First Report of Xanthomonas hortorum pv. hederae Causing Bacterial Leaf Spot of Hedera hibernica in Slovenia

In October 2008, water-soaked spots, each 5 to 10 mm in diameter and surrounded by a pale green halo, were observed on leaves of a single Atlantic ivy plant (Hedera hibernica Kirchn.) out of 89 plants imported from the European Union into a commercial greenhouse in Slovenia. Leaves were surface disinfected, and spots were cut and suspended in 10 mM phosphate buffered saline. From this extract, yellow-pigmented, Xanthomonas-like bacterial colonies were isolated onto nutrient agar, and two colonies (NIB Z 1310 and NIB Z 1312) were each identified as a Xanthomonas sp. based on biochemical tests (oxidase negative; positive for hydrolysis of H₂S, starch, and tributyrin; and positive for acid production from sucrose). Both isolates caused a hypersensitive reaction (1) on leaves of tomato cv. Moneymaker. A repetitive extragenic palindromic sequence (REP)-PCR assay using the BOXA1R primer (3) resulted in highly similar DNA fragment banding patterns (Pearson's correlation: 95% identity) between the two isolates (NIB Z 1310 and NIB Z 1312) and the type strain of Xanthomonas hortorum pv. hederae CFBP 4925 (ICMP 453). Partial sequences of the gyrB gene (DNA gyrase, subunit B) (2) from isolates NIB Z 1310 (Accession No. JF794785; 599 bp) and NIB Z 1312 (Accession No. JF794784; 544 bp), showed identical sequences (100% identity with 100% coverage) to type strain ICMP 453 (Accession No. EU498975.1). The pathogenicity of the two isolates from H. hibernica was confirmed on three plants of H. helix 'Evita' (each 6 months old) for each isolate. Plants were sprayed on the abaxial and adaxial side of leaves with 10 ml of a 48-h suspension of the appropriate isolate with approximately 10⁶ CFU/ml (1), covered individually with plastic bags for 24 h, and incubated under high relative humidity (>80%) with 16 h of daylight at 25°C by day and 20°C by night. Three positive and three negative control plants were inoculated with the type strain of X. hortorum pv. hederae CFBP 4925 and 0.01 M magnesium sulfate buffer, respectively. After 21 days, water-soaked spots with a pale green halo were observed on all plants inoculated with the bacterial strains, including the positive control plants. Colonies isolated from these lesions were identical in morphology and BOX-PCR DNA fragment banding patterns to the original isolates. Negative control plants did not develop symptoms, and colonies similar to X. hortorum pv. hederae were not isolated from these plants. To our knowledge, this is the first report of X. hortorum pv. hederae on H. hibernica in greenhouse production in Slovenia. If the disease spreads, it could reduce quality and marketability of this popular ground cover plant. References: (1) Z. Klement et al. Inoculation of Plant Tissues. In: Methods in Phytobacteriology. Akadémiai Kiadó, Budapest, 1990. (2) N. Parkinson et al. Int. J. Syst. Evol. Microbiol. 59:264, 2009. (3) J. Versalovic et al. Methods Mol. Cell Biol. 5:25, 1994.

First Report of Xanthomonas axonopodis pv. poinsettiicola Causing Bacterial Leaf Spot of Euphorbia pulcherrima in Slovenia

In September 2009, water-soaked spots, 2 mm in diameter, surrounded by a pale yellow halo were observed on leaves of pot-grown poinsettia plants (Euphorbia pulcherrima L.) cv. Christmas Feeling in a commercial greenhouse in Slovenia. Several spots per leaf developed on 10% of 84 plants used for propagation and slowly progressed to necrotic brown spots. While all plants were watered by overhead irrigation until mid-September, and afterward by flooding, no symptoms were observed on parent plants of four other separately grown cultivars. Propagated cuttings were all grown together, and in addition to cv. Christmas Feeling, an estimated 90% of 315, 35% of 29, 10% of 240, and 5% of 840 plants of cvs. Crazy Marble Star, Crazy Christmas, Lemon Snow, and Cortez Red, respectively, developed leaf spots. Yellow, smooth, and butyrous colonies with entire margins were isolated from symptomatic leaves of poinsettia parent plants of cv. Christmas Feeling on yeast peptone glucose agar (YPGA). They were identified as a Xanthomonas sp. based on biochemical tests (oxidase negative, positive for hydrolysis of H₂S, starch and tributiryn and acid production from sucrose) and the isolates caused a hypersensitive reaction in leaves of tomato cv. Moneymaker. Partial sequences of gyrase subunit B-like (gyrB) gene (2) from an isolate (Accession No. HQ215596, 676 bp) showed highest similarity to Xanthomonas axonopodis pv. poinsettiicola strain LMG 5401 (Accession No. GU144264.1, 99% identity, 98% coverage) and 98% identity with gyrB sequence of X. axonopodis pv. poinsettiicola pathotype strain LMG 849 (Accession No. GU144273.1, 99% coverage, 3 gaps). Repetitive BOX-PCR (3) revealed high similarity of our isolate to pathotype strain LMG 849 with one additional band of approximate size of 1,500 bp present in our isolate. The pathogenicity of two isolates from parent plants of cv. Christmas Feeling was confirmed on four young poinsettia plants each. Plants were inoculated with a bacterial suspension of approximate concentration of 10⁶ CFU/ml by spraying on the under side and upper side of the leaves, some of which were pricked with a sterile needle (1). Plants were then incubated under high relative air humidity (minimum 85%), 12 h of daylight, and 25°C day and 20°C night temperature regimens. After 10 days, all inoculated plants developed faint leaf spots, consistent with mild symptoms observed in the greenhouse. Colonies isolated from the developed spots had identical morphology and BOX-PCR profile to original isolates. Mock inoculated, negative control plants did not develop characteristic symptoms and no colonies similar to X. axonopodis pv. poinsettiicola were isolated from them. Bacteria isolated from leaf spots of other poinsettia cultivars had the same biochemical characteristics and BOX-PCR profiles as the first isolate. Since no leaf blight was observed on poinsettias in the greenhouse in the previous season and no host plants were kept between the seasons, imported parent plants are the most likely source of infection. To our knowledge, this is the first report of X. axonopodis pv. poinsettiicola on poinsettia in Slovenia, providing further data on the occurrence and potential economic damage of leaf blight of poinsettia in Europe. References: (1) R. A. Lelliott and D. E. Stead. Host tests. In: Methods in Plant Pathology. Vol 2. Blackwell, Oxford, 1987. (2) N. Parkinson et al. Int. J. Syst. Evol. Microbiol. 59, 264, 2009. (3) J. Versalovic et al. Methods Mol. Cell Biol. 5:25, 1994.

Severe or marginal iron deficiency affects spontaneous physical activity in rats

The influence of dietary iron on spontaneous activity was investigated in growing rats. Male rats weighing 97 +/- 10 g fed diets containing 4.6 (deficient), 19.9 (marginal), and 108.4 (adequate) mg Fe/kg diet for 8 wks had hemoglobin values of 52 +/- 6, 152 +/- 4, and 159 +/- 6 g/L, and liver nonheme iron concentrations of 0.79 +/- 0.24, 1.36 +/- 0.39, and 4.58 +/- 0.62 mumol/g, respectively. Body weights were affected only at the lowest iron intake. Diurnal activity was not reversed by iron status; all animals were more active during the dark cycle than the light cycle. Iron deficiency resulted in less time and frequency of horizontal, vertical, and stereotypic movements; less distance moved; and less frequent rotations. Movement speed of iron-deficient rats was faster during early iron deficiency. In the light, rats with marginal iron nutriture were generally more active than were iron-deficient or iron-adequate animals. In the dark, activity generally decreased with each reduction in dietary iron.