First Report of Powdery Mildew of Blackberry Caused by Podosphaera aphanis in Serbia

Blackberries (Rubus L. subgenus Rubus Watson) are popular wild fruits with a high content of antioxidants and thus beneficial effect on human health (Reyes-Carmona et al. 2005). In July 2019 and May 2020, plants with typical powdery mildew symptoms were collected in the blackberry cultivar ‘Triple Crown’ orchard (2 ha) in the vicinity of Pakovraće (Moravica District, Serbia). The symptoms observed in 2019 included mild chlorotic spots on both old and young leaves accompanied by white powdery mildew colonies on the surface of the leaves, visible on both primocanes and floricanes. In 2020, even more intensive symptoms occurred on fruit-bearing shoots, which were covered with dense white fungal growth. Heavily infected leaves turned necrotic along the edges, followed by defoliation. Disease incidence was calculated by randomly counting and rating 100 plants in four replications and estimated to be over 90%, and disease severity was estimated to be over 40%. Morphological characteristics were assessed using bright-field and phase-contrast microscopy (Jankovics et al. 2011) and revealed the presence of unbranched, erect conidiophores (n = 50, 75 to 200 μm) with a cylindrical foot cell and up to five short cells. Conidia were unicellular, hyaline, and ellipsoid-barrel-shaped (n = 50, 22.5 to 35.5 × 12.5 to 15 μm) containing fibrosin bodies (in 3% KOH). All observed characteristics resembled Podosphaera spp. (Braun and Takamatsu 2000). The presence of chasmothecia was not recorded. Further molecular identification was conducted using internal transcribed spacer sequence analysis of two isolates, 420G-19 and 30G-20, sampled in 2019 and 2020, respectively. Total DNA was extracted directly from epiphytic mycelium on the leaves using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) following the manufacturer’s instructions. Polymerase chain reaction amplification and sequencing were performed with primers ITS1F and ITS4 (Takamatsu et al. 2010). The nucleotide sequence of the representative isolates 420G-19 (530 bp) and 30G-20 (530 bp) (accession nos. MN914995 and MT514661) shared 100% identity, and both shared 99.49 to 99.81% nt identity with 32 Podosphaera aphanis strawberry and raspberry isolates in GenBank (the highest 99.81% with GU942455, Harvey and Xu 2010), confirming that powdery mildew of blackberry in Serbia is caused by P. aphanis. To fulfill Koch’s postulates, 10 rooted, healthy blackberry plants (cv. Triple Crown) were dusted with conidia of isolate 30G-20 and incubated at 23°C under high relative humidity in the glasshouse. Healthy blackberry plants incubated in the same conditions served as a negative control. Minute white fungal colonies sharing the same microscopic features with the original isolate were visible 7 to 8 days postinoculation on all inoculated plants. No fungal growth was observed in the negative control. Serbia is the fourth largest blackberry producer in the world (Strik et al. 2007), and the occurrence of P. aphanis causing powdery mildew as a new pathogen is of utmost importance. P. aphanis is described as a strawberry and raspberry powdery mildew pathogen with a population expressing substantial genetic diversity (Harvey and Xu 2010). The molecular data on blackberry-originating isolates of P. aphanis are missing. Our study showed that P. aphanis could be destructive for blackberry in Serbia, thus representing a threat for the production of these valuable crops

Identification of phytoplasmas belonging to aster yellows ribosomal group (16SrI) in vegetables in Serbia.

Leaf and root samples of carrot, and flower samples of broccoli with symptoms referable to phytoplasma presence were collected and tested for phytoplasma presence. Detection, identification and molecular characterization were performed on 16S rDNA, Tuf, rpS3, putative aminoacid kinase and putative DNA helicase phytoplasma genes. Analyses of all five DNA fragments showed that carrot was infected with aster yellows phytoplasmas belonging to ribosomal subgroups 16SrI-A and 16SrI-B and broccoli only with phytoplasmas belonging to ribosomal subgroup 16SrI-B

Lamium maculatum is a Natural Host for Cucumber mosaic virus

Lamium maculatum L. (spotted dead-nettle) is a flowering perennial ornamental that is commonly grown as a landscape plant for an effective ground cover. In June 2010, severe mosaic accompanied by reddish brown necrosis and leaf deformation was noticed on 80% of L. maculatum growing in shade under trees and shrubs in Sarajevo (Bosnia and Herzegovina). Leaves from 10 symptomatic L. maculatum plants were sampled and analyzed by double-antibody sandwich (DAS)-ELISA using commercial diagnostic kits (Bioreba AG, Reinach, Switzerland) against Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV), and Impatiens necrotic spot virus (INSV), the most important viral pathogens of ornamental plants (1,2). Commercial positive and negative controls and extracts from healthy L. maculatum leaves were included in each assay. All samples tested negative for TSWV and INSV and positive for CMV. The virus was mechanically transmitted to test plants and young virus-free plants of L. maculatum using 0.01 M phosphate buffer (pH 7). The virus caused chlorotic local lesions on Chenopodium quinoa, while systemic mosaic was observed on Capsicum annuum ‘Rotund,’ Nicotiana rustica, N. glutinosa, N. tabacum ‘White Burley,’ and Phaseolus vulgaris ‘Top Crop.’ The virus was transmitted mechanically to L. maculatum and induced symptoms resembling those observed on the source plants. Inoculated plants were assayed by DAS-ELISA and all five inoculated plants of each species tested positive for CMV. The presence of CMV in L. maculatum as well as mechanically infected N. glutinosa plants was further confirmed by RT-PCR. Total RNA from symptomatic leaves was isolated using RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and RT-PCR was performed with the One-Step RT-PCR Kit (Qiagen) following the manufacturer's instructions. The primer pair, CMVAu1u/CMVAu2d, that amplifies the entire coat protein (CP) gene and part of 3′- and 5′-UTRs was used for both amplification and sequencing (4). Total RNA obtained from the Serbian CMV isolate from pumpkin (GenBank Accession No. HM065510) and a healthy L. maculatum plant were used as positive and negative controls, respectively. All naturally and mechanically infected plants as well as the positive control yielded an amplicon of the expected size (850 bp). No amplicon was observed in the healthy control. The amplified product derived from isolate 3-Lam was purified (QIAquick PCR Purification Kit, Qiagen), directly sequenced in both directions and deposited in GenBank (JX436358). Sequence analysis of the CP open reading frame (657 nt), conducted with MEGA5 software, revealed that the isolate 3-Lam showed the highest nucleotide identity of 99.4% (99.1% amino acid identity) with CMV isolates from Serbia, Australia, and the USA (GQ340670, U22821, and U20668, respectively). To our knowledge, this is the first report of the natural occurrence of CMV on L. maculatum worldwide and it adds a new host to over 1,241 species (101 plant families) infected by this virus (3). This is also an important discovery for the ornamental industry since L. maculatum is commonly grown together with other ornamental hosts of CMV in nurseries and the urban environment as well as in natural ecosystems. References: (1) Y. K. Chen et al. Arch. Virol. 146:1631, 2001. (2) M. L. Daughtrey et al. Plant Dis. 81:1220, 1997. (3) M. Jacquemond. Adv. Virus Res. 84:439, 2012. (4) I. Stankovic et al. Acta Virol. 55:337, 2011. </jats:p

The Right to Development in International Law: New Momentum Thirty Years Down the Line?

The right to development (RTD) is contested in international law, politics and practice. This remains the case, despite the 30-year existence of the United Nations Declaration on the Right to Development (UNDRTD), the many substantive leads that current international law provides, and the renewed inspiration that can be drawn from Agenda 2030 and its sustainable development goals. This article explores whether there is a possible new momentum for the RTD in international law. Deep substantive and political divisions about the exact content and implications of the RTD prevail between—and within—the North and the South. Up to now these divisions have stood in the way of achieving greater normative clarity, follow-up and implementation action. This state of affairs has directed us to adopt a pragmatic approach, by which we consider the scope for revitalizing the RTD through existing provisions of international law, rather than by creating additional normative frameworks. Thus, after a short sketch of the historical evolution of the RTD, we examine the nature, substance and implications of this right as conceived in the UNDRTD. Then, we pursue the question of how existing provisions of international law could be mobilized mor