Iranian Journal of Genetics and Plant Breeding
Volume:8 Issue: 2, Oct 2019

Dog Rose is one of the most important species in Rosaceae family used as a medicinal plant and a rootstock for ornamental roses. This species is native to Iran, therefore, identification of indigenous genotypes of this species is important for genetic preservation or breeding purposes. Genetic diversity estimation of plant materials is one of the important pre-breeding activities in breeding crops. In this study, genetic variation of 23 genotypes of R. canina was investigated using fifteen ISSR markers. The genotypes were collected from three regions of Ardabil province (Namin, Nir and Khalkhal). The results showed that all primers generated clear and consistent polymorphic bands (77% polymorphism) but, ISSR-15 revealed a high numbers of polymorphic bands and was superior to other markers. Also, the ISSR-15 produced the highest number of polymorphic bands with seven scorable bands, while the UBC-823 and UBC-825 markers had the least number of bands (3 bands). The clustering pattern of genotypes was related to geographic regions. The genotypes from Khalkhal region were separated from other genotypes (Nir and Namin genotypes) in cluster analysis. The results of the current study indicated that the ISSR markers separated genotypes based on geographic region. The best way to select parents is to use genotypes with high genetic distances. Therefore, we determined the genetic distance among genotypes. According to the results, ISSR is an efficient marker system that can provide excellent information among R. canina genotypes. Finally, the obtained results indicated that the R. canina genotypes investigated in this research have a wide genetic diversity.

Drought stress is one of the most important environmental stresses affecting plant growth, yield and crop production around the world. It is believed that arbuscular mycorrhizal fungi are used for protecting plants against drought damage.Vesicular-arbuscular mycorrhizal fungi have been used in recent years to cope with water stress in many plants. In this study, the relationship between water deficit stress and mycorrhizal fungi were analyzed with mycorrhizal dependence index and chlorophyll stability in sesame (Sesamum indicum L.). The experiment was conducted in a split-plot design based on randomized complete blocks with three replications in the research field of Agricultural Research Center, West-Azerbaijan during years 2015 and 2016. The main factors consisted of normal irrigation, moderate and severe water stress and subplots included two different species of mycorrhizal fungi namely, Funneliformis mosseae and Rhizophagus intraradices. A non-inoculated plant served as the control. Mean comparison based on 2-years data showed that with increasing severity of water stress, biological water use efficiency (WUBE), oil harvest index (OHI) and protein harvest index (PHI) decreased. Using two kinds of mycorrhizal fungi F. mosseae, R. intraradices compared to non-inoculated, caused an increase in WUBE and PHI about 28 and 20% and 6 and 2%, respectively. Also in three different irrigation conditions, the effect of F. mosseae and R. intraradices was similar on chlorophyll b stability index (CSIb). The maximum and minimum WUBE (0.96 and 0.43 kg/m3), OHI (17.61 and 10.03%) and PHI (9.36 and 5.80%) were obtained under optimal irrigation and severe drought stress conditions, respectively. The maximum (34.69%) and minimum (20.26%) of mycorrhizal dependence index based on biological yield (MDIBY) were observed under severe drought stress and optimal irrigation conditions, respectively. Therefore, inoculation with mycorrhizal fungi (measured by MDIGY and MDIBY) under drought stress caused an increase in the chlorophyll (measured by TCSI). Increasing the chlorophyll led to an enhancement in the photosynthesis and promoted WUEE and WUBE. Improvement of the WUEE and WUBE caused an increase in oil and protein (measured by OHI and PHI). In severe and moderate water stresses mycorrhizal dependence index based on grain yield (MDIGY) and MDIBY increased compared to optimal irrigation. It can be concluded that for achieving high WUEE, WUBE, OHI and PHI, TCSI and as a result tolerance to the water stress can be increased.

In order to evaluate the genetic variation in Iranian summer savory accessions, different accessions were analyzed using multivariate and univariate analysis. Results indicated that there were significant differences in some traits. The mean comparison analysis using least significant difference (LSD) test revealed significant differences among the accessions understudy. In this regard, the highest significant means for traits were related to Mashhad, Tabriz 1, Tabriz 2, and Kermanshah accessions. Results of correlation analysis showed high positive correlation between total fresh weight and stem fresh weight and negative correlations between the number of leaflet per main stem and distance of internodes. This can be effective for investigating the interactions between traits. Based on the results of factor analysis, significant traits in the first factor, including total fresh weight, stem fresh weight, root fresh weight as well as total dry weight, stem dry weight, and root dry weight, were highly correlated with each other and were independent of the other factors. Therefore, the first factor was considered as the weight factor due to its high value of “communality” in the traits related to the weight. According to the cluster analysis, 29 accessions clustered into four groups, with those having similar phenotypes clustering into the same group. The discriminant analysis confirmed the accuracy of the grouping to be 97.2%. Considering the grouping, no relationship was found between the genetic variation and geographical distance of the accessions. However, the accessions in separate groups can be selected for breeding programs. The results of the present study can be considered useful for identifying and managing the germplasm of the Iranian summer savory.

The WRKY gene family encodes a large group of transcription factors that regulate genes involved in plant response to biotic and abiotic stresses. Sorghum is a notable grain and forage crop in semi-arid regions because of its unusual tolerance against hot and dry environments. In this study, we performed a genome-wide analysis of WRKYs using a genome assembly of sorghum bicolor. First, all possible WRKY gene sequences as well as all possible WRKY protein sequences in the Sorghum bicolor genome database were identified using the NCBI website. A set of 85 WRKY genes was identified in the S. bicolor genome and classified into three groups (I–III). Among the members of the group I, the SbWRKY13 had a different and novel zinc finger motif as compared to other members of this group. It was also found that mutations occurred at R, K, Y and Q in the conserved WRKYGQK sequence. No complete gene duplication was found in gene copy number investigation, suggesting that the expansion of SbWRKY genes was not necessarily based on the gene duplication events or duplication of SbWRKY genes had probably happened in the past times. Gene cluster analysis showed that the number of genes on chromosomes were positively correlated with the number of clusters. The study of amino acid composition revealed that totally in all groups, Alanine and Proline were the most frequent residues while Cysteine had the lowest frequency. The study of introns in the SbWRKY domain showed that the majority of SbWRKY genes had two types of introns in their WRKY domains (phase 0 and phase 2). Also, investigation of conserved known motifs revealed that there were six, two and one known motifs outside of the region of the SbWRKY domain for groups IIa, IIb and IIc, respectively. The results describe evolution and functional differentiations of WRKY transcription factors in Sorghum bicolor.

Drought stress is one of the important factors that restrict crop production in the world. This studywas conducted to investigate defense gene expression in response to drought stress, and also to evaluate the drought tolerance and its mechanism in rice cultivars based on randomized complete block design in two separate environments (drought stress and non-stress). The rice cultivars used included two commercial cultivars, i.e., Ahlemi-Tarom, Sepidrood, and three promising lines of fourth mutant generation called 4, 94 and 95 tested on the research farm at Gonbad Kavous University in 2018. For carrying out the drought stress-related experiment, irrigation was completely cut off 40 days after the transplantation (a stage with maximum tillering) until the end of the growth period. In seeding stage, each plant leaf was separately sampled in each block (under the stress and non-stress conditions). TBARM, superoxide andhydrogen peroxide contents and oxidative-stress related gene expression including superoxide dismutase, catalase, ascorbate peroxidase and glutathione peroxidase were measured. Results indicated that the drought-tolerant mutant lines had lower TBARM, superoxide andhydrogen peroxide contents compared to the studied cultivars. The mutant lines 94, 4 and 95 and Ahlemi-Tarom and Sepidrood had the highest to lowest levels of gene expression and yield in drought stress condition, sequentially. Accordingly, there was a complete correlation between the decreases in TBARM, superoxide andhydrogen peroxide and an increase in the level of gene expression. Mutant 94 had the highest yield and probably a suitable genetic potential in relation to drought tolerance. Therefore, the mentioned mutant is recommended for carrying out further studies.

Mollusca are one of the most diverse animal phyla whose phylogeny is considered as a controversial subject. Although some groups were traditionally classified as mollusca, they need to be identified again. High diversity of mollusca has created considerable taxonomic problems and despite their importance in marine biota, deep phylogenetic relationships of mollusca have scarcely been investigated. The aim of this study was to determine genetic diversity and differences between mollusca species in waters of Bandar Lengeh (Persian Gulf) of Iran. A clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by PCR, and then, after examining the clones, selected clones were sequenced. The determined clone sequences were analyzed by a similarity search of the NCBI GenBank database using BLAST. Also, the fixation index (FST) factor was used in order to measure and understand the genetic differences between studied populations. In this study, seventeen sequences were identified belonging to two classes of Bivalvia and Gastropoda and they were used for phylogenetic analysis. According to the allele frequencies at each locus, FST value was significant in samples of Bandar Lengeh meaning that migration is in the lowest rate in the studied region. The present research project exhibited that clone library of 18S rDNA might be accounted as a beneficial tool to identify marine specimens and estimate the actual species diversity in marine environments. Moreover, these findings confirmed the effective role of molecular studies for the identification and taxonomy of speciesfrom the natural resources to obtain reliable data.