Draba Research Articles

FIRST REPORT OF PLEOSPORA TARDA CAUSING LEAF SPOT OF LEPIDIUM DRABA IN IRAN

Since 2009, leaf spot symptoms were observed on Lepidium draba (whitetop) an invasive weed collected in wheat plots (Triticum sp.) in the Hamadan Province of Iran. Typical symptoms included chlorosis of the basal leaves with black discrete ascomata protruding from the leaf surface. Colonies of a fungus recovered from diseases leaves were brown to olivaceous with a white aerial mycelium in the center. Since the morphological characters of this mycete were consistent with the description of Pleospora tarda (Simmons, 1985), its identification was confirmed by amplifying and sequencing the internal transcribed spacer region (ITS) of a representative isolate (GenBank accession No. KC660992). To fulfill Koch’s postulates, a spore suspension (105 ascospores/ml) of the fungus was sprayed onto leaves of whitetop seedlings at the 4-6 leaf stage. Inoculated seedlings were maintained in a growth chamber at 25°C, with more than 75% relative humidity and a 12 h light photoperiod. Inoculated plants showed symptoms like those observed in the field 14 days post inoculation. P. tarda was reisolated from inoculated plants and a culture was deposited in the Iranian Research Institute of Plant Protection with the accession code IRAN 2184C. To our knowledge, this is the first report of P. tarda infecting whitetop in Iran and in the world.

The interrelation between natural enemies of the invasive plant Lepidium draba L., established in a natural pasture in Eastern Romania.

Lepidium draba L. (family Brasicaceae), originally from Europe, is a problematic plant in many agricultural ecosystems in Romania. A literature survey revealed that 196 phytophagous organisms are associated with L. draba, and 80 of them were found during field surveys. In Romania Ceutorhynchus cardariae, Psylliodes wrasei, and Aceria drabae are the most promising biological agents available for controlling L. draba. Observations were made in natural pastures by the Department of Iassy in eastern Romania in 2008. The most common invasive species were Xanthium italicum, Xanthium spinosum, Elaeagnus angustifolia, L. draba, Euphorbia cyparissias, and Verbascum phlomoides, which dramatically decrease ecosystem productivity. Here we present results obtained based on field test-plant relationship phytophagy between L. draba L. and P. wrasei Leonardi and Arnold. We studied plants of the Brasicaceae family: L. draba, L. crenatum, Armoracia rusticana, and Barbarea orthoceras. Test plots comprised four L. draba planted 5 cm apart, with two test plants (L. draba, L. crenatum, B. orthoceras, or A. rusticana) planted at one of three planting distances (30 cm, 15 cm, and 5 cm) on each side of the central plants. Each planting distance variant was repeated four times, and for each variant all observations were made on 16 central L. draba plants and 8 of each test plant: L. draba, L. crenatum, B. orthoceras and A. rusticana. A total of 144 plants was studied: 48 central L. draba plants and 96 of each test species. These results do not contradict previous evidence that oligophagous species P. wrasei controls the L. draba. P. wrasei is also a potential biologic control agent for B. orthoceras (American yellowrocket), which is native to North America, including much of Canada and the western United States, as well as parts of Asia.

4-hydroxybenzyl glucosinolate from Cardaria draba (Cruciferae)

4-hydroxybenzyl glucosinolate from Cardaria draba (Cruciferae)

On the allelopathical effect of some coniferous species

The present paper shows allelopathical effect of different concentrations of an aquous extract from leaves of four coniferous species on the germination of Lepidium draba L. seeds and on the seedlings' growth. Our results prove the seasonal variation of the allelopathical substances metabolically elaborated by different conifers on Lepidium draba seeds germination and seedlings' growth in the first stage of development.