Carbon, hydrogen and oxygen stable isotope ratios of whole wood, cellulose and lignin methoxyl groups of Picea abies as climate proxies.

RATIONALE: Carbon, hydrogen and oxygen (C, H and O) stable isotope ratios of whole wood and components are commonly used as paleoclimate proxies. In this work we consider eight different proxies in order to discover the most suitable wood component and stable isotope ratio to provide the strongest climate signal in Picea abies in a southeastern Alpine region (Trentino, Italy). METHODS: δ(13)C, δ(18)O and δ(2)H values in whole wood and cellulose, and δ(13)C and δ(2)H values in lignin methoxyl groups were measured. Analysis was performed using an Isotopic Ratio Mass Spectrometer coupled with an Elemental Analyser for measuring (13)C/(12)C and a Pyrolyser for measuring (2)H/(1)H and (18)O/(16)O. The data were evaluated by Principal Component Analysis, and a simple Pearson's correlation between isotope chronologies and climatic features, and multiple linear regression were performed to evaluate the data. RESULTS: Each stable isotope ratio in cellulose and lignin methoxyl differs significantly from the same stable isotope ratio in whole wood, the values begin higher in cellulose and lignin except for the lignin δ(2)H values. Significant correlations were found between the whole wood and the cellulose fractions for each isotope ratio. Overall, the highest correlations with temperature were found with the δ(18)O and δ(2)H values in whole wood, whereas no significant correlations were found between isotope proxies and precipitation. CONCLUSIONS: δ(18)O and δ(2)H values in whole wood provide the best temperature signals in Picea abies in the northern Italian study area. Extraction of cellulose and lignin and analysis of other isotopic ratios do not seem to be necessary.

[Testing of microsatellite primers with different populations of Eurasian spruces Picea abies (L.) Karst. and Picea obovata Ledeb].

From a clone library containing microsatellite DNA fragments of Norwegian spruce, seven pairs of primers were selected. These primers were tested to be the markers in the genetic structure analysis of nine populations of Eurasian spruce species Picea abies (L.) Karst. and Picea obovata Ledeb. Five pairs of these primers identified polymorphic loci with the allele numbers from 6 to 15. In the populations examined, the observed and expected heterozygosity values assessed at five loci varied from 0.1778 to 0.6556 and from 0.7800 to 0.900, respectively. In the populations examined, the values of F(st) index varied from 0.0691 to 0.2551 with the mean value of 0.1318. On the dendrogram based on Nei genetic distances, the populations formed three groups: Pskov-Ciscarpathia, Komi-Tatarstan-Arkhangelsk, Kazakhstan-Karelia(natural)-Karelia(culture)-Krasnoyarsk. Five of the primer pairs tested proved useful for analysis of the population genetic structure in Eurasian spruce species.

Is Cupressus sempervirens native in Italy? An answer from genetic and palaeobotanical data.

This study represents the first large-scale analysis using nuclear molecular markers to assess genetic diversity and structure of Cupressus sempervirens L.. Genetic and fossil data were combined to infer the possible role of human activity and evolutionary history in shaping the diversity of cypress populations. We analysed 30 populations with six polymorphic nuclear microsatellite markers. Dramatic reductions in heterozygosity and allelic richness were observed from east to west across the species range. Structure analysis assigned individuals to two main groups separating central Mediterranean and eastern populations. The two main groups could be further divided into five subgroups which showed the following geographical distributions: Turkey with the Greek islands Rhodes and Samos, Greece (Crete), Southern Italy, Northern Italy, Tunisia with Central Italy. This pattern of genetic structure is also supported by SAMOVA and Barrier analyses. Palaeobotanical data indicated that Cupressus was present in Italy in the Pliocene, Pleistocene and Holocene. Furthermore, our molecular survey showed that Italian cypress populations experienced bottlenecks that resulted in reduced genetic diversity and allelic richness and greater genetic differentiation. Recent colonization or introduction may also have influenced levels of diversity detected in the Italian populations, as most individuals found in this range today have multilocus genotypes that are also present in the eastern range of the species. The data reveal a new interpretation of the history of cypress distribution characterized by ancient eastern populations (Turkey and Greek islands) and a mosaic of recently introduced trees and remnants of ancient, depauperate populations in the central Mediterranean range.

Mycosphaerella dearnessii, a Needle-cast Pathogen on Mountain Pine (Pinus mugo) in Italy.

The pathogen Mycosphaerella dearnessii Barr. (syn. Scirrhia acicola; anamorph Lecanosticta acicola), the causal agent of brown spot needle blight, was observed on Pinus mugo in the Botanical Garden in Gardone (Brescia), on the western side of Garda Lake in northeastern Italy. Symptoms were first noticed in the spring of 1997 by Klaus Lang (University of Freising, Germany). Two years later, all 12 of the P. mugo present in the Garden exhibited extensive necrosis, and defoliation of the crown starting from the bottom upward was more prevalent on the shaded portion of infected trees. The trees were about 50 years old and 2.0 to 2.5 m in height. Symptomatic needles were confined to the 2- and 3-year old internodes. Infected needles had several dark to purplish-brown spots surrounded by green tissue and usually had dead tips. Pycnidia and conidia of Lecanosticta acicola were observed. Conidia were 4-celled, curved, pointed at one end and blunt at the other, pale olive-brown and 20 to 30 × 3 to 4 µm. The fungus was isolated in pure culture. The pathogen causes serious losses in China, eastern United States, and central and South America, but was observed for the first time in Europe only 30 years ago. It is a major cause of needle blight on several European pine species, especially P. sylvestris, P. nigra, and P. mugo. In the last 7 years, there have been reports of the fungus in pine stands, first in France, Aquitaine, and the western Pyrenees on P. radiata (3), and more recently on P. mugo in the Alps in Austria (1), Switzerland (2), and southern Germany (4). This record of the fungus near Lake Garda poses a new serious threat especially for the pine plantations of P. nigra and P. sylvestris in the more humid locations in the Alps, Apennines, and elsewhere in the mountains of southern Europe where the climatic conditions are similar to that of central Europe. This is the first report of M. dearnessii on the southern slopes of the Alps and in Italy. References: (1) M. Brandstetter and T. Cech. Oesterreichische Forstzeitung 110:35, 1999. (2) O. Holdenrieder and T. N. Sieber. Eur. J. For. Pathol. 25:293, 1995. (3) A. Levy and C. Lafaurie. Phytoma 463:33, 1994. (4) L. Pehl L. Nachrichtenbl. Dtsch. Pflanzenschutzdienstes 47:305, 1995.