Journal of Plant Molecular Breeding
Volume:10 Issue: 1, Winter and Spring 2022

A few small molecular weight signals, including jasmonic acid (JA), salicylic acid (SA), and ethylene (ET), regulate the expression of defense-related genes in plants. These signals serve to inhibit the activation of plant defense genes against aggressors and can manipulate the plant's defense signaling pathways. In this study, the impact of acetosyringone on the induction of virulence genes was examined in Agrobacterium tumefaciens A348 (MX311) and A348 (MX243) at three different levels: 0, 100, and 200 μM. The concentration that demonstrated the highest induction of virulence genes was then used for transforming Arabidopsis mutants using A. tumefaciens EHA105, with the aim of inducing virulence genes. Results revealed that virD2 expression reached its peak at 200 μM acetosyringone, while virB2 expression was highest at 0 μM. Additionally, transformation experiments indicated that the SA mutants (nahG) exhibited the highest transformation efficiency, while the control plants (Col-0) displayed the lowest efficiency. Therefore, the efficiency of gene transfer in SA-suppression mutants suggests a more significant role for SA in plant defense against pathogens compared to the other hormones. Enhancing gene transfer efficiency in these mutants could unlock the potential for increased expression and production of recombinant proteins compared to the wild type.

In the context of the increasing demand for cultivation of marginal lands affected by salinity, it became necessary to assess the most important crop traits that can be relied upon as well as to identify genotypes that have the potential to withstand adverse environmental conditions. In this study, ten genotypes of safflower were evaluated under two salinity levels during two successive agricultural seasons. According to correlation and path coefficient analysis and positive direct effect of studied traits, 100 seed weight followed by number of capitulum per plant strongly related to seed yield. Also, the results confirmed based on tolerance indices to salt stress, that line 6 was followed by local cultivar recorded the highest values as an indicator of tolerance. Protein analyses were conducted to identify protein markers associated with salinity tolerance for selection of promising lines tolerant to salt stress. This investigation revealed substantial polymorphism in protein markers that could be useful tools to assist breeders in the selecting and breeding of safflower lines tolerant to salinity stress.

MicroRNAs are small RNAs known for their essential roles in regulating both biotic and abiotic stress responses. Drought stress poses a significant challenge to wheat productivity in Iran. The present study evaluated the expression of miR9863a and its target genes in wheat, as well as three Aegilops species under drought stress. The results revealed differential expression of miR9863a in the shoots of the studied plants under drought stress conditions. Specifically its expression was increased in Ae. tauschii and Ae. crassa, while decreasing in Ae. cylindrica. The observed differential expression could be explained by the inherent nature of miRNA as a mediator molecule in various biological processes. Analyzing the expression pattern of miR9863a and its target genes in Ae. tauschii suggests that the effect of miR9863a in response to drought stress may be attributed to PLGG1, impacting glycerate/glycolate transfers and SAR1A,  influencing trafficking of transcription factors from the endoplasmic reticulum to the nucleus. In addition to complementing previous studies on the role of miR9863 in countering plant diseases, the results presented here  illustrate how this miRNA assists the abiotic stress-response mechanism in plants, particularly in the context of drought stress.

The comet assay is a sensitive test for detecting DNA damages used as an instrument to compare the intensity of the genotoxic effects of colchicine. The Pattern and the index value of three parameters of comet assay (tail length, tail intensity, tail moment) were compared among the autotetraploids produced from three populations of diploid cross pollinated Medicago sativa spp. Caerulea and autotetraploid populations from five diploid self pollinated species by treatment with three concentrations of colchicine (0.1, 0.5, and 1%) and five alfalfa cultivars. Results have shown the same level of increases and pattern in the parameters of comet "among the induced tetraploids from the two categories of medics" in the concentration of 0.1 and 0.5% of colchicine. Also increasing colchicine concentration from 0.1 to 0.5% resulted in a more pronounced augmentation of comet parameters. Induced tetraploids resulted from the two mentioned colchicine concentrations showed increases in the value of the three comet parameters compared to the cultivated alfalfa cultivars and two diploid categories medic species so the pattern of parameters were not similar. At the concentration of 1% of colchicine, only two annual species produced tetraploids showing very pronounced augmentation of comet parameters in comparison with 0.1 and 0.5% colchicine concentrations. Changes in patterns and values of the three parameters in induced tetraploids compared to cultivated alfalfa and diploid medic species demonstrate differential effects of damages of colchicine from one concentration to another, then a new variability in each concentration change will be created.

The WRKY transcription factors (TFs) family is one of the largest plant-specific TFs families that play a key role in mediating pathways of stress response. In current study, an overview analysis was performed on Arabidopsis WRKY TF family members that their differential expression (DE) under various stresses was reported in GEOprofile database. First, WRKY members with DE were extracted from GEOprofile and information of the data set, sequence and their gene structure were obtained. Then, the concept of the intersection of sets was used to selection some of WRKY TFs for downstream analysis. DE of candidate members was compared by t-test. The protein – protein interaction network were predicted by STRING web server. A total of 16 WRKY genes were identified in the 11 dataset of GEOprofile. The sequence information showed that WRKY75 and WRKY33 have the minimum and maximum length of the amino acid sequence, respectively. Analysis of the gene structure showed that 56% of the studied WRKY genes have 3 exons and all 16 members are distributed in all five chromosomes of Arabidopsis. Also, the results showed that four WRKYs including WRKY40, WRKY46, WRKY18 and WRKY33 were most frequent at response to various stresses. The protein-protein interaction network showed that WRKY40, WRKY46, WRKY18 and WRKY70 have high interaction with four genes of MPK4, ACS6, MKS1 and STZ. Therefore, WRKY40, WRKY46, WRKY18 and WRKY33 can be the most important WRKY TFs of Arabidopsis at response to various stresses and can be used in genetic and metabolic engineering projects.

Drought stress is one of the most important factors limiting the growth and production of crops. Exogenous application of some biological or chemical agents can mitigate the negative effects of drought stress. In this experiment, the effect of hydrogen peroxide application on water-stressed corn plants was investigated through various biochemical and molecular methods. Corn seedlings grown in hydroponic culture were treated with hydrogen peroxide (2 mM) and then exposed to water stress using polyethylene glycol 6000 at 3 levels of 0, -2 bar and -4 bar. The results showed that drought stress altered all of the studied traits significantly. With increase in stress level, the activity of catalase enzyme was decreased and the highest drop was of 50% was on the eighth day post stress. It was revealed that catalase activity was increased up to 18% on the second day after the stress and it decreased significantly with the time. The indigenous accumulation of hydrogen peroxide increased significantly in -4 treatment and four days after stress while it was reduced by 50% on the eighth day after stress. It was revealed that hydrogen peroxide application increased PAO gene expression 1.7 times compared to the control plants. Its expression was decreased by 35% at -4 bar in control plants while hydrogen peroxide treatment increased its expression by 2.8 times. These results increase the plant's resistance to drought stress and reduce the negative effects of drought stress. In this way, it reduces the negative effects of drought stress.