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    Alleviation of Salt Stress with Chitosan Foliar Application and Its Effects on Growth and Development in Tomato (Solanum lycopersicum L.)
    (2022) Özkurt, Nazlı; Bektaş, Yasemin
    Environmental and climatic fluctuations as well as abiotic stress factors affect agricultural production and cause a loss in quality and yield. It is important to find alternative solutions for the sustainability of agricultural production to feed the increasing population. Salt stress is one of the most devastating abiotic stress factors and tomato (Solanum lycopersicum L.) production is also affected by salt stress since it needs extensive irrigation for high yield. The exogenous application of some plant inducers showed promising results in the induction and improvement of plant tolerance to stress factors. Chitosan (2-amino-2-deoxy-b-D-glucosamine), one of the organic compounds, is getting significant attention in agriculture with its potential. Here, we evaluated the potential of chitosan application for salt stress tolerance on tomato. 0.03% and 0.05% chitosan solutions were applied as a foliar spray to the plant and salt tolerance improvement were investigated under untreated (0 mM NaCl) and 100 mM NaCl conditions. The growth-related (root and shoot diameters, above and below-ground biomass, number of leaves and branches, and plant height), photosynthetic parameters (chlorophyll a, b, total carotenoid content), and ion leakage were investigated. According to the results, chitosan application improves plant development in both untreated and salt-stress conditions and improved plant growth. Also, photosynthetic parameters showed that the application of chitosan increased chlorophyll contents under untreated conditions. Our result suggests that the application of chitosan may have a promising effect on salt stress tolerance and further research may shed light on its molecular mechanisms.
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    Chemical Priming with ?-aminobutyric acid (BABA) for Seedling Vigor in Wheat (Triticum aestivum L.)
    (2022) Özkurt, Nazlı; Bektaş, Yasemin
    To achieve efficiency in seedling development, the seed must germinate quickly and homogeneously. Pre-sowing applications such as priming are practiced to eliminate or reduce the negative effects of environmental factors through germination and seedling development. This allows to reach a higher germination rate, yield, and desired plant density, especially by protecting against biotic and abiotic stresses. This study was carried out to examine the effects of pre-sowing seed applications on seedling growth and vigor of bread wheat (Triticum aestivum L.). Three different doses of ?-amino-n-butyric acid (BABA) were used as seed priming agents and Dimethyl sulfoxide (DMSO) as control groups. The study was carried out according to the completely randomized factorial design with three replications and ten plants per replication. As a result of priming applications, significantly higher values in the number of roots, longest root length, total root length, average root length and shoot fresh weight were obtained compared to control. Our results, for the first time, showed that seed priming with BABA had a promoting effect on many aspects of early seedling growth in bread wheat. This is a preliminary study to understand the mechanism of seed priming and its effects on germination and root growth in wheat. Further studies may shed light on the molecular mechanisms of BABA or other compounds as seed priming agents, benefits for abiotic and biotic stress tolerance, and good stand establishment at the seedling or later stages.
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    Comparative evaluation of salicylic acid (SA) and 2,4-dichloro-6-{(E)-[(3methoxyphenyl)imino]methyl} phenol (DPMP) on growth and salt stress tolerance in forage pea (Pisum sativum L. arvense)
    (2022) Özkurt, Nazlı; Bektaş, Yasemin
    Alleviation of salt stress is becoming one of the urgent needs of agricultural production. Even though enhancement of tolerance levels with genetic variation is a common approach, exogenous applications of various compounds are a newly emerging field. Here, the effects of two different plant elicitors, salicylic acid (SA) and 2,4-dichloro-6-{(E)-[(3methoxyphenyl)imino]methyl} phenol (DPMP) on growth and stress tolerance levels of forage pea (Pisum sativum L. arvense) were evaluated. Plants were exposed to salt stress (100 mM) in addition to DPMP, SA, or DMSO (Solvent) foliar spraying. The results revealed contrasting effects for each elicitor. Under non-stressed conditions, DPMP applied plants had higher values in plant height, shoot dry weight (SDW), and taproot length, while SA applied plants had significantly higher shoot fresh weight (SFW), and DMSO applied plants had higher values in root fresh (RFW) and dry (RDW) weights, and root/shoot ratios. When we evaluated stress tolerance index (STI) levels, DPMP applied plants had higher STI values in SFW, SDW, RFW, and RDW. DPMP improved STI and biomass allocation better than SA and DMSO. These elicitors may have significant potential in abiotic stress tolerance, in addition to their well-known biotic stress eliciting roles. There is a need for further research to define appropriate doses and application times.
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    Comparative Evaluation of Two Commercial Propolis Extracts as Plant Defense Activator and Antimicrobial Agent Against Pseudomonas syringae pv. tomato (Pst) strainDC3000
    (2021) Ateş, Melda; Özkurt, Nazlı; Bektaş, Yasemin
    Propolis is a natural bee product that protects the beehives from internal and external factors. It is a natural-complex compound with a wide potential use as an antimicrobial, anti-fungal, and anti-inflammatory effect. The role of propolis as a plant protection agent and an alternative to pesticides is an unexplored area. Here, two different commercially available propolis extracts were evaluated for antibacterial effects on Pseudomonas syringaepv. tomato (Pst) strain DC3000. Also, the activities of defense response genes WRKY70 and CaBP22 in Arabidopsis thaliana under propolis application werecompared. According to the results, each propolis extract and dose had a different effect on gene expressions as well as antibacterial activity. One of the commercial brands had a significant effect at all doses while another brand’s propolis extract had its activity at only 1% concentration. Propolis reduced bacterial growth up to 93% with a 2% concentration. For the first time, propolis is also evaluated for its capacity as a plant defense activator agent and it induced WRKY70 and CaBP22 gene expression. The differences in gene expression and bacterial growth inhibition levels suggest the importance of the origins of propolis, such as plant species and regions it collected. While preliminary in nature, these results suggest a significant potential of propolis in plant protection in commercial and organic agriculture.
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    Plant defense elicitor, 2, 4-dichloro-6-{(E)-[(3-methoxyphenyl) imino] methyl} phenol (DPMP) and its mode of action against fungal pathogen Alternaria solani in tomato (Solanum lycopersicum L.)
    (2022) Kaba, Adem; Bektaş, Yasemin
    Biotic stress factors are one of the major constraints plants face, and they significantly affect production and yield. There are multiple ways to cope with stress factors, including genetic enhancement. When they cannot provide sufficient protection, pesticides are commonly applied. Plant defense elicitors are a new approach for boosting plants' natural immune responses and tolerance levels. The newly identified promising plant defense elicitor; 2, 4-dichloro-6-{(E)-[(3-methoxyphenyl) imino] methyl} phenol (DPMP) was previously studied against the oomycete Hyaloperonospora arabidopsidis, the bacterial pathogens Pseudomonas syringae and Clavibacter michiganensis ssp michiganensis and found to induce disease resistance against these phytopathogens. However, it was not tested against fungal pathogens. Here for the first time, DPMP was evaluated against one of the most destructive fungal pathogens, Alternaria solani. Disease severity and plant development were evaluated. The results revealed that DPMP neither inhibited nor enhanced the disease severity of A. solani. Gene expression of several salicylic acid, jasmonic acid, and ethylene pathway-related genes (Pti4, TPK1b, Pto kinase, PRB1 2, SABP2, and PR3) were also analyzed. According to the results, while DPMP induces PRB1-2, TPK1b, and Pto kinase gene expressions, the protection against A. solani does not occur via these genes. PR3 is one of the most important genes for defense responses against necrotrophic pathogens, and DPMP downregulated gene expression of PR3. These results demonstrated that DPMP mostly takes a role through the SA-related defense pathway and was effective against biotrophic and hemibiotrophic pathogens. However, it is not suitable for protection against the necrotrophic pathogen A. solani. Further research may pinpoint the activity of DPMP on the defense pathway and provide a better understanding of the mode of action for DPMP and other plant elicitors for specific plant protection solutions.
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    The Effect of Plant Growth Promoting Rhizobacteria on Root Growth in Bread Wheat (Triticum aestivum L.)
    (2021) Bektaş, Harun; İnal, Behçet; Sonkurt, Mehmet; Çığ, Fatih; Bektaş, Yasemin
    Bread wheat (Triticum aestivum L.) is the most produced cool-season cereal in the worldand meets about 20% of our daily caloric intake. Climate change negatively affects grain yield, it is,therefore, necessary to improve climate-resilient wheat crops. It is a known fact that subsoil parametersare not mostly included in the breeding selection criteria due to some technical limitations. For thisreason, it is essential to examine the root system, which has a fundamental role in drought tolerance,for morphological, anatomical, physiological, and architectural aspects, to understand the geneticmechanisms of these traits and to determine breeding strategies. In this study, the seeds of twodifferent bread wheat varieties were inoculated by three different plant growth-promotingrhizobacteria (PGPR), which synthesize the ACC deaminase enzyme. When the results were evaluated,significant differences were observed between varieties and bacterial applications for the total rootlength and root growth angle. As a result of the study, it was observed that all three bacteria specieshad a positive effect on root development. Brevibacillus choshinensis was the most effectiveinoculation on total root length in Gerek 79 (95.4 cm), while it was Arthrobacter agilis in Bezostaja 1(62.8 cm). We suggest that plant growth-promoting rhizobacteria have a positive effect on wheat rootdevelopment and a detailed analysis of this effect should be carried out with future studies.
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    Variation of Some Plant Growth Parameters in Coriander (Coriandrum sativum L.) with Copper Application
    (2021) Özyazıcı, Gülen; Bektaş, Yasemin
    This study was carried out to investigate the effect of different copper (Cu) concentrations on some plant growth parameters in coriander (Coriandrum sativum L.). The study was perfomed at the Agricultural Biotechnology growth room, Faculty of Agriculture, Siirt University (Turkey). In the study, the coriander Mardin province population was used as plant material. Five different doses of Cu (0, 100, 200, 300, and 400 ppm) were applied to plants. Plant height (cm), stem diameter (mm), the number of branches per plant, the number of umbel per plant, the number of seeds in the main umbel, plant fresh, and dry weights (g) were determined. According to the results, the effect of different Cu concentrations in all growth parameters except stem diameter and number of branches were found to be significant. In the current study, plant height, stem diameter, number of branches, number of umbel, number of seeds in the main umbel, and plant fresh weight and dry weights were ranged between 41.31-52.79 cm, 1.57-2.18 mm, 3.07-5.71 per plant, 2.57-4.86 per plant, 13.36-37.86 per plant, 2.33- 4.12 g and 0.239-0.550 g, respectively. In the study, it was concluded that coriander can be included in phytoremediation programs in Cu-contaminated areas