Triterpenic acids (TAs), a large group of natural compounds with diverse biological activity, are produced by several plant taxa. Betulinic, oleanolic, and ursolic acids are the most medicinally important TAs and are mainly found in plants of the mint family. Metabolic engineering is strongly dependent on identifying the key genes in biosynthetic pathways toward the products of interest. In this study, gene expression tracking was performed by transcriptome mining, co-expression network analysis, and tissue-specific metabolite-expression analysis in order to identify possible key genes involved in TAs biosynthetic pathways. To this end, taxa-specific degenerate primers of six important genes were designed using an effective method based on the MEME algorithm in a phylogenetically related group of sequences and successfully applied in three members of the Lamiaceae (Rosmarinus officinalis, Salvia officinalis, and Thymus persicus). Based on the results of in-depth data analysis, genes encoding squalene epoxidase and oxido squalene cyclases are proposed as targets for boosting triterpene production. The results emphasize the importance of identifying key genes in triterpene biosynthesis, which may facilitate genetic manipulation or overexpression of target genes.

Triterpenoid saponins are a diverse group of bioactive compounds, which are used for possessing of many biomedical and pharmaceutical products. Generally, squalene synthase (SQS) is defined as an emerging and essential branch point enzyme far from the major pathway of isoprenoids biosynthetic and a latent adjusting point, which manages carbon flux into triterpenes biosynthesis and sterols. The present study deals with the detailed characterization of SQS by bioinformatics approaches to evaluate physicochemical properties, structural characteristics including secondary and 3D structure prediction and functional analysis from eight plants related to Fabaceae family and Arabidopsis thaliana. Bioinformatics analysis revealed that SQS proteins have two transmembrane regions in the C-terminal. The predicted motifs were used to design universal degenerate primers for PCR analysis and other molecular applications. Phylogenetic analysis showed conserved regions at different stretches with maximum homology in amino acid residues within all SQSs. The secondary structure prediction results showed that the amino acid sequence of all squalene synthases had α helix and random coil as the main components. The reliability of the received model was confirmed using the ProSA and RAMPAGE programs. Determining of active site by CASTp proposes the possibility of using this protein as probable medication target. The findings of the present study may be useful for further assessments on characterization and cloning of squalene synthase.

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by these QTLs varies from 7.07 to 39.04%. Highest LOD scores were obtained for the leaf to stem ratio on chromosome 2H. QTLs for forage quality indexes (total digestible nutrient, dry organic matter digestibility, leaf to stem ratio and seed to forage ratio) were found on chromosomes 1H, 2H, 3H and 5H. QTLs for forage quantity indexes (forage wet and dry matter) were mapped on chromosomes 1H, 2H, 3H and 5H. Mapped QTLs appear to be stable between locations. Therefore, gain through marker-assisted selection (MAS) in this population would be efficient.Salt stress as one of the most important abiotic stress, plays an important role in the yield reduction of crop plants worldwide. It is now recognized that tolerance to salinity is genetically and physiologically complex and also inherited quantitatively. Molecular marker aided selection technique for salinity tolerance, would accelerate breeding progress by increasing selection efficiency. Barley is a short-season, early maturing, diploid and self pollinating crop, thus it is an ideal model plant for genetic and physiological studies of salinity tolerance. To map the Genes/QTLs for salinity tolerance in barley, and to determine the portion of each QTL in the phenotypic variation of the related traits, 72 doubled-haploid lines derived from a cross between Steptoe and Morex were investigated. This experiment was carried out under hydroponic system in botany laboratory of Zabol University in 2008. It was arranged as a completely randomized factorial experiment, with 3 replicates and four salinity levels (0, 5, 10, 15 ds/m). Phenotypic traits such as chlorophyll contents, chlorophyll florescence (Fo, Fv, Fm/Fv), prolin and carbohydrate rates, relative water content (RWC), germination percentage, coleoptiles length, stem and radicle length and their proportion, dry and wet weight of root and shoot were measured. QTL analysis was carried out using genetic linkage map derived from 327 RFLP molecular markers and QTL cartographer software with composite interval mapping method. In general we found 111 QTLs for the all traits (20 QTLs for free salinity condition, 22 QTLs for first salinity level, 14 QTLs for second salinity level, 30 QTLs for third salinity level and 25 QTLs for the mean of these four condition). Phenotypic variations that were explained by these QTLs, changed from 7.99 to 29.55. The highest and the lowest phenotypic variances were related to stem length in proportion to radicle length in free salinity condition and Fm/Fv in first salinity level, respectively. LOD score was ranged in 2.52-6.67. The highest and the lowest LOD were attained for the QTLs of stem length in proportion to radicle length in free salinity condition (Q2sh/rs0) and stem length in first salinity level (Q2shs1). Mapped QTLs appear to be unstable between conditions. Therefore, gain through marker-assisted selection (MAS) in this population for salt tolerance would be inefficient.Salt stress as one of the most important abiotic stress plays an important role in the yield reduction of crop p...

by these QTLs varies from 7.07 to 39.04%. Highest LOD scores were obtained for the leaf to stem ratio on chromosome 2H. QTLs for forage quality indexes (total digestible nutrient, dry organic matter digestibility, leaf to stem ratio and seed to forage ratio) were found on chromosomes 1H, 2H, 3H and 5H. QTLs for forage quantity indexes (forage wet and dry matter) were mapped on chromosomes 1H, 2H, 3H and 5H. Mapped QTLs appear to be stable between locations. Therefore, gain through marker-assisted selection (MAS) in this population would be efficient.Salt stress as one of the most important abiotic stress, plays an important role in the yield reduction of crop plants worldwide. It is now recognized that tolerance to salinity is genetically and physiologically complex and also inherited quantitatively. Molecular marker aided selection technique for salinity tolerance, would accelerate breeding progress by increasing selection efficiency. Barley is a short-season, early maturing, diploid and self pollinating crop, thus it is an ideal model plant for genetic and physiological studies of salinity tolerance. To map the Genes/QTLs for salinity tolerance in barley, and to determine the portion of each QTL in the phenotypic variation of the related traits, 72 doubled-haploid lines derived from a cross between Steptoe and Morex were investigated. This experiment was carried out under hydroponic system in botany laboratory of Zabol University in 2008. It was arranged as a completely randomized factorial experiment, with 3 replicates and four salinity levels (0, 5, 10, 15 ds/m). Phenotypic traits such as chlorophyll contents, chlorophyll florescence (Fo, Fv, Fm/Fv), prolin and carbohydrate rates, relative water content (RWC), germination percentage, coleoptiles length, stem and radicle length and their proportion, dry and wet weight of root and shoot were measured. QTL analysis was carried out using genetic linkage map derived from 327 RFLP molecular markers and QTL cartographer software with composite interval mapping method. In general we found 111 QTLs for the all traits (20 QTLs for free salinity condition, 22 QTLs for first salinity level, 14 QTLs for second salinity level, 30 QTLs for third salinity level and 25 QTLs for the mean of these four condition). Phenotypic variations that were explained by these QTLs, changed from 7.99 to 29.55. The highest and the lowest phenotypic variances were related to stem length in proportion to radicle length in free salinity condition and Fm/Fv in first salinity level, respectively. LOD score was ranged in 2.52-6.67. The highest and the lowest LOD were attained for the QTLs of stem length in proportion to radicle length in free salinity condition (Q2sh/rs0) and stem length in first salinity level (Q2shs1). Mapped QTLs appear to be unstable between conditions. Therefore, gain through marker-assisted selection (MAS) in this population for salt tolerance would be inefficient.Salt stress as one of the most important abiotic stress plays an important role in the yield reduction of crop p...