Quality assessment of flax advanced breeding lines varying in seed coat color and their potential use in the food and industrial applications.

BACKGROUND: With the increasing consumer awareness of the strong relationship between food and health, flax became a promising functional food due to its bioactive nutraceutical composition. Intra-specific crosses of eight contrasting flax genotypes were performed previously, and within segregating F6 progeny families, we investigated a close-up composition of phytochemicals derived from whole seeds. RESULTS: The considerable genetic variation among the flax F6 families suggested that intra-specific hybridization is essential in flax breeding to obtain and broaden genetic variability and largely affirmed the opportunity for selecting promising lines. Also, significant variations in the targeted metabolite contents and antioxidant properties were observed among brown and yellow-seeded families. Notably, brown-seeded families expressed the highest average values of saturated fatty acids, protein, fiber, tocopherol, phenolics, SDG, and SECO lignans. Yellow-seeded families represented the highest average content of unsaturated fatty acids and mucilage. The cultivation year significantly affects flaxseed's composition and functional properties, presumably due to temperature, humidity, and sunshine time differences. Interestingly, the seeds obtained in warmer conditions were more potent and had more chemical constituents. The favorable genetic correlations among all evaluated traits suggest the possibility of joint genetic selection for several nutritional and phytochemical characteristics in flax. The current study highlights the importance and utilization of 19 top families as their seeds and oil play imperative roles in the pharmaceuticals and food industries. The antioxidant capacity of the seeds showed that families 84B, 23B, 35Y, 95Y, 30B, 88B, and 78B serve as a natural source of dietary antioxidants beneficial to human health. To increase the oxidative stability of the flaxseed oil, the quality evaluation identified some families with low levels of linolenic acid. CONCLUSIONS: These findings are essential to improving flaxseed's nutritional quality and therapeutic properties through a bulk breeding program.

Characterization of 14 Triticum species for the NAM-B1 gene and its associated traits.

BACKGROUND: Wheat grain protein, zinc (Zn), and iron (Fe) content are important wheat qualities crucial for human nutrition and health worldwide. Increasing these three components simultaneously in wheat grains by a single gene came into the picture through NAM-B1 cloning. NAM-B1 gene and its association with the mentioned grain quality traits have been primarily studied in common and durum wheat and their progenitors T. dicoccum and T. dicoccoides. METHOD: In the present study, for the first time, 38 wheat accessions comprising ten hexaploids from five species and 28 tetraploids from nine species were evaluated in the field for two consecutive years. Additionally, the 582 first nucleotides of the NAM-B1 gene were examined. RESULT: The NAM-B1 gene was present in 21 tetraploids and five hexaploid accessions. Seven tetraploid accessions contained the wild-type allele (five T. dicoccum, one T. dicoccoides, and one T. ispahanicum) and fourteen the mutated allele with a 'T' insertion at position 11 in the open reading frame, causing a frameshift. In hexaploid wheat comprising the gene, only one accession of T. spelta contained the wild-type allele, and the rest resembled the insertion mutated type. In the two-year field experiment, eight accessions with the wild-type NAM-B1 allele had significantly higher protein, Zn and Fe grain content when compared to indel-type accessions. Additionally, these accessions exhibited a lower mean for seed-filling duration than all other accessions containing indel-type alleles. In terms of grain yield, 1,000-kernel weight, kernel diameter, and kernel length, T. dicoccum accessions having wild-type alleles were similar to the indel-type accessions over two years of evaluation. CONCLUSION: These findings further support the possibility of simultaneous improvement of wheat grain protein, Zn, and Fe content by a single gene crucial for human nutrition and health worldwide.

Water Stress and Seed Color Interacting to Impact Seed and Oil Yield, Protein, Mucilage, and Secoisolariciresinol Diglucoside Content in Cultivated Flax (Linum usitatissimum L.).

Flaxseed (Linum usitatissimum L.) is a plant with a wide range of medicinal, health, nutritional, and industrial uses. This study assessed the genetic potential of yellow and brown seeds in thirty F4 families under different water conditions concerning seed yield, oil, protein, fiber, mucilage, and lignans content. Water stress negatively affected seed and oil yield, while it positively affected mucilage, protein, lignans, and fiber content. The total mean comparison showed that under normal moisture conditions, seed yield (209.87 g/m2) and most quality traits, including oil (30.97%), secoisolariciresinol diglucoside (13.89 mg/g), amino acids such as arginine (1.17%) and histidine (1.95%), and mucilage (9.57 g/100 g) were higher in yellow-seeded genotypes than the brown ones ((188.78 g/m2), (30.10%), (11.66 mg/g), (0.62%), (1.87%), and (9.35 g/100 g), respectively). Under water stress conditions, brown-seeded genotypes had a higher amount of fiber (16.74%), seed yield (140.04 g/m2), protein (239.02 mg. g-1), methionine (5.04%), and secondary metabolites such as secoisolariciresinol diglucoside (17.09 mg/g), while their amounts in families with yellow seeds were 14.79%, 117.33 g/m2, 217.12 mg. g-1, 4.34%, and 13.98 mg/g, respectively. Based on the intended food goals, different seed color genotypes may be appropriate for cultivation under different moisture environments.

Drought adaptability of different subspecies of tetraploid wheat (Triticum turgidum) under contrasting moisture conditions: Association with solvent retention capacity and quality-related traits.

Few prior efforts have been made to investigate the genetic potential of different subspecies of Triticum turgidum for drought tolerance and their quality-related traits compared with common wheat (Triticum aestivum) and to identify the association among agronomic, micronutrients, and quality-related traits, especially under climate change conditions. In this research, grain quality, technological properties of flour, and some agronomic traits were studied in 33 wheat genotypes from six different subspecies of Triticum turgidum along with three cultivars of Triticum aestivum in the field, applying a well-watering (WW) and a water stress (WS) environment during two growing seasons. A high degree of variation was observed among genotypes for all evaluated traits, demonstrating that selection for these traits would be successful. Consequences of water stress were manifested as declined DM, GY, and LASRC; and significantly increased GPC, K+/Na+, WAF, WSRC, SuSRC, and SCSRC compared to the well-watering condition. The reductions in the unextractable polymeric protein fraction and glutenin-to-gliadin ratio indicated a poorer grain yield quality, despite higher protein content. This study showed that the early-maturing genotypes had higher water absorption and pentosan, and therefore were more suitable for bread baking. In contrast, late-maturing genotypes are ideal for cookie and cracker production. Two subspecies of T. turgidum ssp. durum and T. turgidum ssp. dicoccum with high micronutrient densities and quality-related traits, and T. turgidum ssp. oriental due to having high values of grain protein content can be used to improve the quality of T. aestivum through cross-breeding programs. Based on the association of different traits with SRC values and other quality-related traits and PCA results, contrasting genotypes can be used to develop mapping populations for genome studies of grain quality and functional properties of flour in future studies.

Association analysis revealed loci linked to post-drought recovery and traits related to persistence of smooth bromegrass (Bromus inermis).

Association analysis has been proven as a powerful tool for the genetic dissection of complex traits. This study was conducted to identify association of recovery, persistence, and summer dormancy with sequence related amplified polymorphism (SRAP) markers in 36 smooth bromegrass genotypes under two moisture conditions and find stable associations. In this study, a diverse panel of polycross-derived progenies of smooth bromegrass was phenotyped under normal and water deficit regimes for three consecutive years. Under water deficit, dry matter yield of cut 1 was approximately reduced by 36, 39, and 37% during 2013, 2014, and 2015, respectively, compared with the normal regime. For dry matter yield of cut 2, these reductions were approximately 38, 60, and 56% in the same three consecutive years relative to normal regime. Moreover, water deficit decreased the RY and PER of the genotypes by 35 and 28%, respectively. Thirty primer combinations were screened by polymerase chain reaction (PCR). From these, 541 polymorphic bands were developed and subjected to association analysis using the mixed linear model (MLM). Population structure analysis identified five main subpopulations possessing significant genetic differences. Association analysis identified 69 and 46 marker-trait associations under normal and water deficit regimes, respectively. Some of these markers were associated with more than one trait; which can be attributed to pleiotropic effects or tightly linked genes affecting several traits. In normal and water-deficit regimes, these markers could potentially be incorporated into marker-assisted selection and targeted trait introgression for the improvement of drought tolerance of smooth bromegrass.

Potentials of synthetic hexaploid wheats to improve drought tolerance.

Synthetic hexaploid wheat-derived lines (SHW-DL) offers new hope for breeders to restore genes lost during the evolutionary bottleneck. The study of adaptability, variation, and the possibility of selection in SHW-DL for drought tolerance is poorly understood in arid environments. The potential of 184 SHW-DL and their variation for agro-morphological traits were assessed under normal and water stress conditions for 2 years. The mean values of grain yield (YLD) varied from 683.9 g/m2 (water stress) to 992.1 g/m2 (normal conditions). Grain yield decreased by 64 and 71% under water stress in the two growing seasons. High genotypic variation was found for measured traits and drought tolerance. Heritability ranged from 19 (harvest index) to 47% (spike length), whereas grain yield indicated a moderate heritability (32%). Using the assessment of the interrelationship of traits, hectoliter (a quality trait) was correlated with drought tolerance and stability indices. Therefore, it can be considered as an important trait to select drought tolerant genotypes. In the following, the priority of yield components entering the regression model was different in two moisture conditions suggesting different strategies in indirect selection programs to improve yield. Spike m-2 and grain spike-1 indirectly and negatively affected yield through thousand-grain weight (TGW) under normal and water stress conditions, respectively. Furthermore, SHW-DL compared to ordinary wheat were significantly superior in terms of early maturity, dwarfing, yield, TGW, stem diameter, and harvest index. Overall, our findings suggest that SHW-DL are a valuable source for improving wheat yield and drought tolerance, and indirect selection might be possible to improve these complex traits.

Combined foliar application of Zn and Fe increases grain micronutrient concentrations and alleviates water stress across diverse wheat species and ploidal levels.

This study aimed to examine the reaction of several wheat species with different ploidy levels to foliar application of zinc (Zn) and iron (Fe) under different water regimes. Thirty-five wheat genotypes, including nineteen tetraploids from ten different species, ten hexaploids from five species, and six diploids from three species, were evaluated in the field over two moisture regimes with the following four treatments: control, foliar Zn application, foliar Fe application, and foliar Zn + Fe application. The experiments were conducted according to a split-plot scheme in a randomized complete block design with two replications in each moisture regime. Water stress negatively affected all measured traits, except grain Zn and Fe content. Combined foliar application of Zn + Fe significantly increased yield and alleviated yield reduction caused by water stress. Applying Zn and Fe significantly increased both micronutrient content in grains under both moisture conditions. Tetra and hexaploid species yielded nearly four times as much grain as unimproved diploid species and were less affected by water stress. All ploidy levels responded almost similarly to Zn and Fe treatments, with the combined application being as effective as each element separately. The highest yield increase in response to combined application of Zn + Fe under the two moisture conditions and the highest grain Zn content in response to Zn application under water stress was observed in hexaploid wheat. Combined foliar application of Zn and Fe increases grain Zn and Fe and alleviates water stress's adverse effects on all wheat ploidy levels, making biofortification cost-effective.

Revealing seed color variation and their possible association with yield and quality traits in a diversity panel of flax (Linum Usitatissimum L.).

Seed color is a vital quality determinant of flax, significant for consumers' acceptability, and determines the commercial values of seeds. Also, seed color as a phenotypic marker may be a convenient way to select the plants with desired traits. This study assessed a diversity panel representing 144 flax genotypes from diverse geographical origins for the existence of genetic variability for luminosity (L*) and chromaticity (a* and b*) seed color parameters, seed yield, and quality traits over two years. The genetic variance was significant for seed color parameters, demonstrating the presence of significant genetic variability, which provides a resource to objectively evaluate and select flax genotypes based on seed color according to the market demand. High heritability combined with the high genotypic coefficient of variation observed for seed yield, oil, and protein content suggested a better genetic gain upon selecting these traits. Seed yield, seed quality traits, and phenological traits showed significant negative correlation with L* and b* parameters and positive correlation with a* suggesting that the seeds' dark background and brown color can serve as marker characters to prescreen early-flowering, high-yielding and oil and protein-rich genotypes. Interestingly 48 brown-seeded genotypes were identified as early-flowering with short height, large seeds, high thousand seed weight, and capsule diameter. In addition, 34 genotypes were characterized by light-colored yellow seeds, large seeds, late-flowering with shorter height, and high branch numbers. Our results highlighted that North America and Australia-belonged genotypes were lighter yellow-seeded than the ones from other continents. Flax genotypes from South America and Asia were high-yielding, while genotypes from North America were low-yielding genotypes. Moreover, darker brown-seeded genotypes have prevailed in the South American continent.

Overexpression of Choline Oxidase Gene in Three Filial Generations of Rice Transgenic Lines.

Background: Glycinebetaine (GB) accumulation in many halophytic plants, animals, and microorganisms confers abiotic stress tolerance to salinity, drought, and extreme temperatures. Although there are a few genetic and biochemical pathways to synthesize GB, but isolation of a single gene Choline Oxidase (codA) from Arthrobacter spp. have opened a new hatch to engineer the susceptible plants. Objectives: The effects of overexpressed codA gene, through multiple copy insertion and GB accumulation on salinity tolerance in rice were studied. Materials and Methods: Seed-derived embryogenic calli of 'Tarom Molaie' cultivar were targeted with two plasmids pChlCOD and pCytCOD both harboring the codA gene using the biolistic mediated transformation. The regenerated T0 plants were screened by PCR analysis. A line containing three copies of codA gene and harboring pChlCOD and pCytCOD was identified by Southern blot analysis. The expression of codA gene in this transgenic line was then confirmed by RT-PCR. The Mendelian segregation pattern of the inserted sequences was accomplished by the progeny test using PCR. The effects of overexpression of codA on salinity tolerance were evaluated at germination and seedling stage using T2-pChl transgenic line and control seeds in the presence of 0, 100, 200, and 300 mM NaCl. Finally, leaf growth dynamics of T2-pChlCOD transgenic line and control line under hydroponic conditions in the presence of 0, 40, 80, and 120 mM NaCl were assessed. Results: The seed germination experiment results showed that the transformed seeds had a higher germination rate than the controls under all salinity treatments. But also, the leaf growth dynamics showed that the control plants had a more favorable leaf growth dynamic in all of the treatments. Although, the transgenic lines (T0, T1 and T2) exhibited lower performance than the wild type, the transgenic line varied for GB and choline contents and increasing codA gene copy number led to increased GB content. Conclusion: In a salinity sensitive crop such as rice, GB may not significantly contribute to the plant protection against salt stress. Also, insufficiency of choline resources as GB precursor might have affected the overall growth ability of the transgenic line and resulted in decreased leaf growth dynamics.

Water stress intensified the relation of seed color with lignan content and seed yield components in flax (Linum usitatissimum L.).

This study aimed to investigate the effect of yellow and brown seed coat color of flax on lignan content, seed yield, and yield components under two contrasting environments of non-stress and water stress conditions. The water stress environment intensified the discrimination between the two seed color groups as the yellow seeded families had lower values for seed yield components under the water stress. Heritability and the genetic advance for seed yield were significantly higher in brown-seeded families than those of yellow-seeded ones at water stress conditions. Secoisolariciresinol diglucoside (SDG) as the chief lignan in flaxseed was more abundant in yellow-seeded families under the non-stress environment but under water stress conditions, it increased in brown seeded families and exceeded from yellow ones. Considering that the brown and yellow seed color families were full sibs and shared a similar genetic background but differed in seed color, it is concluded that a considerable interaction exists between the flax seed color and moisture stress concerning its effect on seed yield and yield components and also the seed SDG content. Brown-seeded genotypes are probably preferred for cultivation under water stress conditions for better exploitation of flax agronomic and nutritional potentials.

Evolution of Carthamus species revealed through sequence analyses of the fad2 gene family.

The diversity of 11 fatty acid desaturase (fad2) genes has not been investigated between cultivated and wild species in the Carthamus genus. In this study, 17 C. tinctorius accessions and 28 accessions from other Carthamus species were subjected to sequence analyses of this fad2 gene family. Results showed that among these genes, fad2-1 had a major role in the conversion of oleic acid to linoleic acid. Grouping of all studied wild polyploid species and the wild diploid C. leucocaulos suggested that C. lanatus transferred its fad2-1 gene to C. turkestanicus and C. lanatus. A phylogenetic tree based on fad2-1 gene sequences also showed that C. palaestinus and C. oxyacanthus grouped with C. tinctorius individuals, suggesting that C. tinctorius is closely related to both wild species. A one base pair deletion at position 604 in the fad2-1 gene coding region correlated with high levels of oleic acid content in five mutant phenotypes of the evaluated C. tinctorius accessions. Grouping of fad2-1 and fad2-8 (Ctfad2-10) indicated that both of these genes are involved in oleate desaturases activity. The fad2-3 (Ctfad2-3) and Ctfad2-4 had the highest sequence similarity among the other fad2 genes, indicating the conservative nature of these two genes among all the studied species. Our results suggest that C. lanatus is the likely progenitor of C. turkestanicus and C. creticus (Synonym C. baeticus). Also, C. palaestinus is genetically closer to C. tinctorius but the involvement of C. oxyacanthus cannot be excluded and, this requires further investigation.

Proteomics analysis of Medicago truncatula response to infection by the phytopathogenic bacterium Ralstonia solanacearum points to jasmonate and salicylate defence pathways.

The infection of the model legume Medicago truncatula with Ralstonia solanacearum GMI1000 gives rise to bacterial wilt disease via colonisation of roots. The root and leaf responses to early infection (1 and 3 days post infection) were characterised to investigate the molecular mechanisms of plant resistance or susceptibility. A proteomics approach based on pools of susceptible and resistant recombinant inbred lines was used to specifically target the mechanisms for tolerance. Differential abundances were evidenced for proteins involved in defence (e.g., PR5, PR10, or Kunitz protease inhibitors) and signalling pathways (such as cyclophilin). R. solanacearum inoculation modifies expression levels of those genes, either in both genotypes (AOS1, LOX4, and proteinase inhibitors) or specifically in the resistant line (PR proteins). Exogenous application of salicylic acid (SA) enhanced tolerance to the bacteria, whereas methyl jasmonate (MeJA) enhanced short-term tolerance then promoted disease in the susceptible ecotype, suggesting that they may mediate defence responses. Conversely, proteomics-identified genes were also shown to be SA or MeJA responsive. This is the first description of differential response to R. solanacearum in M. truncatula. Our results suggest that root basal defence is activated at 1 dpi, together with the JA pathway. Specific resistance is then evidenced at three dpi, with the up-regulation of SA-dependent PR proteins.

Assessment of the Genetic Diversity Among Potato Cultivars from Different Geographical Areas Using the Genomic and EST Microsatellites.

BACKGROUND: Potato has a narrow genetic base which is due to its development, as it takes its genetic root from a few genotypes originated from South America. OBJECTIVES: The objective of this study was to assess the genetic relationships among potato (Solanum tuberosum L.) genotypes originated from different geographical regions. MATERIALS AND METHODS: This study has rendered 25 useful SSRs and EST-SSRs that were located in pre-existing genetic maps, fingerprinted in a collection of the 47 potato genotypes from America, Europe and Iran. RESULTS: The number of alleles per locus ranged from 2 to 9 with an average of 6.22 alleles per locus. UPGMA dendrogram, constructed from microsatellite data based on Jaccard similarity coefficient slightly clustered the American and European potatoes according to their geographical distribution. Iranian genotype, "Istanbuli", joined to a group with American genotype. The results indicated that American genotypes show the highest expected heterozygosity compared to the European genotype. This result was expected due to the narrow genetic base of European potatoes considering their origin from a limited number of introductions. CONCLUSIONS: It could be concluded that SSR is an appropriate marker for evaluating genetic diversity within and among potatoes from different geographical regions.

Protein engineering of Bacillus thermocatenulatus lipase via deletion of the α5 helix.

Lipases from Bacillus thermocatenulatus are a member of superfamily of α/ß hydrolase, but there are structural differences between them. In this work, we focused on the α5 helix of B. thermocatenulatus lipase (BTL2) which is absent in canonical α/ß hydrolase fold. In silico study showed that the α5 helix is a region that causes disorder in BTL2 protein. So, the α5 helix (residues 131 to 150) has been deleted from the B. thermocatenulatus lipase gene (BTL2) and the remain (Δα5-BTL2) has been expressed in Pichia pastoris yeast. The α5 deletion results in increase of enzyme-specific activity in the presence of tributyrin, tricaproin, tricaprylin, tricaprin, trilaurin, and olive oil (C18) substrates by 1.4-, 1.7-, 2.0-, 1.2-, 1.75-, and 1.95-fold, respectively. Also, deletion leads to increase in enzyme activity in different temperatures and pHs, whereas it did not significantly affect on enzyme activity in the presence of organic solvents, metal ions, and detergents.

Discrimination between two rice metallothionein isoforms belonging to type 1 and type 4 in metal-binding ability.

Metallothioneins (MTs) are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. Plants have several MT isoforms, which are classified into four types based on the arrangement of Cys residues. In this study, two rice (Oryza sativa) MT isoforms, OsMTI-1b and OsMTII-1a from type 1 and type 4, respectively, were heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST). Transformed cells expressing GST-OsMTI-1b showed increased tolerance to Ni(2+) , Cd(2+) , and Zn(2+) and accumulated more metal ions compared with cells expressing GST alone. However, heterologous expression of GST-OsMTII-1a had no significant effects on metal tolerance or ion accumulation. The UV absorption spectra and competitive reactions of in vitro Cd-incubated proteins with 5-5'-dithiobis(2-nitrobenzoic) acid revealed that GST-OsMTI-1b, but not GST-OsMTII-1a, is able to form Cd-thiolate clusters. Furthermore, heterologous expression of both GST-OsMTI-1b and GST-OsMTII-1a conferred H2 O2 tolerance to E. coli cells. Taken together, the results presented here show that two different rice MT isoforms belonging to type 1 and type 4 differ in Ni(2+) , Cd(2+) , and Zn(2+) binding abilities, but they may have overlapping function in protection of cells against oxidative stress.

Heterologous expression and metal-binding characterization of a type 1 metallothionein isoform (OsMTI-1b) from rice (Oryza sativa).

Metallothioneins (MTs) are ubiquitous, low molecular mass and cysteine-rich proteins that play important roles in maintaining intracellular metal homeostasis, eliminating metal toxification and protecting the cells against oxidative damages. MTs are able to bind metal ions through the thiol groups of their cysteine residues. Plants have several MT isoforms which are classified into four types based on the arrangement of cysteine residues. In the present study, a rice (Oryza sativa) gene encoding type 1 MT isoform, OsMTI-1b, was inserted in vector pET41a and overexpressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST). The recombinant protein GST-OsMTI-1b was purified using affinity chromatography and its ability to bind with Ni(2+), Cd(2+), Zn(2+) and Cu(2+) ions was analyzed. The results demonstrated that this isoform has ability to bind Ni(2+), Cd(2+) and Zn(2+) ions in vitro, whereas it has no substantial ability to bind Cu(2+) ions. From competitive reaction with 5,5'-dithiobis(2-nitrobenzoic acid), DTNB, the affinity of metal ions for recombinant form of GST-OsMTI-1b was as follows: Ni(2+)/Cd(2+) > Zn(2+) > Cu(2+).

Molecular evidence for Neotyphodium fungal endophyte variation and specificity within host grass species.

Host specificity of Neotyphodium species symbiotic with three grass species, Festuca arundinacea, Festuca pratensis and Lolium perenne, was studied based on comparisons of amplified fragment length polymorphisms (AFLP) between hosts and their corresponding endophytes. Endophytic fungi were isolated from 24 accessions of host plants. Neotyphodium identity was determined based on morphological characteristics observed in cultures and polymerase chain reaction analysis using specific primers. The results of AFLP data analysis revealed high genetic variation in plant and fungal endophyte species. Plant AFLP genotypes from different species clustered in three distinctive groups, congruent with species. A cluster analysis of AFLP data grouped endophytic isolates according to their host species and secondarily according to their host geographic distribution. The result of the AMOVA on AFLP data accounted for a large and significant proportion of genetic variation due to differences among plant and endophyte species. Phylogenetic groups of isolates corresponded to their respective host genotypes based on maximum parsimony phylograms. Comparisons of the two phylograms illustrated a significant congruence between nodes and branches of host and endophyte clades. These results strongly suggest host specificity of Neotyphodium fungal endophytes with their geographically distant host grasses within each species.

Effect of endophytic fungi on cadmium tolerance and bioaccumulation by Festuca arundinacea and Festuca pratensis.

Endophytic fungi are a group of fungi that live asymptomatically inside plant tissue. These fungi may increase host plant tolerance to biotic and abiotic stresses. The effect of Neotyphodium endophytes in two grass species (Festuca arundinacea and Festuca pratensis) on cadmium (Cd) tolerance, accumulation and translocation has been our main objective. The plants were grown in a hydroponic system under different Cd concentrations (0, 5, 10, and 20 mg L(-1)) for 6 weeks. They were also grown in soil spiked with different concentrations of Cd (0, 10, 20, and 40 mg kg(-1)) for 2 months. The results from all Cd treatments showed higher biomass production (12-24%) and higher potential to accumulate Cd in roots (6-16%) and shoots (6-20%) of endophyte-infected plants than endophyte-free plants. Cadmium accumulation by plants indicated that the grasses were capable of Cd hyperaccumulation, a property that was augmented after endophyte infection. Maximum photochemical efficiency of photosystem II (Fv/Fm) revealed that Cd stress was significantly reduced in endophyte-infected plants compared to non-infected ones.

Widespread occurrence of Neotyphodium-like endophyte in populations of Bromus tomentellus Boiss. in Iran.

Neotyphodium species occur as endophytic fungi in cool-season grasses around the world. The beneficial aspects of grass-Neotyphodium associations have provoked researchers to look for a novel association in plant species where this symbiotum has not been reported. We surveyed Russian bromegrass (Bromus tomentellus Boiss.) accessions from a germplasm collection for the presence of Neotyphodium spp. fungi and determined levels of endophyte infection in B. tomentellus populations in native rangelands of Iran. Among 50 collected accessions, symbiotic fungi were detected in 45 accessions without any symptoms of choke disease on host plants. In culture medium, fast-growing endophytes appeared from seeds after 7-14 days. Plants grown from seed collections were 80-100% infected. Based on morphological characteristics and PCR analysis, we concluded that this fungus is a member of the Neotyphodium group of endophytic fungi. Lack of apparent toxicity to grazing animals suggests a place for endophyte-infected B. tomentellus in rangeland renovation, providing this infected grass exhibits increased tolerance to abiotic stresses.