Giorgio Buffa

Chemotaxonomy of Juniperus communis, J. sibirica and J. intermedia

ABSTRACT The oil chemical composition was studied in several populations of Juniperus communis, J. sibirica (J. nana sensu Pignatti) and J. intermedia growing spontaneously in the northwestern Italian Alps. The oil of J. communis was characterized by high percentages of sabinene (32% to 47%) and low values of α-pinene (9% to 22%), whereas J. sibirica showed opposite values (respectively 0.3% to 25% and 9% to 46%). The oil chemical composition of J. intermedia showed intermediate values for both sabinene (28%) and α-pinene (20%) when compared to the other two taxa. The data obtained from GC/MS analyses of the oils were used to study the chemotaxonomic characters of the three taxa. Chemometrics included multivariate statistical analyses such as Principal Component Analysis (PCA), Cluster Analysis (CA) and Discriminant Analysis (DA). The results of this investigation indicated that most of the populations considered as J. intermedia showed a statistically significant different oil composition when compared t...

Soil fungal communities in a young and an old Alnus viridis coenosis

Soil microfungal communities of two ad- jacent, but differently aged Alnus viridis coenoses were studied using the soil dilution plate method. A total of 84 taxa were isolated: 59 from the young com- munity, 51 from the old and 26 taxa shared. Morti- erella parvispora and Pythium sp. had the highest den- sity values in the young and the old alder community, respectively. Species compositions were compared be- tween plots of the two communities using a metric multidimensional scaling and a correspondence anal- ysis. Both analyses grouped plots from the young and the old community separately, suggesting a correla- tion between the changes in the fungal species com- position and the age of the alder communities. The correspondence analysis produced two species groups more related to one set of plots or the other, together with another group formed of Mortierella, Micromucor, Geomyces and Trichoderma species, whose distributions were more closely related to the general abiotic conditions than the age of the alder com- munities. It is proposed that the significant differ- ences in the composition of the two fungal commu- nities mirror the existence of a seral fungal succes- sion paralleling the aging of the alder communities.

The C4 biochemical pathway, and the anatomy of lemongrass (Cymbopogon citratus (DC) Stapf.) cultivated in temperate climates

ABSTRACT Leaf anatomy (light and transmission electron microscopy, immunogold localisation of Rubisco) and physiology (C4 photosynthetic enzyme activities, CO2 assimilation and stomatal conductance) were studied in lemongrass, Cymbopogon citratus (DC) Stapf., cultivated in temperate climates (northwestern Italy). The leaf blade had an NADP-ME Kranz anatomy, with bundle sheath cells containing chloroplasts located in a centrifugal position. Dimorphic chloroplasts, agranal and starchy in the bundle sheath and granal starchless in the mesophyll cells, were also observed. Rubisco, as determined by immunolocalisation, occurred only in the bundle sheath chloroplasts. Pyruvate, orthophosphate dikinase (PPDK), NADP malic dehydrogenase (NADP-MDH), NADP malic enzyme (NADP-ME), PEP-carboxykinase (PCK), and NAD malic enzyme (NAD-ME) activities were also measured, indicating an NADP-ME C4 photosynthetic pathway. Some kinetic properties and chemicalphysical parameters of lemongrass NADP-ME and NADP-MDH as well as CO2 compensation point and stomatal conductance values confirmed these preliminary data. C. citratus appeared to be well adapted to the varying environmental conditions typical of temperate climates, by retaining high NADP-MDH and NADP-ME activities and a low CO2 compensation point.

Evidence for a C4 NADP-ME photosynthetic pathway in Vetiveria zizanioides Stapf

ABSTRACT Leaf anatomy (light and transmission electron microscopy), immunogold localization of Rubisco, photosynthetic enzyme activities, CO2 assimilation and stomatal conductance were studied in Vetiveria zizanioides Stapf., a graminaceous plant native to tropical and subtropical areas, and cultivated in temperate climates (Northwestern Italy). Leaves possess a NADP-ME Kranz anatomy with bundle sheath cells containing chloroplasts located in a centrifugal position. Dimorphic chloroplasts were also observed; they are agranal and starchy in the bundle sheath and granal starchless in the mesophyll cells. Rubisco immunolocalization studies indicate that this enzyme occurs solely in the bundle sheath chloroplasts. Pyruvate-orthophosphate dikinase, NADP-dependent malate dehydrogenase (NADP-MDH), NADP-dependent malic enzyme (NADP-ME), PEP-carboxykinase and NAD-dependent malic enzyme (NAD-ME) activities were determined. Enzyme activity and some kinetic properties of NADP-ME and NADP-MDH as well as CO2 compensation point and stomatal conductance values were calculated indicating a NADP-ME C4 photosynthetic pathway. Biochemical and structural results indicate that V. zizanioides belongs to the C4 NADP-ME variant. This plant appears to be well adapted to the varying environmental conditions typical of temperate climates, by retaining high enzyme activities and a low CO2 compensation point.

Costesia macrocarpa comb. nov. for Funaria macrocarpa (Gigaspermaceae)

Abstract Funaria macrocarpa (Funariaceae) is shown to be an earlier name for Costesia spongiosa (Gigaspermaceae). The species is, however, retained in the genus Costesia and a new combination is hence proposed: Costesia macrocarpa. The species, endemic to central Chile, belongs to the Gigaspermaceae, a small family with six mainly monospecific genera with a widely scattered distribution in the Southern Hemisphere. Both basionyms are lectotypified. A morphological description and a discussion of the geographic distribution of the species are provided.