1Department of plants and crops, Ghent University, Belgium
2Department of Plant health, Estonian University of Life Sciences, Estonia
Potato late blight, a disease caused by the Oomycete Phytophthora infestans (Mont.) de Bary, is one of the most destructive plant diseases worldwide. The high cost as well as the environmental impact of fungicides-based strategies in combination with the rapid evolution within the P. Infestans population towards more virulent and more resistant patho types to fungicides is other crucial threats in potato production. Currently, used fungicides are not completely able to control the pathogen, thus environmentally friendly alternative control strategies need to be researched. Today, essential oils (EOs) can play an important role in addition to conventional fungicides to control plant pathogens. They represent a new class of crop protectants with such suitable effects like short shelf-life and low toxicity on the environment.
The aim of this study was to examine the anti-microbial activity of four pure Eos including; clove oil (Syzygiumaromaticum), juniper oil (Juniperuscommunis), tea tree oil (Melaleuca alternifoliai) and thyme (Thymus vulgaris) against P. Infestans mycelial growth as well as their effects on disease severity on potato leaves. The products were tested at five different concentrations (6.66, 3.33, 1.66, 0.83 and 0.41 µLmL−1) and compared to an untreated control. The efficacy of each EO was evaluated based on mycelia growth measured by colony diameters in amended media in three replicates. Also, the disease severity index (DSI) was assessed in a detached leaf essay after applying different EOs emulsions on the leaves of a susceptible potato cultivar (cv. Bentje). Results of the current study showed significant differences (P<0.05) for the different concentrations tested for each EO and between different EOs with different concentrations. Clove, tea tree and thyme EOs showed in vitro desirable inhibitory effect against P. Infestansmycelial growth, whereas clove and thyme EOs exhibited considerable protection against pathogen development on potato leaves. In addition, these two Eos showed no sign of toxic effects on potato leaves based on phytotoxicity assessments.
Keywords: Late blight, Phytophthora infestans, essential oils, phytotoxicity.
Neda Najdabbasi, is a joint PhD student between the department of plants and crops, Ghent University (UGent) in Belgium and the department of plants health, Estonian University of Life Science (EMU), in Estonia.
Her PhD research focuses on defense priming in potato plants against the pathogen Phytophthora infestans as an alternative biological control method. So, it encompasses wide range of experiments including pathogenicity tests, measuring volatile profile of potato plants based on GC_MS analyses and characterization of defense genes expressed. Besides, some other alternative priming methods such as using antagonists, essential oils, plant extracts and potassium phosphate against P. infestans will be investigated.
University of Science and Technology-Mohamed Boudiaf, Algeria
Context: Pathogenic bacteria cause many plant diseases; the severity of which can be mitigated by the associated non-pathogenic bacteria. The control of plant pathogens using biological control is more advantageous for the environment compared to chemical control.
The objective of this work is to investigate the in vitro antagonist effects of Methylobacterium sp against Pseudomonas savastanoi, the causative agent of tuberculosis in the olive tree.
Methods: Isolation and pre-identification of Pseudomonas savastanoi from an olive-infected tree (Oleaeuropaea L.), according to the EPPO (European and Mediterranean Plant Protection Organization) protocol.
The study of the antibacterial activity of Methylobacterium sp and Pseudomonas Savastanoi using the direct method of Fleming and al. (1975) and the indirect method of Barefoot and Klaenhammer (1983).
Results: The study of the in vitro antibacterial activity against Pseudomonas Savastanoi using the indirect method has shown a greater inhibitory activity than that of the direct method and the realization of a suitable indirect method allows us to suggest that the metabolites inhibiting the P savastanoi secreted by Methylobacterium sp are intracellular.
Conclusion: Biological control tests using Methylobacterium sp, to limit the incidence of P. savastanoi, are study worthy. These non-negligible antagonistic effects could join other methods of control, such aschemical or genetic.
Keywords: Methylobacterium sp, Pseudomonas savastanoi, olive, biological control.
Nature Research Centre, Institute of Botany, Lithuania
Goal–to investigate the impact of ProbioHumus and Humate Gel A Gon photosynthetic productivity of oat. The small-plot trials was conducted in the period between 2016–2017 at the Field Experimental Station of the Nature Research Centre in soil Calc(ar)i-Epihypogleyic Luvisol. Commercial ProbioHumus, “Baltic Probiotics” and Humate Gel AG “Hydro Thermo Dynamic Technology”, Latvia, were used. ProbioHumus and Humate Gel AG composition content are microbiological bacteria. The object of investigation was oat. Physiological investigations of chlorophyll and carotenoid content in the leaves of oat cultivar were carried out at the outset of the leaves. The dependence of chlorophyll and carotenoid content on the ProbioHumus and Humate Gel AG variant was established at that time. The content of chlorophyll (a, b), (a+b) was measured and carotenoid content was determined on each variant. Chlorophylls a/b ratios and amounts of chlorophylls (a, b), carotenoids were calculated according to Wellburn (1994). The results indicated that chlorophyll and carotenoid content in oat leaves depended on ProbioHumusin the substrate and spread oats leaves with preparation Humate Gel AG. This was demonstrated by the variant with probiotics soil, where chlorophyll and carotenoid content in oat plants was the highest. The variant of ProbioHumus (the content of chl a−12%; chl b – 13%, carotenoid –9%, compared to the control) turned out to be most favourable. The next –Humate Gel AG (chl a–10%; chl b–10%, carotenoid –9%) and the variant with ProbioHumus+Humate Gel AG (chl a– 12%; chl b– 11%, carotenoid –8%). Grain yield of oat in treated plots tended to increase and in the plots, treated with ProbioHumusa significant increase in grain yield was obtained. There was found relationship between grain yield of oat and chlorophyll a, b amount and chlorophyll a+b. Weak but significant correlation was identified between the amount of chlorophyll a, b.
Lina Pakalniskyte is a research fellow of Nature Research Centre of Institute of Botany of Laboratory of Plant Physiology (of 1997). She started PhD studies in 2016. The topic of the dissertation is “Research of plant physiological responses to enzymatic compositions of probiotics”. The objective of work: to investigate the effects of fermented probiotics on agricultural crop growth, development, yield quality and soil structure formation. She has published 20 papers in reputed journals.
Institute of Fisheries and Marine Sciences (IH.SM), University of Toliara, Madagascar
In Madagascar, Shrimps exploitation generates, by the shelling, a lot of wastes. 60% of the shrimp is rejected as garbage, yet they contain biomolecules of biotechnological interest, which are able to influence the physiology of organisms. Therefore, a study has been realised from November 2016 to January 2017, the goal is to propose a way of valorisation of shrimpʼs wastes in aquaculture notably in Oreochromis niloticus nutrition.
The experience was done in the Marine Resources Valorisation laboratory (VALOREMAR) of IH.SM, the properties of shrimpʼs heads was increased by autolysis, which uses the endogenous pepsin of the viscera. Once wastes was mached, melt and homogenized, the reaction is started with activation of the pepsin at pH = 2 and 40 °C. Those parameters of hydrolysis (pH, temperature and hydrolysis degree) are controlled by the methods of pH-stat. The reaction is stopped after two hours by thermal inactivation of the enzyme. The autolysate powder is obtained by drying (at 70 °C) and grinding the supernatant obtained after centrifugation.
For the test of efficiency in fish nutrition, three experimental rations are tested respectively on three replicate lots of Oreochromis niloticusʼs (Tilapia) juveniles. The protein source from animal is brought by the fish meal in the witness feed and is replaced, by the autolysate, partially in the food A50 (50%) and totally in the food A100 (100%). Juveniles were fed twice a day under the same conditions. The zootechnical performances are followed weekly for 6 weeks and were compared by the one-way ANOVA test on Systat 12 at a significance level of 5%.
An average degree of hydrolysis of 35.63 ± 1.49% and an autolysate yield of 8.21 ± 2.49% were recorded. The kinetics of hydrolysis presents the phase of fast growing and latency. After six weeks, the tested lots show higher performances compared to the pilot, especially those that are fed with food A100. The average gains of weight and height are respectively 35, 48 ± 13, 21g/10, 34 ± 1, 19cm for lot A100 and 32, 17 ± 10, 8 g/9, 98 ± 1, 37cm for lot A50 against 28, 50 ±7, 76 g/9, 38 ± 1, 22 for the pilot.
In conclusion, shrimp wastes constitute accessible resources of biomolecules valorizable by biochemical processes like autolysis. This process increases their functional and nutritional properties. Those products transfer into the fish feed increases the digestibility and growth of fish while decreasing the duration and costs of aquaculture.
Razanajaosoa Marie Celina, is a Student in Marine biotechnology at “Institute Halieutiques et des Sciences Marines”, University of Toliara (Madagascar), also treasurer at Young researchers Organization (YSO-Madagascar). She learnt marine biology and biotechnology, including the diversity of biomolecules and its potential in biochemistry. Her experience in biotechnology begun with my research on the “Valorization of shrimpʼs heads (Penaeus sp.) by enzymatic hydrolysis in fish nutrition” for the obtention of her bachelor degree in 2017 in the Valoremar (Marine Resources Valorizations) laboratory of the IH.SM. Then, she was included to the laboratoryʼs equip of researchers, where she mentoring laboratoryʼs work for Master Class. Since she was in school, her passion is to discover the power of marine diversity on human health and her focus is improving Marine pharmacology in her country. She actually prepare her research on ascidian species with therapeutic potential in southwestern Madagascar and their biological activities.
Thermal Processes Laboratory-Center of Energy Research and Technologies, Tunisia
Greenhouse heating during cold seasons is costly as it is high energy-consuming. The use of latent heat stored during sunny periods for greenhouse heating could be an interesting alternative in several regions worldwide as in Tunisia. Thus, new agronomic/climatic approaches were developed to produce several crops such as tomato in a sustainable way. In this context, maturity and yield of tomatoes cultivated inside a greenhouse equipped with a new solar air collector with latent storage (IGHLS) were studied in comparison to an unheated greenhouse (IG). Using the solar collector, the night recovered heat reached 29% of total heating requirements. Consequently, IGHLS microclimatic conditions positively affected maturity and led to an early fructification and an increased yield as compared to the unheated greenhouse. The solar collector revealed to be an efficient competitive system enhancing early maturity, leading to increased tomato yields and reducing considerably greenhouse heating costs as it utilizes a highly solicited natural renewable energy.
Sellami Douja is a Technician in the Laboratory of Thermal Processes at the Energy Research and Technology Center of Tunisia. She is a doctoral student. She does her research in the same working laboratory in collaboration with another biotechnology laboratory.