Journal of Plant Molecular Breeding
Volume:8 Issue: 2, Summer and Autumn 2020

Shikonin is a naphthoquinone with some important medicinal properties and is found in gromwell plant. There are so many biotechnological approaches proposed for the productivity enhancement, and elicitation is recognized as one of the most effective strategies for increasing the production of secondary metabolites in plant in vitro cultures. Moreover, a deeper understanding of the mechanisms and factors affecting shikonin biosynthesis can led to the design of more intelligent and efficient biological production systems. To this aim, in the present study, the expression of some genes related to the shikonin biosynthetic pathway including PAL, 4CL, HMGR, GPPS and PGT in in vitro cultures of Lithospermum officinale in response to methyl jasmonate (MJ) at different times, were investigated by real-time PCR. The results showed that MJ had a significant effect on increasing gene expression levels in elicited samples compared to control samples. Additionally, we found that the studied genes respond to MJ with different pattern, in which the highest increase in gene expression level was observed for PGT while the lowest increase was observed for GPPS. Maximum and minimum transcript levels were obtained in most genes at 4 and 96 h post-elicitation, respectively. It was also found that phenylpropanoid pathway genes respond better to MJ than terpenoid pathway genes. The results of the present study would increase our knowledge about elicitor signal transduction pathways, and may be particularly useful for enhancement of shikonin production in plant cell cultures of L. officinale.

Salinity is one of the most important non-biological stresses that affect plant growth and development. Effect of different levels of NaCl (0, 2, 4, 6 and 8 dS/m) were investigated on enzymatic and non-enzymatic activities in C64 and C68 oilseed sunflower genotypes at two times; 3 and 12 days after salinity stress application. Net photosynthesis rate, chlorophyll content and soluble proteins amount decreased by increasing salinity level but proline and malondialdehyde (MDA) contents increased. However, the changes in net photosynthesis in the two studied genotypes was different across time and do not follow statistically the same trend line. In genotype C86, the reduction of photosynthesis rate at all studied salinity levels was very high compared to normal condition (0 dS/m) after 3 days; especially at salinity levels of 2, 4 and 6 dS/m, while 12 days later, the decrease of photosynthesis rate was moderate at salinity levels of 2 and 4 dS/m but severe at 6 and 8 dS/m salinity levels. The highest amount of proline (31.36%) related to tolerant genotype and the lowest amount (7.72%) related to susceptible one was measured 12 days after 2 dS/m salt stress treatment. Considerable MDA was observed in both tolerant and sensitive genotypes 12 days post salt stress application; the highest amount (83%) was observed at 8 dS/m treatment. Catalase and ascorbate peroxidase activity increased with increasing salt intensity. The rate of increase in guaiacol peroxidase activity was higher in C86 genotype than C64. Chlorophyll a and total chlorophyll contents decreased in both sunflower genotypes under salinity stress. The lowest amount of total chlorophyll (8.6%) was observed in the salinity level of 8 dS/m in the sensitive line (C64). Results revealed the C64 and C68 selected genotypes from two our identified sunflower heterotic groups have different physiological response to salinity stress and C68 is more tolerant to salt stress than C64. So, they can be potentially used as parents in sunflower breeding programs to produce salt stress tolerant hybrids.

The present study has been designed and executed to determine the best growth-regulating compound for callus induction as well as to specify the optimum dose of gamma irradiation in carnation cultivars (Tabasco, Nobless, Cameron, Tabor, Eskimo, and Mariposa). In this experiment, an MS culture medium was used to evaluate the various levels of growth regulator concentrations including NAA in four levels (0, 0.5, 1, and 2 mgl-1), 2,4-D in five levels (0, 0.5, 1, 2, and 3 mgl-1), and BA in two levels (0.5 and 1 mgl-1). Irradiating the callus of leaf explants was carried out three weeks after cultivation at 0, 15, 25, 35, 45, and 55-gray doses-to determine the optimum dose of gamma radiation. The analysis of data and illustration of graphs were carried out via Excel software and according to the obtained results, the radiation level that killed 50% of the calluses was selected as the optimum dose for further experiments. The results have indicated that all main effects and the interaction effects regarding the characteristics of callogenesis percentage and callus volume were significant at a probability level of 1%. Means were grouped using Duncan's multiple range test, revealing that the highest level of callus induction was in Eskimo cultivar with a 73% overall mean. Overall, the results indicate that 2 mgl-1 2,4-D, 0.5 mgl-1 BA is the best regulatory compound for callogenesis in carnation cultivars. Moreover, it was found that on average, the 25-gray dose leads to suitable results in the callus explants of all cultivars.

Under global warmth conditions, it is expected that tomato yield will reduce due to insect pests and fungal diseases such as fusarium wilt. Using of biological control agents is effective in the control of both groups as regard as an ecofriendly and economically rational practice. Here, Bacillus thuringiensis (Bt) was used to study its capability to prime tomato resistance against fusarium wilt caused by the fungus Fusarium oxysporum f. sp. lycopersici (Fol). Priming of tomato cv. Falat C.H. seedlings was performed at 4-5 leaf stage and leaf samples were analyzed 3, 18, 24, 48 and 72 hours after fungal treatment (hat). The rate of hydrogen peroxide (H2O2) and changes in the relative transcription of the antioxidant enzyme genes such as superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were evaluated using qRT-PCR. No significant change was observed in the relative transcription of the CAT gene. The relative transcription of SOD, and GST genes was increased with time in the treated plants compared to control plants. The highest rate of relative transcription of SOD was found at 18 and 24 hat, and for GST at 18 and 72 hat. The increment of genes transcripts was in agreement with the reduced level of H2O2 in Bt-primed plants. These results are in accordance with the effectiveness of Bt in the induction of tomato systemic resistance to the F. oxysporum f. sp. lycopersici.

The main source of protein and micronutrients in wheat grains is the flag leaf and to a lesser extent the lower leaves. As healthy leaves reach the final stage of growth, senescence, they remobilize the nutrients necessary before tissue destruction and death. This experiment was carried out in Golestan province, and the Wheat cultivars studied were included Euclide and Antonius. Sampling was carried out from flag leaf, other leaves, stem, and grain at 7 stages, Anthesis, 7, 11, 15, 19, 23, and 27 Day After Anthesis (DAA). The total chlorophyll content in the Antonius cultivar was higher in both flag leaf and other leaves than Euclide cultivar. The expression of TaNAM-B1 and TaSAG12 genes, which have been identified as signaling genes for senescence in wheat, showed results consistent with the results of chlorophyll content in leaves. Increased expression of both genes after anthesis was observed earlier in Euclide cultivar than the Antonius cultivar and had higher expression in most stages. In light of the results, the change in concentrations of Cu, Zn, and Fe in the Euclid cultivar was more in all organs than in Antonius one. Also, given the importance of minerals in the food basket, it can be noted that Euclid cultivar, in which leaf senescence begins earlier and more minerals are stored, can produce grains with higher nutritional value than Antonius cultivar.

Sesame (Sesamum indicum L.) seed is a rich source of oil and protein, which could be used for cooking or primary source for some industrial applications. Seed germination is the most fundamental stage of a plant’s life cycle, which is significantly influenced by various abiotic stresses. As a first report, the study attempted to evaluate the effect of environmental factors (i.e., low, optimum and high temperatures (T), water potential (ψ) and salinity) on eight superoxide dismutase (SOD) gene expressions (two Mn-SOD, two Cu/Zn-SOD and four Fe-SOD) during sesame germination. Results showed that all studied treatments remarkably influenced germination characteristics of sesame (P ≤ 0.05). In general, the negative impact of each stress on sesame germination could be ranked as ψ > salt stress > high T > low T, indicating that the germination was more influenced by ψ than salt stress and T. There was a strong association between the decrease in germination parameters (relative to the optimal T) and the decrease in SiSOD expression under various stresses. Our results discovered that the SiSODs expression patterns were stress-specific. However, when subjected to the same stress, the majority of SiSOD genes displayed similar expression patterns. The findings of this study could lead to a better understanding of SOD's role in other plants and the mechanisms involved in plants' stress responses, especially during their early stages of development.

Arbuscular mycorrhizal fungi (AMF) symbiosis could mitigate the adverse effects of abiotic stresses in various plants. The aim of this study was to investigate the effect of AMF-inoculation on expression of several stress-responsive genes in two rice cultivars under different water conditions. The seedlings of Tarom-Hashemi and Nemat rice cultivars were transplanted in soil with or without G. mosseae spores. At the tilling stage, the AMF-inoculated (+AMF) and AMF-uninoculated (−AMF) plants were subjected to flooded and water deficit conditions (70% field capacity (FC) and 50%FC). The genes expression was evaluated by qRT-PCR and reported relative to control (flooded, -AMF) plants. The results showed lower expression of osDREB2A in +AMF plants in comparison with –AMF plants under water deficient conditions. The expression of OsPIP1;2 was significantly increased in roots of +AMF to –AMF plants. But, the expression of this gene was decreased in shoots of +AMF and –AMF plants in comparison with control plants. The stress-responsive gene transcripts, OsPIP2;3, OsGH3-8, OsLTP, OsAOS2 and OsADC1 in +AMF rice cultivars was higher than -AMF plants at both water deficit conditions. Expression of OsP5CS in +AMF and –AMF plants was increased in comparison with control plants, though, their differences was not significant. In 70%FC, OsEXP15 gene expression of +AMF and –AMF root plants was increased in comparison with control plants. However, under 50%FC the gene expression was decreased and not changed in -AMF and +AMF plants, respectively. It seems AMF induced changes in rice genes expression may enhance tolerance to water deficit conditions.