Root and Basal Stem Rot of Scotch Broom Caused by Phytophthora citricola and P. drechsleri in Italy

Scotch broom (Cytisus scoparius (L.) Link, Fabaceae), an evergreen shrub native to Europe, is cultivated as a garden plant. In 2003 and 2004, potted plants with symptoms of leaf chlorosis, defoliation, and eventual wilt and associated with root and collar rot were observed in ornamental nurseries in Sicily. As much as 10% of plants were affected in a single nursery. Two species of Phytophthora were consistently isolated alone or together from the same pot with the selective medium of Masago et al. (2). Pure cultures were obtained by single-hypha transfers and the species were identified as P. citricola Sawada (approximately 40% of isolations) and P. drechsleri Tucker (60% of isolations) on the basis of morphological, cultural characters, and electrophoretic phenotype. The isolates of P. drechsleri grew between 10 and 37°C (optimum 27°C) on potato dextrose agar (PDA). The sporangia produced on V8 juice agar (V8A) were ellipsoid to obpyriform, nonpapillate, persistent with internal proliferation, and often forming in a sympodium. Sizes varied, 30 to 60 × 20 to 40 μm (length/width ratio between 1.4 and 2.2). The hyphal swellings were produced in aqueous culture. All isolates were A1 mating type and formed plerotic oospores (mean diameter (ф) 25 μm) with amphigynous antheridia when paired with the A2 reference isolates of P. cryptogea on V8A plus β-sitosterol. The aryl-esterase and malate dehydrogenase isozymes of scotch broom isolates on polyacrylamide slab gels (1) were identical to those of the authentic isolate CBS 292.35 of P. drechsleri and differed from reference cultures of other nonpapillate species. The cardinal temperatures of P. citricola isolates on PDA ranged from 2 to 30°C (optimum 25°C). In liquid culture, the isolates produced irregular-shaped, obovoid to obpyriform sporangia 20 to 70 × 21 to 44 μm that were noncaducous, semipapillate or with inconspicuous papilla, often with two apices. The isolates were homothallic and produced oospores (mean ф 22 μm) with paragynous antheridia. The electrophoretic phenotype of these isolates was identical to the phenotype of P. citricola reference isolates and very different from that of the reference isolates of other semipapillate species. The pathogenicity tests of the representative isolates of P. drechsleri (IMI 391710) and P. citricola (IMI 391715) were carried out in a screenhouse. Twenty 3-month-old scotch broom seedlings were transplanted into pots (12 cm ф) filled with soil infested with the inoculum produced on a mixture of vermiculite and autoclaved oat seeds. The plants were maintained at 20 to 28°C and watered to field capacity once a week. After 30 to 40 days, all inoculated plants showed symptoms of wilting and root rot. The 20 control plants transplanted into pots containing noninfested soil remained healthy. P. citricola and P. drechsleri were reisolated from infected tissues. To our knowledge, this is the first report of P. citricola and P. drechsleri on scotch broom. A root rot of scotch broom caused by P. megasperma has been reported in central Italy (3). References: (1) S. O. Cacciola et al. Plant Dis. 86:327, 2002. (2) D. C Erwin and O. K. Ribeiro. Pages 39–41 in: Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) A. M. Vettraino and A. Vannini. Plant Pathol. 53:417, 2003.

First Report of Septoria Spot on Bergamot

More than 95% of bergamot (Citrus bergamia Risso & Poit) essence production utilized in the international perfume industry comes from the coastal growing area in the Province of Reggio di Calabria in the Calabria Region of southern Italy. Fruit and leaf spots were observed on bergamot cv. Fantastico in some orchards during February and March 2001. Symptoms affected ≈20% of the fruits and resembled those caused by Septoria citri Pass. on lemon in the nearby Sicily Region (2). Symptoms on fruits were characterized by reddish-brown pits, 1 to 2 mm in diameter, often in proximity, and extending no deeper than the flavedo; or characterized by larger confluent brown spots, sunken and extending into the albedo. Leaf symptoms occurred on both sides of the blade and were characterized by irregular brown spots surrounded by a yellow halo. Spherical, dark-walled pycnidia were observed on brown spots on fruits. Pycnidia contained hyaline, nonseptate, or 1 to 3 septate, cylindrical conidia, rounded at the apex, measuring 8 to 18 × 1.5 to 2.0 μm (8 to 29 × 1.5 to 2.0 μm in pure culture), differing from the tapered conidia of S. citri. The fungus was subsequently identified as S. limonum Pass., a species first described in the 19th century on lemon in unheated glasshouses in northern Italy and later reported from other countries (3). It is still an open question whether S. limonum is distinct from S. citri. Previously, in fact, different species of Septoria from citrus have been considered synonyms of S. citri on the basis of isozyme electrophoretic phenotype (1). The fungus was isolated on artificial media from infected leaf and fruit tissues (pits and larger spots). Brown spot symptoms were reproduced by artificial inoculation of detached bergamot fruits. A spore suspension (1 × 106 spores per ml) of the fungus was sprayed on fruit wounded by a needle (1 mm in diameter) to a depth of 2 mm and washed in sterile water. After inoculation, the fruits were incubated 10 days at 22°C and 100% relative humidity. The fungus was reisolated from inoculated tissues. The damage caused by this disease appears to be more important on bergamot than on other citrus fruits since it affects oil-bearing tissue and consequently the production of essential oil. References: (1) M. R. Bonde et al. Phytopathology 81:517, 1991. (2) S. Grasso and R. La Rosa. Riv. Patol. Veg. 19:15, 1983. (3) L. J. Klotz. Color Handbook of Citrus Diseases, 4th ed. University of California, Division of Agricultural Sciences, Berkeley, 1973.

Silver-stained phenotyping of alpha 1-antitrypsin in dried blood and serum specimens.

In this technique for determining the electrophoretic phenotype of alpha 1-antitrypsin in dried blood or serum specimens, the adsorbed material is eluted with a concentrated solution of dithiothreitol, focused on polyacrylamide thin-layer gel, and made visible with silver stain. With this staining technique all normal and pathological alpha 1-antitrypsin phenotypes can be detected. The procedure is relatively simple, inexpensive, and suitable for use in large-scale screening for alpha 1-antitrypsin deficiency in selected populations.

Studies on Metatherian Sex Chromosomes I. Inheritance and Inactivation of Sex-linked Allelic Genes determining Glucose-6-phosphate Dehydrogenase Variation in Kangaroos

Wallaroos (Macropus robustus robustus), which have the G6PD-F electrophoretic phenotype, crossed with euros (M. r. erubescens), ofG6PD-S phenotype, produced F 1 animals which had only the maternal G6PD type regardless of the direction of the cross. When F 1 hybrids were backcrossed to wallaroos or euros, backcross progeny of either parental phenotype resulted. Sex-linked inheritance of allelic G6PD genes is shown to occur in wallaroos, euros and red kangaroos (M. rufus). Dose compensation for X chromosomes at the G6PD locus in kangaroos is achieved by inactivation of the allele of male parental origin.

Phenotypic Variation in the Lake Whitefish, Coregonus clupeaformis, Induced by Introduction into a New Environment

Adult lake whitefish (Coregonus clupeaformis) from Clearwater Lake and second generation adults of offspring from Clearwater whitefish transplanted to Lyons Lake were compared with respect to morphometric and meristic characters and isozymes of L-glycerol-3-phosphate dehydrogenase (GPDH). Feeding habits and abundance of pelagic and benthic foods were compared in the two lakes.Gill raker number, lateral line scale count, and interorbital width remained constant between parental and offspring populations. Gill raker length was the main character found to differ between the populations. This was found to be related to the percentage and type of benthic food eaten. Abrasion of the gill rakers is offered as an explanation for the differences in gill raker length. Differences were found in various other meristic and morphological characters, as well as in electrophoretic phenotype frequencies of isozymes of GPDH.