مجله پژوهش های ژنتیک گیاهی
سال دهم شماره 1 (بهار و تابستان 1402)

Protection of food security is one of the basic priorities of any country, which is achieved through the development and introduction of new, high-yielding and stress-resistant crop varieties. Considering the wide range of usage; human nutrition, livestock and poultry nutrition as well as use in industrial products production, maize is of special importance in agricultural development programs. To improve a trait with complex behavior and low heritability, indirect selection by other traits or a suitable index developed based on several traits can be used. In this research, 86 maize genotypes were cultivated in the form of randomized complete block design with three replications in the field in the Faculty of Agriculture, Urmia University under two normal and salt stress conditions. The measurement of the traits was done from the tassel appearance to kernel physiological maturity. In order to speed up genotype selection and increase the acuracy of selecting high yielding genotypes, four selection indices including Smith- Hazel, Pasek- Baker, Brim and Robinson were used and calculated. The results of present study revealed that selection based on the Smith- Hazel index with the highest selection efficiency (∆H) will increase the grain yield in normal and grain yield and plant height in salt stress conditions. This index, with its high correlation with the breeding value is introduced as a superior index. Based on this index, R59 and 6*/88 genotypes were introduced as the superior genotypes under normal and salt stress conditions, respectively. Nonetheless, these genotypes were recognized as the best genotypes considering the results of all other investigated indices. Identifying and introducing genotypes tolerant to salinity stress is of particular importance due to the expansion of saline lands and the limitation of access to water suitable for irrigation. Based on the above results, 6*/88 genotype is recommended for the development of promising hybrids for cultivation in areas with water or saline soil.

Apple is one of the most important economic products of Iran and the world. Apple brown rot disease (Monilinia laxa) is one of the important diseases that causes yield loss in pre-harvest and post-harvest stages. In this research, the amount of changes in some defense compounds of apple fruit, including peroxidase and catalase enzymes, following inoculation with M. laxa was assessed. Extraction and measurement of peroxidase and catalase enzymes were done at 0, 3, 6, 9 and 12 days post inoculation with M. laxa. Also, in this study, the changes in the expression of PR1 and PR8 genes in response to brown rot disease in apple fruit was recorded at 12, 24, 48 and 96 hours along with controls. The results of the analysis of variance of resistance genes expression at different time points were significant. After 48 hours, the expression of PR1 and PR8 genes was observed to be the highest compared to the control. The expression of PR1 and PR8 genes was observed to be 3 and 8 times that of the control, respectively. In this research, the expression of PR1 and R8 genes was assessed for the first time following M. laxa inoculation in apples. Results of the present study showed that reseistance genes as well as the antioxidant enzymes can help to improve resistance against apple brown rot disease as an important storage pathogens for long-term storage.

Expression of antimicrobial peptides (AMPs) in plants to resist plant pathogens as well as to produce novel AMPs for pharmaceutical applications has recently received much consideration. alfAFP, a defensin cationic peptide synthesizing in alfalfa seeds, exhibits a strong antimicrobial activity. In order to facilitate alfAFP access to the pathogen’s membrane and increase the activity of the alfAFP peptide, the alfAFP encoding sequence was fused to the C-terminal of a chitin-binding domain (CBD) from a rice chitinase encoding gene. First, the antimicrobial properties of the recombinant peptide were assessed using bioinformatics tools. Next, the pGSA1285 expression vector harboring the CBD-alfAFP heterologous DNA was transformed into Agrobacterium rhizogenes for hairy root (HR) production in tobacco. The presence of transgene, transcription, and the expression of recombinant peptide in the HRs were confirmed by PCR and semi-quantitative RT-PCR analysis, respectively. Bioinformatic analysis was used to predict the antimicrobial activity of the alfAFP recombinant peptide. The results of the 3D structure analysis revealed a β-sheet and an α-helix structure that corresponded well with the structure of plant defensins. A Knottin functional domain was also recognized, suggesting that the recombinant peptide retains its antimicrobial activity. The results of the in vitro antimicrobial activity of the alfAFP recombinant peptide using CFU test showed that the recombinant peptide had significant inhibitory effects on Pseudomonas syringae pathogen. Therefore, the chitin-binding domain provided a better access of the recombinant peptide to the pathogenic bacterial cell wall through binding to peptidoglycan, and probably the recombinant peptide was able to target the plasma membrane with better efficiency. The results of this study suggested that the expression of the CBD-alfAFP recombinant peptide in crop plants and HRs can be a promising approach to producing pathogen-resistant plants as well as to produce new recombinant pharmaceutical AMPs.

Considering the importance of maize production and the impact of water deficit stress on reducing the yield of maize, estimating the genetic components and heritability of traits for determine the breeding method under water deficit stress is essential in breeding programs. The generations drived from a cross between two inbred lines of maize including B73 (maternal line) and MO17 (paternal line), SC704 (F1) as well as F2, BC1, BC2 and F3 generations in order to estimate the genetic effects and heritability of yield, yield components and morphological traits were studied. Seven maize generations using the generations mean analysis under the full irrigation, mild and severe water deficit conditions were evaluated. The experiment was conducted in the form of randomized complete block design with 20 replications per experimental unit during two cropping seasons (2018-2019) at the Agricultural Research Station of University of Tabriz. The results of two-year combined analysis of variance and mean comparisons under three different irrigation regimes showed that water deficit stress significantly reduced all of the studied traits (except root/shoot ratio). The generations mean analysis showed the high contribution of non-additive gene effects for the genetic control of grain yield, ear diameter, number of kernel row, ear weight (in full irrigation conditions), 100 grain weight, plant height, fresh shoot weight and biological yield traits. According to these results, selection in the advanced generations and the breeding method based on hybridization can be effective to improve these traits. Also, the significant contribution of additive gene effects in controlling the inheritance of ear length, ear weight (in both stress conditions) and root/shoot ratio traits indicated that selection in early segregating generations and inbred parents can be effective for breeding of these traits and taking advantage of additive variance. Hybrid SC704 and inbred MO17 compared with the inbred B73 showed the lowest variation percentage under the water deficit stress conditions, which indicated their high yield potential and stability in the stress conditions.

Eggplant is a highly nutritious vegetable that is widely consumed. The aim of this study was to evaluate the genetic diversity between eggplant accessions from the National Plant Gene-Bank of Iran. In the first year, a preliminary evaluation was conducted using 168 accessions. Based on preliminary evaluation results, 40 accessions were selected for complementary evaluation in the second year. The evaluation was based on 23 quantitative and qualitative traits. The results of the preliminary evaluation showed statistically significant (P<0.01) differences between accessions for all traits. Fruit shape frequencies were rounded (35.89 percent), elongated (32.18 percent), oval (13.67 percent), Semi-elongated (13.15 percent), and mace-shaped (5.11 percent). In the complementary evaluation, there were significant differences between accessions for all traits. Qualitative traits such as flower color (1.56) and fruit shape (1.53) exhibited the highest genetic variation, while fruit color (0.5) showed the lowest. Cluster analysis analysis results revealed four groups for accessions and the highest (22.34) and least (0.12) genetic distances between 1 and 2 and between 7 and 21accessions, respectively. Factor analysis showed that the first three factors explained 68.06 percent of total variation in data. The first and second factors were related to yield and yield components, respectively. Also, fruit yield traits showed high heritability and there was significant genetic correlation between these traits. Therefore, high heritable and high-scoring traits in these factors should be considered when selecting progenies in segregating populations for improvement in terms of fruit yield and shape.

Evaluating the population structure is essential for understanding diversity patterns, choosing proper parents for crossing, accurate identification of genomic regions controlling traits, and evolutionary and kinship relationship studies. In this research, the genetic structure of a wheat population was studied in a panel consisting of 383 Iranian wheat genotypes of hexaploid (cultivars and landraces) and tetraploid species based on distance-based methods (principal component analysis and discriminant analysis of principal component). For this purpose, 16270 single nucleotide polymorphism (SNP) markers obtained by the GBS technique were used. According to the results, almost a quarter of the total variance was belonged to the diversity between populations, and the Fst coefficient between cultivars and landraces was equal to 0.15. In contrast, the above coefficient between tetraploid samples and hexaploid landraces was high and equal to 0.44. Genome D had the lowest value of Fst index and chromosome 4B showed the highest Fst coefficient, and other genetic diversity indices. Although the PCA biplot distinguished hexaploid wheat cultivars from landraces, it was unable to distinctly separate tetraploid genotypes from other genotypes. Accurate evaluation of the population structure with the DAPC method was able to identify and separate the predetermined successfully groups, suggesting that the DAPC approach maximizes the differentiation between groups and minimizes the changes within the group. Partial admixture between cultivars and landraces of hexaploid wheat can be related to gene exchange between these two groups or perhaps their wrong labeling at the time of collection. In general, the results of this study provided valuable information about the genetic differentiation of Iranian tetraploid and hexaploid wheat, which can be used in future wheat breeding programs. Further, protecting these genotypes in gene banks is necessary for different strategies.

In this research, 15 bread wheat genotypes along with Aftab variety as a control variety were implemented with 4 replications in the form of randomized complete block design for 3 crop years (2016-2019) at Sarab Chengai Station in Khorramabad. The likelihood ratio test (LRT) showed that the genotype-year interaction effect was significant for grain yield. Based on this, singular value analysis (SVD) was performed on the matrix of best linear unbiased predictions (BLUP) of genotype × year interaction to evaluate the stability of genotypes. The scree plot showed that the first principal component accounted for 71.7% and the second principal component accounted for 28.3% of the matrix changes resulting from the best unbiased predictions of the genotype interaction per year. The biplot of the first principal component of the environment against the nominal yield also showed that genotypes No. 9, 12 and 13 had a negligible contribution to the genotype × year interaction and had higher general stability. Also, the biplot of grain yield against the weighted average of absolute scores (WAASB) placed the genotypes in four regions, so that genotypes No. 15, 16, 12, 11, and 10 are in the fourth region due to high stability (low values WAASB) and magnitude of response variable (high performance) were identified as superior genotypes. The WAASBY index (weighted average of WAASB stability and performance) identified genotypes No. 15, 16, 12, 10, 11, 14, 9 and 4 as stable and high yielding genotypes. In general, based on WAASB and WAASBY indices and their comparison, genotypes 15, 16, 12, 11 and 10 were selected as the best genotypes that can be recommended for cultivation in similar climates.

To investigate the genetic structure of different sesame traits, 7 genotypes, including Ardestan, Sirjan, Fars, Sabzevar, Jiroft, Oltan and TS-3 were studied in the form of a 7 x 7 one-way diallel design in the research farm of the Faculty of Agriculture at University of Birjand during 2015-2018.The traits measured included plant height, height to the first capsule, number of auxiliary branches, number of leaves, leaf length, days to 50 % flowering, days to 90 % flowering, days to physiological maturity, number of capsules per plant, biological yield, grain yield, harvest index, number of seeds per capsule, capsule weight, capsule length, capsule width, chlorophyll a, b and total chlorophyll, oil and protein percentage.Hayman′s variance analysis showed that there were significant components a, b and b3 in all traits and components b1 and b2 in most traits. Parameters D, H1, and H2 were significant and the parameters F, h2 and E were not significant for most traits. The average degree of dominance (√H1/D) showed incomplete dominance and over dominance for all traits. The H2/(4H1) parameter was less than 0.25 in all traits except the day to 50 % flowering, suggesting that increasing and decreasing genes did not have symmetrical distribution among the parents. The parameter (√(4DH1)+F)/√(4DH1)-F ) showed symmetrical and asymmetrical distributions for the studied traits. In most of the traits, there was a dominant gene block controlling the traits. Broad sense and narrow sense heritabilities ranged 0.47-0.99 and 0.17-0.98, respectively. In general, all traits were controlled by genes with additive and dominance effects, so it is possible to select and produce hybrids in sesame. Considering that Fars, Oltan and TS-3 genotypes had the most dominant alleles, it is recommended that in future studies, attention should be paid to these three genotypes.

To evaluate the expression pattern of genes encoding antioxidant enzymes catalase, ascorbate peroxidase and polyphenol oxidase under iron deficiency conditions in Fe- efficient (Pishtaz) and -inefficient (Falat) bread wheat cultivars, a CRD (completely randomized design) based factorial experiment was conducted with three replications. The cultivars were grown under iron deficiency (Less than 1.5 mg Fe/kg soil) and compared with normal conditions (10 mg Fe/kg soil). The relative expression levels of the above-mentioned genes were measured using Real-time PCR technique in the leaves and roots of the cultivars at two growth stages: vegetative (one month after germination) and reproductive (30% of heading). The results revealed a remarkable enhancement in calatalse expression in the roots of both cultivars in the vegetatative stage but it was higher in Fe-efficient cultivar than -inefficient one. The expression of this gene was decreased in leaves at the same stage as well as in the roots of both cultivars in the vegetative stage. The expression level of ascorbate peroxidase gene in the reproductive stage in the roots of Fe-inefficient cultivar was higher than that of -efficient one. In the vegetative stage, the expression of this gene increased in the leaves and roots of Fe-efficient cultivar, but it was decresed in Fe-inefficient cultivar. The relative expression level of polyphenol oxidase gene in the vegetative stage under iron deficiency conditions in the leaf increased almost three times, compared to the roots, while the expression of this gene decreased in the reproductive stage in both leaves and roots. By increasing the expression of both catalase and ascorbate peroxidase genes in the roots of both cultivars in the reproductive stage under iron deficiency conditions, it seems that bread wheat cultivars might reduce the deletrious effects of stress and maintain yield through transferring much iron to the seeds in the seed filling stage. The findings of the present study may increase our understanding of the important role of genes encoding antioxidant enzymes in Fe deficiency stress conditions.

The current research was carried out to evaluate genetic diversity of 18 common bean cultivars and promising lines and to determine SSR and SCoT informative markers associated with 14 seed characteristics including the number of seeds per pod, 100 seed weight, seed length, seed width, the contents of crude protein, total soluble sugar, starch content, crude fat, iron, calcium, magnesium, zinc, uronic acid, and mineral ash. The polymorphism information content (PIC) values varied from 0.2 to 0.5 with an average of 0.39 for the SSR markers and from 0.19 to 0.42 with an average of 0.34 for the SCoT markers. The total average resolving power of SSR and SCoT markers were 1.54 and 5.34, respectively, indicating higher efficiency of SCoT markers than SSR markers for the diversity analysis. The common bean studied genotypes were clustered into three distinct groups for both markers based on the Complete Linkage method. Principal coordinate analysis (PCoA) for the SSR markers revealed that the first two principal components justified 59.05% of whole variation. For the SCoT marker, on the other hand, the fraction of variances explained by the first two principal components was equal to 25.43 indicating a better distribution of SCoT markers than SSR markers in the common bean genome. Analysis of molecular variance based on the grouping obtained from cluster analysis showed that the diversity within the group based on SSR and SCoT markers was equal to 89 and 78%, respectively. The results of regression analysis for the studied markers and the bean seed characteristics showed the existence of a significant relationships between a single marker with the several studied traits. This could indicate the association or linkage of the marker locations. Twelve out of 14 of the investigated common bean seed characteristics showed a significant relationship with at least one molecular marker.