Enhancement of the resistance level in plants by rhizobacteria has been proven in several pathosystems. This study investigated the ability of four rhizobacteria strains (Pseudomonas putida BTP1 and Bacillus subtilis Bs2500, Bs2504 and Bs2508) to promote the growth in three barley genotypes and protect them against Cochliobolus sativus. Our results demonstrated that all tested rhizobacteria strains had a protective effect on barley genotypes Arabi Abiad, Banteng and WI2291. However, P. putida BTP1 and B. subtilis Bs2508 strains were the most effective as they reduced disease incidence by 53 and 38% (mean effect), respectively. On the other hand, there were significant differences among the rhizobacteria-treated genotypes on plant growth parameters, such as wet weight, dry weight, plant height and number of leaves. Pseudomonas putida BTP1 strain was the most effective as it significantly increased plant growth by 15-32%. In addition, the susceptible genotypes Arabi Abiad and WI2291 were the most responsive to rhizobacteria. This means that these genotypes have a high potential for increase of their resistance against the pathogen and enhancement of plant growth after the application of rhizobacteria. Consequently, barley seed treatment with the tested rhizobacteria could be considered as an effective biocontrol method against C. sativus.
This study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.
The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is the major pest of olives worldwide. The figitid wasp, Aganaspis daci (Hymenoptera: Figitidae), is a larval-prepupal endoparasitoid of fruit fly species, and it was found to successfully parasitize medfly larvae in field-infested figs in Greece. To assess the potential of A. daci as a biological control agent against B. oleae, we studied the effect of olive fruit size on parasitism rates of A. daci on 2nd and 3rd instar larvae of B. oleae, by using fruit of different size (cultivar ‘Chalkidikis’) and wild olive fruit. In addition, we conducted releases of A. daci females in a pilot olive grove in Volos, Magnesia. From July to October, we released 200 A. daci females/0.1 ha/week, followed by olive fruit sampling to estimate olive fruit infestation levels and the parasitism rates of A. daci. Laboratory trials revealed that fruit size and larvae instar were predictors of parasitism success of A. daci, with parasitism rates higher for small-size fruit of the cultivar “Chalkidikis” and the 3rd instar larvae of B. oleae. In field trials, no A. daci adults emerged from the olive fly infested fruit.
Root-knot nematodes (RKN), Meloidogyne spp., have a wide host range and are common in the Mediterranean area. Cultivated lavender (Lavandula angustifolia) was found naturally infested by M. hapla in Kozani area, the first documented infestation of this crop by RKN in Greece. Oxalis pescaprae, a common winter weed in Crete, was found to be a host of M. javanica under artificial inoculation. This weed acts as a potential winter host of the nematode in fields cultivated with vegetable crops. Two populations of M. ethiopica were found in kiwi and maize in Greece in the past. Recently, populations of M. ethiopica from Europe were re-classified as M. luci, based only on the population isolated from kiwi for Greece. In the current work, the RKN populations originating from kiwi and maize and maintained on tomato, were identified as M. luci. Nematode species identification was determined by electrophoretic analysis of protein extracts obtained from females.
Phenology and parasitism of the scale insect, Coccus pseudomagnoliarum (Kuwana) (Hemiptera: Coccomorpha: Coccidae), infesting Citrus sinensis (Rutaceae), were studied in Papagou area, in northeastern Athens, from June 2015 to June 2017. Coccus pseudomagnoliarum is a univoltine, viviparous, parthenogenetic species. It overwintered as settled 1st instar nymph on the shoots of the trees. The 2nd instar nymphs appeared between the beginning of April and the end of May, and the mature females were recorded from the beginning of May until the middle of June. The crawlers appeared between the middle of May and the middle of June and the 1st instar nymphs settled on the shoots at the end of May, where they remained during the whole summer period, winter, until the beginning of April next year. Parasitism of the scale was recorded between the beginning of May and the middle of May and reached a maximum rate of 35%. The recorded parasitoid species were Coccophagus shillongensis Hayat and Singh (Hymenoptera: Aphelinidae), Coccophagus spp. and Metaphycus dispar (Mercet) (Hymenoptera: Encyrtidae).
Multiple abnormal individuals of Ecklonia stolonifera with thalli that developed numerous shoot-like structures on the lateral blades were found in two littoral regions of Nakanoshima in the Oki Islands, Shimane Prefecture, Japan. Except for the presence of these diagnostic structures, no other morphological differences were observed between the abnormal and normal individuals. The development of the shoot-like structures isolated from the lateral blade was the same as that of typical vegetative reproductive sporophytes that formed on stolons. In the abnormal individuals, when cultivation was performed using zoospores, the shoot-like structures were observed on the progeny after 18 months of culture and 20.0% of individuals exhibited these structures.
Fifteen attached macroalgae from the Madeira Archipelago, comprising three green, three red and nine brown algal species, as well as two beach-cast macroalgal samples, collected along the north shore of Gran Canaria, were assessed for their biochemical properties. The analysis included the determination of total minerals, total carbohydrates, protein, lipids, chlorophyll a, total carotenoids, total phenolic content, fucoxanthin and phycobilins (allophycocyanin, phycocyanin and phycoerythrin). The results showed a high variability of biochemical composition, allowing for the targetting of specific bioresources for particular purposes, including functional foods. This work provides the foundation for a biorefinery strategy implementation plan, for which specific macroalgae may be targeted for valuable and beneficial compounds.
This review article explores the state of DNA barcoding of macroalgae in the Mediterranean Sea. Data from the Barcode of Life Data System (BOLD) were utilised in conjunction with a thorough bibliographic review. Our findings indicate that from around 1124 records of algae in the Mediterranean Sea, only 114 species have been barcoded. We thus conclude that there are insufficient macroalgal genetic data from the Mediterranean and that this area would greatly benefit from studies involving DNA barcoding. Such research would contribute to resolving numerous questions about macroalgal systematics in the area and address queries related to biogeography, especially those concerned with non-indigenous species. It could also possibly result in the development and application of better, cost-effective biodiversity monitoring programmes emanating from UN conventions and EU Directives. One possible way of achieving this is to construct DNA libraries via sequencing and barcoding, subsequently enabling better cost-effective biodiversity monitoring through environmental DNA metabarcoding.
In this study we report the first finding of the red alga Acanthosiphonia echinata in the Mediterranean Sea. Specimens were identified using the DNA barcoding method and, in particular, the plastidial rbcL and the mitochondrial COI-5P markers. This species has been considered to be restricted to the western Atlantic and was reported in blooms from North Carolina to South Carolina. In 2015 the introduction of this species in Southeast Asia (Indonesia) was reported. Probably this taxon was introduced in the Mediterranean Sea from Indonesian populations associated with seaweed farming activities or hull fouling, via the western Atlantic-Mediterranean-Indonesia ship route.