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.

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 β-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.

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 syringae pv. tomato (Pst) strain DC3000. Also, the activities of defense response genes WRKY70 and CaBP22 in Arabidopsis thaliana under propolis application were compared. 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.

Many stressors contribute to productivity and quality losses in agricultural production, ranging from the rising global population to shrinking agricultural lands. To boost yield and quality, plants must be protected from abiotic and biotic stressors. Seed priming is the process of boosting germination and seedling development by treating seeds with particular pre-treatments before germination. Seed priming is used to improve plant yield and germination. Plant defense elicitors stimulate the plant’s natural immune system when administered externally, strengthening the plant and making it more resistant/tolerant to diseases. β-Aminobutyric Acid (BABA) is a plant defense elicitor, and in this study, the effect of BABA seed priming on Clavibacter michiganensis ssp. michiganensis (Cmm), which causes bacterial cancer in tomato (Solanum lycopersicum L.), was investigated. Tomato seeds were subjected to seed priming for 72 h with 12 mM BABA (BABA priming) or water (water priming) as the control group. Tomato seedlings that germinated normally were utilized as a positive control. When the plants reached the 3–4 leaf stage, they were infected with Cmm. According to the data, BABA priming was the most effective experimental group in reducing disease severity. Furthermore, it has been shown that the use of BABA as a spray or water-priming application gives better protection than the control treatment. To understand the molecular basis of this suppression, plant samples were obtained at two separate time points (0th and the 7th day), and transcriptional changes of essential plant immunity genes (NPR1, PAL, PR1, WRKY70, WRKY33b, TPK1b, and PR5) were studied. The qRT-PCR results showed that NPR1 gene expression increased considerably with the BABA priming treatment compared to the control. BABA priming at the 0th hour enhanced NPR1 gene expression by approximately five times. In addition, BABA priming increased PR1 gene expression. Furthermore, foliar spraying of BABA (BABA priming+BABA-Sp) on seed-primed plants resulted in a nine-fold increase in PR1 gene expression. At day 7, the BABA priming+Cmm treatment increased PR5 gene expression. Along with the control of other genes, the molecular architecture of BABA seed priming has been attempted to be discovered. The application of BABA seed priming is expected to contribute to the literature and have favorable impacts on plant protection against Cmm.

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 ssp. arvense L.) 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.