مجله پژوهش های ژنتیک گیاهی
سال هشتم شماره 2 (پاییز و زمستان 1400)

Black poplar (Populus× euramericana Dode Guinier) is an industrially important tree with broad applications in wood and paper, biofuel and cellulose-based industries as well as plant breeding programs and soil phytoremediation approaches. Here, we have focused on development of direct shoot regeneration and Agrobacterium-mediated transformation protocols using the in vitro internodal stem tissue from hybrid black poplar. To obtain efficient plant regeneration, the internodal stem explant was cultured on SIM and RIM medium containing different concentrations of BAP × IBA and IBA × NAA, respectively. The crucial factors involved in genetic transformation have been evaluated to achieve Agrobacterium-mediated transformation protocol. We achieved fast and highly potential shoot regeneration from the explants cultured on SIM containing BAP 0.5mg/L and IBA 0.05mg/L with 28.57 shoots per explant. The normal roots developed from the plantlets cultured on RIM containing IBA 0.1mg/L and NAA 0.05mg/L and 100% of the regenerated plants were hardened and transferred to the greenhouse condition. Our results indicated that 0.5 µM Basta® could provide a stringent selection for the inhibition of non-transformed cells. We also obtained the highest transformation efficiency of 93.33% through preculturing the explants for 6 days and dipping into IM medium containing A. tumefaciens strain LBA4404 (OD600 = 0.6) and 100 µM AS for 10 min. The Southern blotting analysis, RT-PCR and GUS histochemical analysis were confirmed the stable single or two-copies gus transgenesis in the genomic DNA and its expression in the selected T0 generation plants. The findings indicate that these protocols could be used for genetic engineering approaches in hybrid black poplar.

Evaluation of genetic diversity is the key principal for plant breeding, providing an opportunity to discover novel characters and alleles for breeders. In the present study, 69 durum wheat genotypes were investigated for genetic diversity using several inter-simple sequence repeat (ISSR) markers. Sixteen ISSR primers amplified a total of 163 fragments, which out 160 fragments were polymorphic. The mean values of polymorphic information content (PIC), resolving power (Rp) and marker index (MI) indicated that the used ISSR primers could be exploited for further assessing relationships among investigated genotypes and population structure analysis. The results of the molecular analysis of variance showed that the genetic variation within populations is more than between them. Based on genetic variation parameters, the highest number of observed alleles (Na), Shannon’s information index (I) and the percentage of polymorphic loci (PPL) were found in Iranian landraces. Cluster analysis and population structure grouped all investigated genotypes into three main clusters and six subpopulations, respectively. In conclusion, our results revealed the high rate of genetic diversity within Iranian landraces, so this germplasm can be used as a valuable gene source for the selection of parent lines and use of them in durum wheat breeding programs.

Black cumin (Nigella sativa) is a medicinal plant of the Ranunculacea family which raised attention due to its pharmaceutical properties. Medical significance of N. sativa mainly attributed to its oxygenated monoterpenes which are biosynthesized via the methyl erythritol phosphate (MEP) pathway located in plastids. In this study, the essential oil components of leaves, flowers, and developmental stages of seed including half black seeds, soft black seeds, and hard black seeds were analyzed in N. sativa. Whereas no terpene was detected in flowers and leaves, seeds were found to be the major site of biosynthesis and accumulation of terpenes, and the amount of terpene compounds changed during seed maturation. The essential oil consists of monoterpenes (more than 99%) and sesquiterpenes (less than 1%). In order to improve our understanding of monoterpene metabolism, the partial sequence of a hypothetical monoterpene synthase (NsTPS2) was isolated from N. sativa plant using RACE-PCR technique. This monoterpene synthase was identified from RNA sequencing data from soft black seeds. Except of the highly conserved DDXXD motif in NsTPS2 which is necessary to validate monoterpene synthases, no other conserved regions of other identified monoterpene synthases were observed. Dendrogram analysis revealed that NsTPS2 had the highest homology with a terpene synthase (72.89%) from Aconitum carmichaelii and these two sequences were grouped in the same group. Nigella sativa and Aconitum carmichaelii both belong to the Ranunculacea family. This indicates that the genetic information of plants of the Ranunculacea family can be used to isolate different monoterpene synthase. The results of this research can be useful in genetic manipulation and metabolic engineering of Nigella sativa.

Festuca is one of the largest genera of the grass family, which has more than 600 species with different ploidy levels. The aim of this study was to estimate the genetic diversity within 22 populations of three species of Festuca (Festuca arundinacea, F.rubra and F.ovina) using a seed storage protein electrophoresis pattern. These species showed a significant variation in the number of protein bands from 5-13. The highest number of bands was found in G17 (F.rubra) and the lowest number of protein bands was in G5 (F.ovina). Band number 14 was only observed in G3. It is suggested that this band can be considered as a specific band for the identification of this genotype. According to the results of AMOVA analysis, there is a high level of genetic diversity within the species rather than between species that can be due to the out-crossing nature of this genus. According to observed differences for variation parameters among the three studied species, it is concluded that they have dissimilar genetic structures. The results of cluster analysis based on seed storage protein profiles in evaluated genotypes using Euclidean distance matrix and UPGMA method showed four groups. The lowest similarity coefficient was between G14 and G15 (F.arundinacea) with G6 (F.ovina). Hence, it is suggested that they evolved from a different evolutionary process and it is suggested to use them as the parents of new synthetic varieties. The observed diversity in the seed protein pattern in the three species of Festuca, can be explained by allogamy-induced-heterozygosity, species difference or population collection from various regions.

Genus Allium L. contains very taxonomically complex sections, especially the subgenus Melanocrommyum. The systematic position of the species in each section has been revised many times over time. In the present study, the relationship between 32 ecotypes belonging to 10 different species of Allium was investigated using ISSR markers. The nine primers used produced 166 polymorphic bands (average 18 bands per primer). Among the primers used, ISSR873 primer with 27 bands made the most, and ISSR4 primer with two bands had the lowest polymorphic bands. The PIC of the markers ranged from 0.04 to 0.43. Cluster analysis by UPGMA method based on molecular markers divided the studied ecotypes into four groups. The clustering and principal coordinate analysis results showed that most morphologically similar species were grouped in closed clusters. According to Dice similarity coefficient, the highest percentage of similarity was shown between Allium stipitatum and Allium saralicum ecotypes (72 percent) from the Melanocrommyum subgenus, and the lowest similarity was obtained between Allium tripedale and Allium iranicum ecotypes (12 percent). The ecotypes with the lowest similarity percentage belong to the subgenus Allium and Nectaroscordum, which are placed in separate clusters. Based on the results, the ecotypes of Pseudoprason, Melanocrommyum, and Procerallium sections showed the highest affinity. In general, it can be concluded that ISSR markers are useful for classifying Allium species and have sufficient potential for phylogenetic studies of species. In addition, due to significant genetic diversity among the studied ecotypes of wild Allium species, this diversity can be used in future breeding programs of crop.

Identifying selection indices is the most important step of a breeding project that aims to improve grain yield. The definition of the selection index is usually done by evaluating the variables in multivariate statistical methods. In the present study, the relationship between grain yield and its components in bread wheat genotypes was determined by multivariate statistical methods. The experiment was conducted in a randomized complete block design with 3 replications in the research farm of Gorgan University of Agricultural Sciences and Natural Resources in the 2018-19 crop years. Ten commercial cultivars of bread wheat along with their offspring from direct and inverse crosses in a dialysis arrangement were evaluated for morphological and phenological traits, especially grain yield and its components. The results of genotypic and phenotypic correlation coefficients showed a positive and significant correlation (at 1% probability level) between grain yield and spike length, spike weight, number of fertile tillers, number of seeds per spike, number of spikes per spike, 1000-seed weight, biological yield and harvest index. Based on the results of stepwise regression analysis, biological yield, harvest index, number of grains per main spike and main spike weight were entered into the regression model, respectively, and explained a total of 98% of the variation in grain yield. Based on the results of path analysis, biological yield had the highest direct effect on grain yield. After biological yield, the most direct effect on grain yield was related to the weight of main spike. Also, by considering eigenvalues greater than one in factor analysis, 8 hidden factors were identified that explained a total of 75.18% of the data changes. In general, it can be concluded that biological yield, harvest index, number of seeds per spike and weight of spike compared to other traits can be used as appropriate indicators in breeding programs to select high-yield genotypes in field conditions. Genotypes Alo, Ehsan♂ × Gonbad♀ and Ehsan had the highest value for the studied traits, which can be used in future breeding researches.

Today, antimicrobial peptides are known as a new generation of antibiotics for treatment of microbial diseases in human and animals and protecting plants against different pathogens. Heveins are a group of antimicrobial peptides which are considered as one of the most important groups of antimicrobial peptides due to the very high diversity and expression in different plant organs as well as the effective role in responding to biotic and abiotic stresses. The main purpose of the current study was identifying and isolation of hevein genes in barley and study of characteristics and their expression in different tissues and environmental conditions. To this purpose, all hevein protein sequences were retrieved from NCBI database. The hevein consensus sequence was obtained from alignment of retrieved sequences. After obtaining the consensus sequence, this sequence was aligned against the barley genome using tBLASTn tool. The resulting sequences were analyzed to determine the full-ORF, and to prediction of functional domains, signal peptides, subcellular localization, physicochemical properties, amino acid frequency and antimicrobial activity. The complete coding sequence of hevein genes were amplified by PCR. In this study, thirteen hevein genes, with an average ORF length of 813 bp, were identified, isolated and sequenced in barley. Hevein genes isolated from barley showed a high similarity with plant heveins in terms of gene and protein sequences, as well as structural and functional characteristics. The results showed that barley Heveins such as other plant Heveins have no introns or have only one intron, and the presence of secretory peptide signals, extracellular aggregation, the presence of ChtBD1 functional domains in all of them and Lyz-like functional domains in some of them was confirmed. The results also showed that antimicrobial activity and maximal expression in roots and reproductive organs as well as expression in response to biological and non-biological stresses are other features of these proteins. The findings of the current study increase our understanding of the effect of Hevein genes on plant biological processes such as growth and development, as well as the response to biotic and abiotic stresses.

Various strategies have been developed to reduce water consumption in rice cultivation, including rice cultivation in water-saturated soil, drying and wetting of the soil (periodic irrigation), and aerobic rice cultivation. In this study, in order to identify and grouping rice cultivars suitable for aerobic cultivation, 34 cultivars of native and improved rice cultivars were selected and evaluated. Factor analysis based on principal components analysis based on all traits showed that 6 factors were extracted with special values of more than one. These 6 factors, after the Varimax rotation, justify the 6 main and independent factors, justifying 78.08% of the total variation. In the first harvest, cluster analysis using WARD method, cultivars were grouped into 4 groups, which cluster 3 being the largest cluster. Discriminant analysis of first harvest, showed that all cultivars were grouped correctly. In canonical discriminant the first two canonical functions with eigenvalues greater than one explained a total of 88.9% of the variance. In cluster analysis based on the average of the data obtained from Raton product, genotypes were divided into two different groups. The genotypes of the first group were higher than the genotypes of the second group in terms of yield and yield components and were introduced as superior genotypes. Heritability with genetic improvement for leaf area duration, number of seedling (grown plants), number of spikes per unit area, number of full seeds and degree of maturity showed that these traits can be transferred to hybrid offspring and selections based on these traits are effective.

The selection of genotypes based on multiple traits is a fundamental issue and an important part of the process of plant breeding. In the present study, the efficiency of selection indices based on phenological, morphological and physiological traits was studied to improve sesame grain yield. The evaluation of 25 sesame populations was realized in a completely randomized design with 10 replications under Urmia conditions in 2017.The results showed that phenotypic and genotypic correlations between grain yield and No. of capsules per plant, No. of grains per capsule, No. of branches, leaf temperature, leaf index and biological weight were positive and significant. By regression and path analysis, the No. of capsules and No. of branches were identified as the variables of the first-order cause and biological weight, harvest index, leaf index, plant height and chlorophyll as the second-order cause variables, among which only plant height had a direct negative effect. In order to obtain selection indices, two optimal and basic methods and ten different vectors of economic values of traits were used. The vectors were based on the analysis of correlation, regression, path and broad sense heritability. The third and fourth indices, in which the first-order cause entered the model, showed high relative efficiency and in terms of these two indices, and the sesame populations with code number of 12, 17, 18 and 19 populations were identified as the most desirable populations. Finally, it is suggested that the efficiency of these selection indices be evaluated in the field

In breeding programs determination of gene effects and general and specific combining ability for screening of test crosses is necessary. In order to estimate the genetic variance components and the general and specific combining ability of sweet corn lines, an experiment was conducted using 8 sweet corn S6 inbred lines (including 4 maternal and 4 paternal lines) by line × tester mating design in 2019, at the Agricultural and Natural Resources Research and Education Center of Khorasan Razavi Province, Mashhad, Iran. The obtained test cross hybrids were evaluated in a randomized complete block design with 3 replications in 2020. The results of line, tester and line × tester analysis for most of measured traits showed significant differences (p < 0.05). The σ2gca/σ2sca ratio for grain yield was equal to 0.1, showed that while both additive and dominance effects play a role in controlling this trait, but dominance effect was higher. The results for general combining ability of L3 and T1 lines showed positive and significant GCA effect for grain yield. Also, the specific combining ability of grain yield showed that T4 × L2, T1 × L3 and T3 × L1 had the highest SCA rate. In this study, in terms of grain yield, T1 × L3, T4 × L2 and T1 × L4 with 33.96, 30.47 and 27.85 tons per hectare had the highest green ear yield, respectively. These combinations can be as the hybrids with high yield potential in advanced breeding programs for release of new sweet corn varieties.