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PubMed1997

A comparison of population differentiation across four classes of gene marker in limber pine (Pinus flexilis James).

We examined genetic differentiation among seven populations of limber pine using four classes of gene marker. Among-population differentiation was much higher for maternally inherited mitochondrial DNA polymorphisms than for paternally inherited chloroplast DNA, indicating that wind-dispersed pollen is the main agent of gene flow. Chloroplast DNA differentiation is consistent with gene flow estimated in a prior paternity analysis. Using the estimates of seed and pollen flow derived from mtDNA and cpDNA differentiation, we predicted the value of Fst expected at nuclear loci. Allelic frequency differentiation at seven allozyme loci was relatively homogeneous across loci and consistent with the level of differentiation predicted from the organellar haplotypes. By contrast four of the nine randomly applied polymorphic DNA (RAPD) markers we examined were more strongly differentiated than this prediction, suggesting the action of diversifying selection. However, the differentiated RAPDs and mtDNA were concordant in dividing the populations into two groups, suggesting some historical division. Simulations show that such historical division can increase the interlocus variance in Fst, but neither a historical nor an equilibrium model could account for the joint distribution of Fst estimates across both allozyme and RAPD loci. Thus at least one group of loci appears to be experiencing natural selection.

Animals↗
PubMed2001

Drought differentially affects expression of a PR-10 protein, in needles of maritime pine (Pinus pinaster Ait.) seedlings.

A full length cDNA encoding a PR-10 protein was isolated from maritime pine drought-stressed seedlings. The predicted protein contained 150 amino acids, has a molecular mass of 16.7 kDa and an isoelectric point of 5.28. The transcript level of PR-10 displayed a transient accumulation in needles of drought-stressed plants, and was not detectable in root and stem tissues.

Amino Acid Sequence↗
PubMed1996

Seasonal variation of western white pine (Pinus monticola D. Don) foliage proteins.

Recently, a western white pine protein, Pin m III, was shown to be associated with overwintering and frost hardiness of western white pine foliage. To examine whether Pin m III is directly involved in frost hardiness by functioning as an antifreeze protein, work is underway to clone the gene encoding this protein and to assess the function of this gene in freezing tolerance by incorporating the gene in a test plant, such as tobacco. Here, we examined in more detail, by SDS-PAGE and also by two dimensional gel electrophoresis, the seasonal variation of additional proteins in western pine foliage. SDS-PAGE analysis of three seedlots showed that different proteins reached a maximum level in different months, although most proteins (5 to 11) reached a maximum level in winter months (December, January and February). The 2-D gel analysis of foliage sampled on three harvest dates (October, January and April) of one seedlot revealed a seasonal variation of a large number proteins (76 to 184). Of the seasonally varied proteins, the amino terminal sequence of several proteins including Pin m III was determined. One of the sequences was identified by homology to that of the small subunit of ribulose biphosphate carboxylase, whose level increased substantially from fall to spring. The amino terminal sequence of Pin m III had 89% homology to a sugar pine protein, Pin l I. The anti-photosystem II antibody was used to monitor the annual variation of the extrinsic 23-kDa photosystem II protein. The level of the extrinsic 23-kDa photosystem II protein decreased slowly as fall progressed and reached its lowest level in December and then increased in early spring indicating that this variation is due to photosynthetic activity of the foliage during the season.

Amino Acid Sequence↗
PubMed1992

Pressure-volume analysis of tissue water relations parameters for individual fascicles of loblolly pine (Pinus taeda L.).

A technique was tested for obtaining water relations parameters from individual fascicles of loblolly pine needles by the pressure-volume curve method. Comparisons were made between parameters derived from (1) individual fascicles that were rehydrated in a pressure chamber after being removed from the shoot and (2) fascicles that were rehydrated on the shoot. Estimates of tissue osmotic potential for needles rehydrated by the two methods were significantly different for needles from terminal shoots, but not significantly different for needles from lateral shoots. Similarly, a significant difference in the estimated tissue elasticity at zero water potential was noted for needles on terminal shoots, but not for those on lateral shoots. It is suggested that differences due to rehydration method are related to the duration of the rehydration period and not the choice of technique. The use of fascicles of needles, rehydrated after detachment, allows repeated estimation of the tissue water relations of a single conifer shoot.

Journal Article↗
PubMed1994

Boric acid-phenolic relationships within the Pinus echinata-Pisolithus tinctorius ectomycorrhizal association.

At germination, container-grown shortleaf pine seedlings were inoculated with Pisolithus tinctorius (Pers.) Coker & Couch or left uninoculated, and both groups were fertilized semiweekly with a modified Hoagland's solution supplemented with 0 or 0.4 mM boric acid. After 12, 16 and 24 weeks, seedling root tissue was analyzed for ectomycorrhizal colonization, phenolic concentration and phenoloxidase activity. In addition, phenoloxidase activity was assayed in P. tinctorius that had been cultured in a liquid medium containing boric acid. Inoculation with P. tinctorius increased the root phenolic concentration of 16- and 24-week-old seedlings, and increased root phenoloxidase activity in 12-, 16- and 24-week-old seedlings. Fertilization with boric acid reduced the phenolic concentration of P. tinctorius ectomycorrhizae after 24 weeks. Although boric acid fertilization did not affect the phenoloxidase activity of 12-, 16- and 24-week-old inoculated roots, or that of 16- and 24-week-old uninoculated roots, it increased the phenoloxidase activity of P. tinctorius grown in vitro and 12-week-old uninoculated roots. We conclude that boric acid fertilization influences the phenolic relations of the shortleaf pine-P. tinctorius ectomycorrhizal association, possibly through a boric acid-induced increase in phenoloxidase activity.

Journal Article↗
PubMedDate not supplied

Carbon allocation, gas exchange, and needle morphology of Pinus ponderosa genotypes known to differ in growth and survival under imposed drought.

Seedlings from 27 open-pollinated families of ponderosa pine representing nine geographically diverse origins were screened for drought tolerance based on survival and growth under imposed drought. Seedlings that had been preconditioned to drought survived 14 days longer than seedlings that had been well watered before being subjected to drought. Seed sources varied in their ability to survive drought and this variation was accentuated by drought preconditioning. Seedlings from a South Dakota source and a Nebraska source generally survived the longest under drought. Seedlings from a Montana source and a New Mexico source succumbed the fastest after water was withheld. Significant family within source variation in drought survival was observed for some sources. In general, drought survival was poorly correlated to climate indices of the seed sources. Allocation of biomass to roots, stems, and needles varied significantly among the seed sources with the most drought-sensitive sources (Montana and New Mexico) showing the most divergent allocation patterns. The relation between drought survival and shoot/root ratio suggested that there is an optimum pattern of allocation for drought survival. A comparison of the most and least drought-tolerant sources indicated that needle gas exchange (net photosynthesis and needle conductance to water vapor) and predawn needle water potential were similar among the sources regardless of their relative ability to survive drought. Needle morphology traits often associated with variation in drought tolerance, such as stomatal density and specific leaf area, did not differ among the seed sources. However, seedlings from the drought-tolerant sources had shorter needles, less surface area per needle, and fewer stomata per needle than seedlings from the drought-sensitive sources. The results suggest that drought tolerance of ponderosa pine may be improved through seed source selection and, within certain sources, family selection. Allocation patterns and needle morphology appear to play a larger role than needle gas exchange patterns in determining drought tolerance in this species.

Journal Article↗
PubMedDate not supplied

Effects of leaf nutrient status on photosynthetic capacity in loblolly pine (Pinus taeda L.) seedlings grown in elevated atmospheric CO(2).

We measured needle photosynthesis of loblolly pine seedlings grown in a factorial experiment with two CO(2) partial pressures (35 and 65 Pa) and three nutrient treatments (7 mM NH(4)NO(3) + 1 mM PO(4); 7 mM NH(4)NO(3) + 0.2 mM PO(4); 1 mM NH(4)NO(3) + 1 mM PO(4)). The data were used to parameterize a physiologically based photosynthetic model that included limitations imposed by ribulose-1,5-bisphosphate carboxylase/oxygenase activity, electron transport capacity and inorganic phosphate availability. With nonlimiting nutrients, seedlings grown at 65 Pa CO(2) had significantly higher net photosynthesis and lower stomatal conductance than seedlings grown at 35 Pa CO(2). Nutrient limitations by either N or P significantly reduced photosynthetic capacity. When either N or P was limiting, there was no effect of growth CO(2) partial pressure on photosynthesis, but stomatal conductance was significantly lower for seedlings grown at 65 Pa CO(2). Modeled biochemical parameters suggest that, in all cases, photosynthesis was co-limited by carboxylation, electron transport and phosphate regeneration. Acclimation to growth in elevated CO(2) involved a reduction in leaf N content. In the low-N and low-P treatments, modeled parameters indicated that the biochemical processes of photosynthesis were down regulated to the point that there was no effect of increasing CO(2) partial pressure. The capacity to regenerate phosphate was reduced in both low nutrient treatments, but was only reduced by elevated CO(2) when seedlings were grown under low soil P conditions. Increased photosynthetic water use efficiency and nutrient use efficiency in response to CO(2) enrichment occurred in all three nutrient treatments and have important implications for whole-plant water and nutrient balance. These data support the contention that soil nutrient status in forest ecosystems will be a critical influence on tree seedling response to increasing atmospheric CO(2) partial pressures.

Journal Article↗
PubMedDate not supplied

Adaptation to climatic changes of the timing of bud burst in populations of Pinus sylvestris L. and Picea abies (L.) Karst.

To assess the long-term effects of the projected climatic change on Scots pine and Norway spruce in Finland, observations were made on the timing of bud burst in provenance experiments established in 1931-1932 and in 1978. Significant differences in the timing of bud burst were found between seed origins. The northernmost origins flushed earlier than origins from southern regions. However, no correlation was found between the effective temperature sum at which bud burst took place and the annual mean temperature sum at the original location, probably because the experiments included origins from southerly high-altitude sites. When the degree days before bud burst in the 1931 and 1978 Norway spruce experiments at Punkaharju were compared, it appeared that, in the older experiment, the populations had adapted to the environment at the new site as a result of selective thinning.

Journal Article↗