km, 5 km, and 17 km from the factory. Examination of the current-year needles in winter of the year 2000 revealed significant (p < 0.05) differences between the site at a 0.5-km distance from the factory and the site at a 17-km distance from the factory--with the site closest to the factory showing the highest concentrations of protein (119%), total arginine (166%), total other amino acids (depending on amino acid, the effect ranged between 119 and 149%), free arginine (771%), other free amino acids (glutamic acid, threonine, serine, lysine--depending on amino acid, the effect ranged between 162 and 234%), also the longest needles, widest diameter, largest surface area, and heaviest dry weight (respectively, 133, 110, 136, and 169%). The gradient of nitrogen concentration in the needles was assessed on the selected plots over the period of 1995-2000, with the highest concentration (depending on year, 119 to 153%) documented in the site located 0.5 km from the factory. Significant correlations were determined between the total amino acid contents (r = 0.448 -0.939, p < 0.05), some free amino acid (arginine, aspartic acid, glutamic acid, lysine, threonine, and serine) contents (r = 0.418 - 0.975, p < 0.05), and air pollutant concentration at the sites, the distance between the sites and the factory, and characteristics of the needles. No correlation was found between free or total arginine content and defoliation or retention of the needles. In conclusion, it was revealed that elevated mean monthly concentration of ammonia (26 microg m(-3)) near the nitrogen fertilizer factory caused changes in nitrogen metabolism, especially increasing (nearly eight times) concentration of free arginine in the needles of Scots pine.  (+info)

(8/76) Patterns of pollen dispersal in a small population of Pinus sylvestris L. revealed by total-exclusion paternity analysis.

Patterns of pollen dispersal were investigated in a small, isolated, relict population of Pinus sylvestris L., consisting of 36 trees. A total-exclusion battery comprising four chloroplast and two nuclear microsatellites (theoretical paternity exclusion probability EP=0.996) was used to assign paternity to 813 seeds, collected from 34 trees in the stand. Long-distance pollen immigration accounted for 4.3% of observed matings. Self-fertilization rate was very high (0.25), compared with typical values in more widespread populations of the species. The average effective pollen dispersal distance within the stand was 48 m (or 83 m excluding selfs). Half of effective pollen was dispersed within 11 m, and 7% beyond 200 m. A strong correlation was found between the distance to the closest tree and the mean mating-distance calculated for single-tree progenies. The effective pollen dispersal distribution showed a leptokurtic shape, with a large and significant departure from that expected under uniform dispersal. A maximum-likelihood procedure was used to fit an individual pollen dispersal distance probability density function (dispersal kernel). The estimated kernel indicated fairly leptokurtic dispersal (shape parameter b=0.67), with an average pollen dispersal distance of 135 m, and 50% of pollen dispersed beyond 30 m. A marked directionality pattern of pollen dispersal was found, mainly caused by the uneven distribution of trees, coupled with restricted dispersal and unequal male success. Overall, results show that the number and distribution of potential pollen donors in small populations may strongly influence the patterns of effective pollen dispersal.  (+info)