International Journal of Farming and Allied Sciences Differential antioxidative responses of susceptible and resistant wheat cultivars against Fusarium head blight

ABSTRACT: Fusarium graminearum is an important disease globally that causes serious damages on crops particularly on wheat. Currently, the mechanisms underlying resistance to Fusarium head blight (FHB) are still unknown. To understand the host response to challenge by F.graminearum, we examined enzymatic activities in the wheat spikelet following inoculation with F.graminearum macroconidia. Greenhouse grown of two wheat cultivars Falat (susceptible) and Sumai3 (resistant) were inoculated by F.graminearum macronidia at the anthesis. Spikelets were harvested at 3, 5 and 7 days post inoculation (dpi). According to our results FHB infection in Sumi3 lead to significant increase of H2O2 and MDA contents as Falat but this induction was earlier in Sumi3. It seemed that increase in hydrogen peroxide in resistant genotypes was due to rapid induction of SOD (Superoxide dismutase) and decrease of CAT (Catalase) activity. Our results also indicated that POX (Peroxidase) and PPO (Polyphenol oxidase) activities were significantly increased in the resistant cultivar at 3 dpi, whereas increased activity of these enzymes was later in Falat at 5 and 7dpi. According to these results we suggest that rapid and more significant induction of antioxidative systems is the critical trait of wheat genotypes to resist FHB infection

Expression pattern of two sugar transporter genes (SuT4 and SuT5) under salt stress in wheat

Abstract Salinity stress is important abiotic factor, limiting wheat yield around the world and it is known to induce the accumulation of water soluble carbohydrates. These changes were accompanied by alteration in expression levels of a large number of carbohydrate metabolic genes. In present study, regulation of two wheat carbohydrate transporter genes, namely SuT4 and SuT5 during salinity stress at seedling stage were elucidates using quantitative RT-PCR. Salinity stress was induced using NaCl. Measurement on germination and seedling growth revealed Kavir as salt tolerant and Falat as salt susceptible cultivar. Expressions of two sugar transporter genes were differentially regulated during salt stress. Transcripts levels of both genes were almost higher in tolerant cultivar. Highest level of SuT4 and SuT5 transcripts was observed in -0.75 MPa of NaCl in salt tolerant cultivar. Transcript level of both genes down regulated in salt susceptible cultivar by increasing NaCl osmotic potential up to -1 MPa. Therefore, it seems that accumulation of sugars was necessarily correlated with accumulation of sugar transporter genes transcripts and salinity tolerance

The Effect of Salinity Stress on the Growth, quantity and quality of Essential oil of Lavender (Lavandula angustifulia Miller)

Introduction: Plants are usually exposed to different environmental stresses which limit their growth and productivity as well as cause considerable loss of worldwide agricultural production. One of the most important factors affecting plant and production of secondary metabolites is the salt stress. Salinity of soil or water is one of major stress, obstacles to increase production in plant growing areas throughout the world and especially in arid and semi-arid regions it can severely limit plant production. Iran is among the world's arid and semi-arid land, and faces water resources shortage and saline lands. According to the concept of sustainable development and role of Agriculture, using saline water and soil resources seems mandatory. Recently, medicinal and aromatic plants have received much attention in several fields such as agroalimentary, perfumes, pharmaceutical industries and natural cosmetic products. Although, secondary metabolites in the medicinal and aromatic plants were fundamentally produced by genetic processing, but, their biosynthesis are strongly influenced by environmental factors. It means that biotic and abiotic environmental factors affect growth parameter, essential oil yield and constituents. Abiotic environmental stresses, especially salinity and drought have the most effect on medicinal plant. Medicinal plants cultivation is one of ways to exploit these resources. Essential oils help to easier adapt to the environmental stress conditions. Also, essential oils are not constantly in the quantitative and qualitative terms. They are changing continuously, due to the requirements of the environment, and to individual survival. The different results were dedicated from the effect of salinity stress on the quantitative and qualitative parameters. Lavender (Lavandula angustifulia Miller) is a perennial woody medicinal plant that cultivated for its an essential oil in leafs and flowers. Major parts of Lavender produces essential oil are flowers and leaves. Materials and Methods: This experiment was carried out using a randomized complete block design with three replications to study the effect of salinity stress on growth parameters, essential oil constituents and yield of Lavender (Lavandula angustifulia) at the Horticultural Sciences Department, Plant Product faculty, Gorgan Agricultural Sciences and Natural Resources University. Lavender plants were obtained from seed plantation. The seeds in this investigation were obtained from the Institution of Forests and Range researches in Tehran. After three weeks stratification (4ºC) and germination, five plants were transplanted into similarized pots that were filled with perlite and cocopeat (2:1). Irrigation treatments with hydroponic solution were completed during germination until stage of 6-8 leaf. Then, five levels of salt stress, including 0, 25, 50, 75 and 100 mM NaCl levels were investigated during four months, applied in hydroponic. Length, shoot wet weight, root wet weight and root dry weight were measured at full flowering stage (after five months). The same time in order to evaluate percentage and composition essential oil, each plant were harvested and dried under room condition. After two weeks, Clevenger method was used to extract the essential oil from the plant foliage. The obtained essential oil were measured for calculating of essential oils percentage and then, analyzed by using GC/MS (Gas choromatography-mass spectrometry) for identification and quantification of the components. Statistical analysis of data was used with SAS software and charts preparing was done with Excel software. Mean comparison with LSD’s test in 5 percent probability was used. Results and Discussion: Results indicated that salinity stress motivated a significant influence in all of the growth parameters and essential oil yield and percent in P < 0.05. Increasing salt of the soil led to reduce in stem length, shoot wet weight, root wet weight and root dry weight and increase length of root and leaf essential oil percent at first, and then led to reduce these two parameters. The highest values of the essential oil percent were obtained from second level of salinity. Also, it was reported that salt stress had a significant effect on yield and percent of essential oil that was similar to our finding. This was reported that percent of essential oil in each plant and composition of essential oil changed. According to the results of this research, salinity treatment significantly increased essential oil percentage in Lavandula angustifulia. Conclusion: The most important of leaf essential oil component is Borneol that was increased. So, the medium level of salinity stress caused to increase in percent and quality of lavender essential oil

The RNA-seq transcriptomic analysis reveals genes mediating salt tolerance through rapid triggering of ion transporters in a mutant barley.

Considering the complex nature of salinity tolerance mechanisms, the use of isogenic lines or mutants possessing the same genetic background albeit different tolerance to salinity is a suitable method for reduction of analytical complexity to study these mechanisms. In the present study, whole transcriptome analysis was evaluated using RNA-seq method between a salt-tolerant mutant line "M4-73-30" and its wild-type "Zarjou" cultivar at seedling stage after six hours of exposure to salt stress (300 mM NaCl). Transcriptome sequencing yielded 20 million reads for each genotype. A total number of 7116 transcripts with differential expression were identified, 1586 and 1479 of which were obtained with significantly increased expression in the mutant and the wild-type, respectively. In addition, the families of WRKY, ERF, AP2/EREBP, NAC, CTR/DRE, AP2/ERF, MAD, MIKC, HSF, and bZIP were identified as the important transcription factors with specific expression in the mutant genotype. The RNA-seq results were confirmed at several time points using qRT-PCR for some important salt-responsive genes. In general, the results revealed that the mutant accumulated higher levels of sodium ion in the root and decreased its transfer to the shoot. Also, the mutant increased the amount of potassium ion leading to the maintenance a high ratio [K+]/[Na+] in the shoot compared to its wild-type via fast stomata closure and consequently transpiration reduction under the salt stress. Moreover, a reduction in photosynthesis and respiration was observed in the mutant, resulting in utilization of the stored energy and the carbon for maintaining the plant tissues, which is considered as a mechanism of salt tolerance in plants. Up-regulation of catalase, peroxidase, and ascorbate peroxidase genes has resulted in higher accumulation of H2O2 in the wild-type compared to the mutant. Therefore, the wild-type initiated rapid ROS signals which led to less oxidative scavenging in comparison with the mutant. The mutant increased expression in the ion transporters and the channels related to the salinity to maintain the ion homeostasis. In overall, the results demonstrated that the mutant responded better to the salt stress under both osmotic and ionic stress phases and lower damage was observed in the mutant compared to its wild-type under the salt stress

RNA-seq analysis and reconstruction of gene networks involved in response to salinity stress in quinoa (cv. Titicaca)

Abstract To better understand the mechanisms involved in salinity stress, the adaptability of quinoa cv. Titicaca—a halophytic plant—was investigated at the transcriptome level under saline and non-saline conditions. RNA-sequencing analysis of leaf tissue at the four-leaf stage by Illumina paired—end method was used to compare salt stress treatment (four days after stress at 13.8 dsm−1) and control. Among the obtained 30,846,354 transcripts sequenced, 30,303 differentially expressed genes from the control and stress treatment samples were identified, with 3363 genes expressed ≥ 2 and false discovery rate (FDR) of < 0.001. Six differential expression genes were then selected and qRT-PCR was used to confirm the RNA-seq results. Some of the genes (Include; CML39, CBSX5, TRX1, GRXC9, SnRKγ1 and BAG6) and signaling pathways discussed in this paper not been previously studied in quinoa. Genes with ≥ 2 were used to design the gene interaction network using Cytoscape software, and AgriGO software and STRING database were used for gene ontology. The results led to the identification of 14 key genes involved in salt stress. The most effective hub genes involved in salt tolerance were the heat shock protein gene family. The transcription factors that showed a significant increase in expression under stress conditions mainly belonged to the WRKY, bZIP and MYB families. Ontology analysis of salt stress-responsive genes and hub genes revealed that metabolic pathways, binding, cellular processes and cellular anatomical entity are among the most effective processes involved in salt stress