Natural incidence of tomato viruses in the North of Iran

A survey was conducted in Qazvin province in the North of Iran, to determine the incidence of tomato viruses including: Tobacco mosaic virus (TMV), Tomato yellow leaf curl virus (TYLCV), Tomato chlorotic spot virus (TCSV), Tomato bushy stunt virus (TBSV), Tomato spotted wilt virus (TSWV), Tomato ring spot virus (ToRSV), Tomato aspermy virus (TAV), Potato virus Y (PVY), Beet curly top virus (BCTV), and Cucumber mosaic virus (CMV). A total of 742 tomato symptomatic samples were collected during the summer of 2007 in five regions of Qazvin province (Qazvin, Takestan, Boeen-Zahra, Alborz and Abiyek) and tested by enzyme-linked immunosorbent assay (ELISA). TSWV was detected in Alborz (4.4 %) and Abiyek (3.57%) regions but TMV and CMV were detected in all five regions. The greatest and least incidence of tomato viruses were recorded in Alborz (40.7 %) and Takestan (11.1 %), respectively. The presence of these viruses was also evaluated in the weed hosts as natural sources of plant viruses. The greatest and least incidence of tomato viruses in weed hosts were recorded in Boeen-Zahra (25.6 %) and Qazvin (12.8 %), respectively. TSWV was not detected in weeds. Transmission tests demonstrated that Thrips tabaci acts as TSWV carrier and Myzus persicae and Aphis gossypii were CMV carriers. Seed transmission tests were positive for TMV (13 tomato seedlings from 100 seedlings), but no TSWV transmission was observed through the seeds of infected tomato fruits

Identification of novel plant architecture mutants in barley

In grasses, biomass and grain production are affected by plant architecture traits such as tiller number, leaf size and orientation. Thus, knowledge regarding their genetic basis is a prerequisite for developing new improved varieties. Mutant screens represent a powerful approach to identify genetic factors underpinning these traits: the HorTILLUS population, obtained by mutagenesis of spring two-row cultivar Sebastian, is a valuable resource for this purpose in barley. In this study, 20 mutant families from the HorTILLUS population were selected and evaluated for tiller number, leaf angle and a range of other plant architecture and agronomic traits using an unreplicated field design with Sebastian as a check cultivar. Principal Component Analysis revealed strong relationships among number of tillers, upper canopy leaf angle, biomass and yield-related traits. Comparison to the Sebastian background revealed that most mutants significantly differed from the wild-type for multiple traits, including two mutants with more erect leaves and four mutants with increased tiller number in at least one phenological stage. Heatmap clustering identified two main groups: the first containing the two erect mutants and the second containing Sebastian and the high-tillering mutants. Among the high-tillering mutants, two showed significantly higher biomass and grain yield per plant compared to Sebastian. The selected mutants represent promising materials for the identification of genetic factors controlling tillering and leaf angle in barley

Development of IRAP- and REMAP-derived SCAR markers for marker-assisted selection of the strip rust resistance gene Yr15 derived from wild emmer wheat

Stripe rust (Pucinia striformis f.sp. tritici) is one of the most important fungal diseases of wheat, found on all continents and in over 60 countries. Wild emmer wheat, Triticum dicoccoides, which is the tetraploid progenitor of durum wheat, is a valuable source of novel stripe rust resistance genes for wheat breeding. T. dicoccoides G25 accession carries Yr15, a gene on chromosome arm 1BS. Yr15 confers resistance to all known stripe rust isolates; it is also effective in introgressed durum and bread wheat. Retrotransposons generate polymorphic insertions, which can be scored as Mendelian markers with techniques including REMAP and IRAP. Six REMAP and IRAP-derived SCAR markers were developed using 1256 F2 plants derived from crosses of the susceptible T. durum accession D447 with its resistant BC3F9 and BC3F10 (B9 and B10) near isogenic lines, which carried Yr15 introgressed from G25. The nearest markers segregated 0.1 cM proximally and 1.1 cM distally to Yr15. These markers were also mapped and validated at the same position in another independent 500 F2 plants derived from crosses of B9 and B10 with the susceptible cultivar Langdon. SCAR270 and SCAR790, surrounding Yr15 at an interval of 1.2 cM, were found to be reliable and robust co-dominant markers in a wide range of wheat lines and cultivars with and without Yr15. These markers are useful tags in marker-assisted wheat breeding programs aiming to incorporate Yr15 into elite wheat lines and cultivars for durable and broad-spectrum resistance against stripe rust.Peer reviewe

Genetic diversity of Aegilops tauschii accessions and its relationship with tetraploid and hexaploid wheat using retrotransposon-based molecular markers

Aegilops is known as the ancestor species of wheat and has a major role in the evolution of wheat. Considering the importance of this species and the fact that Iran is the center of the distribution, fifteen IRAP and REMAP markers were used to evaluate the genetic diversity of Ae. tauschii accessions from different regions of Iran and its relationship with Triticum durum and Triticum aestivum. A high level of polymorphism (99%) was observed for both retrotransposon markers. Polymorphism information content, the effective number of alleles (Ne), Nei’s genetic diversity (H), and Shannon’s information index (I) for IRAP markers were more than REMAP markers. The most genetic diversity was detected in Ae. tauschii accessions. The cluster analysis separated the accessions into three distinct groups. Ae. tauschii accessions from Golestan province grouped in the same cluster with T. aestivum genotypes, indicating that these accessions are probably more like to the progenitor of the bread wheat D genome. Our results revealed that retrotransposon-based molecular markers could be used as the appropriate and reliable marker system to evaluate genetic diversity and relationship in Triticum and Aegilops accessions

Assessment of genetic diversity in tomato landraces using ISSR markers

Tomato is one of the most economically important vegetable crops in many parts of the world. Turkey and Iran are the main producers of tomatoes in the world. The objective of this study was to assess the genetic variation of 93 tomato landraces from East Anatolian region of Turkey and North-West of Iran, along with three commercial cultivars using 14 ISSR primers. The percentage of polymorphic loci (PPL) for all primers was 100%. The mean of expected heterozygosity (He) for the primers varied from 0.153 (UBC808) to 0.30 (UBC848). The dendrogram placed the landraces and commercial cultivars into nine groups. The genotypes originating from the same region, often located in the same group or two adjacent groups. The highest likelihood of the data was obtained when population were located into 2 sub-populations (K = 2). These sub-populations had Fst value of 0.16 and 0.21

IRAP and REMAP-based assessment of genetic diversity in chickpea collection from Iran

Retrotransposons (RTN) make a significant contribution to the size, organization and genetic diversity of their host genomes. Several RTN families have been identified in chickpea (Cicer arietinum L.) and other closely related species. In the current research, integration activity and insertional polymorphism of the RTNs CARE1, Tms1Ret1, TPS and LORE were studied in 64 chickpea accessions collected in Iran using inter retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) techniques. Results indicated that all RTNs studied, are transpositionally active in chickpea genome and amplified scorable and polymorphic banding pattern. Among the RTN families used, the highest percentage of polymorphic loci (PPL) was produced by TPS family (81.82%). Totally, 129 loci were amplified using 18 IRAP and REMAP primers which 83 (64.34%) were polymorphic. The Dice genetic similarity coefficients among accessions ranged from 0.84 (accessions Tj48 and Ba4) to 0.98 (accessions Ka30 and Urm61), averaging 0.93. The parameters of expected heterozygosity (He), Shannon’s information index (I) and number of effective alleles (Ne) were the highest for Urmia accessions. Cluster analysis based on UPGMA algorithm and Dice similarity coefficient categorized the 64 accessions in 7 main groups. The mean Fst values of all groups except for groups IV and VII, were lower than 0.20, demonstrating no clear differentiation among the groups, no genetic structure of the studied chickpea collection and probably occurrences of gene flow among the origins. In conclusion, although RTN-based markers were able to differentiate the chickpea accessions but the measured relative genetic similarity among accessions were not correlated with geographical distances between places of their origins

Genetic Mapping of Quantitative Trait Loci for Yield-Affecting Traits in a Barley Doubled Haploid Population Derived from Clipper × Sahara 3771

Many traits play essential roles in determining crop yield. Wide variation for morphological traits exists in Hordeum vulgare L., but the genetic basis of this morphological variation is largely unknown. To understand genetic basis controlling morphological traits affecting yield, a barley doubled haploid population (146 individuals) derived from Clipper × Sahara 3771 was used to map chromosome regions underlying days to awn appearance, plant height, fertile spike number, flag leaf length, spike length, harvest index, seed number per plant, thousands kernel weight, and grain yield. Twenty-seven QTLs for nine traits were mapped to the barley genome that described 3–69% of phenotypic variations; and some genomic regions harbor a given QTL for more than one trait. Out of 27 QTLs identified, 19 QTLs were novel. Chromosomal regions on 1H, 2H, 4H, and 6H associated with seed grain yield, and chromosome regions on 2H and 6H had major effects on grain yield (GY). One major QTL for seed number per plant was flanked by marker VRS1-KSUF15 on chromosome 2H. This QTL was also associated with GY. Some loci controlling thousands kernel weight (TKW), fertile spike number (FSN), and GY were the same. The major grain yield QTL detected on linkage PSR167 co-localized with TAM10. Two major QTLs controlling TKW and FSN were also mapped at this locus. Eight QTLs on chromosomes 1H, 2H, 3H, 4H, 5H, 6H, and 7H consistently affected spike characteristics. One major QTL (ANIONT1A-TACMD) on 4H affected both spike length (SL) and spike number explained 9 and 5% of the variation of SL and FSN, respectively. In conclusion, this study could cast some light on the genetic basis of the studied pivotal traits. Moreover, fine mapping of the identified major effect markers may facilitate the application of molecular markers in barley breeding programs

Intraspecific divergence in essential oil content, composition and genes expression patterns of monoterpene synthesis in Origanum vulgare subsp. vulgare and subsp. gracile under salinity stress

Abstract Background Oregano (Origanum vulgare L.), one of the important medicinal plants in the world, has valuable pharmacological compounds with antimicrobial, antiviral, antioxidant, anti-inflammatory, antispasmodic, antiurolithic, antiproliferative and neuroprotective activities. Phenolic monoterpenes such as thymol and carvacrol with many medical importance are found in Oregano essential oil. The biosynthesis of these compounds is carried out through the methyl erythritol-4 phosphate (MEP) pathway. Environmental stresses such as salinity might improve the secondary metabolites in medicinal plants. The influence of salinity stress (0 (control), 25, 50 and 100 mM NaCl) on the essential oil content, composition and expression of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), γ-terpinene synthase (Ovtps2) and cytochrome P450 monooxygenases (CYP71D180) genes involved in thymol and carvacrol biosynthesis, was investigated in two oregano subspecies (vulgare and gracile). Results Essential oil content was increased at low NaCl concentration (25 mM) compared with non-stress conditions, whereas it was decreased as salinity stress intensified (50 and 100 mM). Essential oil content was significantly higher in subsp. gracile than subsp. vulgare. The highest (0.20 mL pot−1) and lowest (0.06 mL pot−1) amount of essential oil yield was obtained in subsp. gracile at 25 and 100 mM NaCl, respectively. The content of carvacrol, as the main component of essential oil, decreased with increasing salinity level in subsp. gracile, but increased in subsp. vulgare. The highest expression of DXR, Ovtps2 and CYP71D180 genes was observed at 50 mM NaCl in subsp. vulgare. While, in subsp. gracile, the expression of the mentioned genes decreased with increasing salinity levels. A positive correlation was obtained between the expression of DXR, Ovtps2 and CYP71D180 genes with carvacrol content in both subspecies. On the other hand, a negative correlation was found between the expression of CYP71D180 and carvacrol content in subsp. gracile. Conclusions The findings of this study demonstrated that both oregano subspecies can tolerate NaCl salinity up to 50 mM without significant reduction in essential oil yield. Also, moderate salinity stress (50 mM NaCl) in subsp. vulgare might increase the carvacrol content partly via increment the expression levels of DXR, Ovtps2 and CYP71D180 genes

Genetic analysis of partial resistance to basal stem rot (Sclerotinia sclerotiorum) in sunflower

Basal stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is one of the major diseases of sunflower (Helianthus annuus L.) in the world. Quantitative trait loci (QTLs) implicated in partial resistance to basal stem rot disease were identified using 99 recombinant inbred lines (RILs) from the cross between sunflower parental lines PAC2 and RHA266. The study was undertaken in a completely randomized design with three replications under controlled conditions. The RILs and their parental lines were inoculated with a moderately aggressive isolate of S. sclerotiorum (SSKH41). Resistance to disease was evaluated by measuring the percentage of necrosis area three days after inoculation. QTLs were mapped using an updated high-density SSR and SNP linkage map. ANOVA showed significant differences among sunflower lines for resistance to basal stem rot (P <= 0.05). The frequency distribution of lines for susceptibility to disease showed a continuous pattern. Composite interval mapping analysis revealed 5 QTLs for percentage of necrotic area, localized on linkage groups 1, 3, 8, 10 and 17. The sign of additive effect was positive in 5 QTLs, suggesting that the additive allele for partial resistance to basal stem rot came from the paternal line (RHA266). The phenotypic variance explained by QTLs (R 2) ranged from 0.5 to 3.16%. Identified genes (HUCL02246_1, GST and POD), and SSR markers (ORS338, and SSL3) encompassing the QTLs for partial resistance to basal stem rot could be good candidates for marker assisted selection