Farzad Aslani

Effects of Engineered Nanomaterials on Plants Growth: An Overview

Rapid development and wide applications of nanotechnology brought about a significant increment on the number of engineered nanomaterials (ENs) inevitably entering our living system. Plants comprise of a very important living component of the terrestrial ecosystem. Studies on the influence of engineered nanomaterials (carbon and metal/metal oxides based) on plant growth indicated that in the excess content, engineered nanomaterials influences seed germination. It assessed the shoot-to-root ratio and the growth of the seedlings. From the toxicological studies to date, certain types of engineered nanomaterials can be toxic once they are not bound to a substrate or if they are freely circulating in living systems. It is assumed that the different types of engineered nanomaterials affect the different routes, behavior, and the capability of the plants. Furthermore, different, or even opposing conclusions, have been drawn from most studies on the interactions between engineered nanomaterials with plants. Therefore, this paper comprehensively reviews the studies on the different types of engineered nanomaterials and their interactions with different plant species, including the phytotoxicity, uptakes, and translocation of engineered nanomaterials by the plant at the whole plant and cellular level.

Evaluation of antioxidant compounds, antioxidant activities, and mineral composition of 13 collected purslane (Portulaca oleracea L.) accessions.

The methanolic extracts of 13 accessions of purslane were analyzed for their total phenol content (TPC), total flavonoid contents (TFC), and total carotenoid contents (TCC) and antioxidant activity of extracts was screened using FRAP assay and DPPH radical scavenging methods. The TPC, TFC, and TCC ranged from 0.96 ± 0.04 to 9.12 ± 0.29 mg GAE/g DW, 0.13 ± 0.04 to 1.44 ± 0.08 mg RE/g DW, and 0.52 ± 0.06 to 5.64 ± 0.09 mg (β-carotene equivalent) BCE/g DW, respectively. The DPPH scavenging (IC50) activity varied between 2.52 ± 0.03 mg/mL and 3.29 ± 0.01 mg/mL and FRAP ranged from 7.39 ± 0.08 to 104.2 ± 6.34 μmol TE/g DW. Among all the measured micro- and macrominerals K content was the highest followed by N, Na, Ca, Mg, P, Fe, Zn, and Mn. The overall findings proved that ornamental purslane was richer in antioxidant properties, whereas common purslane possesses more mineral contents than ornamental ones.

Effects of salinity and salinity-induced augmented bioactive compounds in purslane (Portulaca oleracea L.) for possible economical use.

Dry matter (DM), total phenolics, flavonoids, carotenoid contents, and antioxidant activity of 12 purslane accessions were investigated against five levels of salinity (0, 8, 16, 24 and 32dSm(-1)). In untreated plants, the DM contents ranged between 8.0-23.4g/pot; total phenolics contents (TPC) between 0.96-9.12mgGAEg(-1)DW; total flavonoid contents (TFC) between 0.15-1.44mgREg(-1)DW; and total carotenoid contents (TCC) between 0.52BCEg(-1)DW. While FRAP activity ranged from 8.64-104.21mgTEg(-1)DW (about 12-fold) and DPPH activity between 2.50-3.30mgmL(-1) IC50 value. Different levels of salinity treatment resulted in 8-35% increases in TPC; about 35% increase in TFC; and 18-35% increases in FRAP activity. Purslane accessions Ac4, Ac5, Ac6 and Ac8 possessed potentials for salinity-induced augmented production of bioactive compounds which in turn can be harnessed for possible human health benefits.

Screening of Purslane (Portulaca oleracea L.) Accessions for High Salt Tolerance

Purslane (Portulaca oleracea L.) is an herbaceous leafy vegetable crop, comparatively more salt-tolerant than any other vegetables with high antioxidants, minerals, and vitamins. Salt-tolerant crop variety development is of importance due to inadequate cultivable land and escalating salinity together with population pressure. In this view a total of 25 purslane accessions were initially selected from 45 collected purslane accessions based on better growth performance and subjected to 5 different salinity levels, that is, 0.0, 10.0, 20.0, 30.0, and 40.0 dS m−1 NaCl. Plant height, number of leaves, number of flowers, and dry matter contents in salt treated purslane accessions were significantly reduced (P ≤ 0.05) and the enormity of reduction increased with increasing salinity stress. Based on dry matter yield reduction, among all 25 purslane accessions 2 accessions were graded as tolerant (Ac7 and Ac9), 6 accessions were moderately tolerant (Ac3, Ac5, Ac6, Ac10, Ac11, and Ac12), 5 accessions were moderately susceptible (Ac1, Ac2, Ac4, Ac8, and Ac13), and the remaining 12 accessions were susceptible to salinity stress and discarded from further study. The selected 13 purslane accessions could assist in the identification of superior genes for salt tolerance in purslane for improving its productivity and sustainable agricultural production.

Opportunities of marker‐assisted selection for rice fragrance through marker–trait association analysis of microsatellites and gene‐based markers

Developing fragrant rice through marker-assisted/aided selection (MAS) is an economical and profitable approach worldwide for the enrichment of an elite genetic background with a pleasant aroma. The PCR-based DNA markers that distinguish the alleles of major fragrance genes in rice have been synthesised to develop rice scent biofortification through MAS. Thus, the present study examined the aroma biofortification potential of these co-dominant markers in a germplasm panel of 189 F2 progeny developed from crosses between a non-aromatic variety (MR84) and a highly aromatic but low-yielding variety (MRQ74) to determine the most influential diagnostic markers for fragrance biofortification. The SSRs and functional DNA markers RM5633 (on chromosome 4), RM515, RM223, L06, NKSbad2, FMbadh2-E7, BADEX7-5, Aro7 and SCU015RM (on chromosome 8) were highly associated with the 2AP (2-acetyl-1-pyrroline) content across the population. The alleles traced via these markers were also in high linkage disequilibrium (R(2) > 0.70) and explained approximately 12.1, 27.05, 27.05, 27.05, 25.42, 25.42, 20.53, 20.43 and 20.18% of the total phenotypic variation observed for these biomarkers, respectively. F2 plants harbouring the favourable alleles of these effective markers produced higher levels of fragrance. Hence, these rice plants can be used as donor parents to increase the development of fragrance-biofortified tropical rice varieties adapted to growing conditions and consumer preferences, thus contributing to the global rice market.

Application of an Effective Statistical Technique for an Accurate and Powerful Mining of Quantitative Trait Loci for Rice Aroma Trait

When a phenotype of interest is associated with an external/internal covariate, covariate inclusion in quantitative trait loci (QTL) analyses can diminish residual variation and subsequently enhance the ability of QTL detection. In the in vitro synthesis of 2-acetyl-1-pyrroline (2AP), the main fragrance compound in rice, the thermal processing during the Maillard-type reaction between proline and carbohydrate reduction produces a roasted, popcorn-like aroma. Hence, for the first time, we included the proline amino acid, an important precursor of 2AP, as a covariate in our QTL mapping analyses to precisely explore the genetic factors affecting natural variation for rice scent. Consequently, two QTLs were traced on chromosomes 4 and 8. They explained from 20% to 49% of the total aroma phenotypic variance. Additionally, by saturating the interval harboring the major QTL using gene-based primers, a putative allele of fgr (major genetic determinant of fragrance) was mapped in the QTL on the 8th chromosome in the interval RM223-SCU015RM (1.63 cM). These loci supported previous studies of different accessions. Such QTLs can be widely used by breeders in crop improvement programs and for further fine mapping. Moreover, no previous studies and findings were found on simultaneous assessment of the relationship among 2AP, proline and fragrance QTLs. Therefore, our findings can help further our understanding of the metabolomic and genetic basis of 2AP biosynthesis in aromatic rice.

Allelopathic effect of methanol extracts from Tinospora tuberculata on selected crops and rice weeds

Herbicidal potential of aerial parts of Tinospora tuberculata on germination and seedling growth of seven test plant species, namely rice (Oryza sativa L.); two rice weeds, barnyardgrass (Echinochloa crus-galli L.) and weedy rice (O. sativa f. spontanea); and four vegetable crops, lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), carrot (Daucus carota L.), and cucumber (Cucumis sativus L.) were evaluated. Six concentrations of methanol extract (3.12, 6.25, 12.5, 25, 50, and 100 g L−1) were compared with the control (distilled water). The rate of seed germination and the radicle and hypocotyl length of 7-day-old test plant seedlings were reduced as the concentration of extracts increased compared to the control. Generally, the degree of toxicity of extracts derived from the leaves was more than the extracts derived from the stem. Cluster analysis and the concentrations required for 50% inhibition (defined as EC50) of all parameters showed that radicle growth was more suppressed than germination and hypocotyl growth. Lettuce and carrot were observed as the most sensitive plants while rice showed the highest tolerance to both extracts. Moreover, the dicot target plants were affected more severely than the monocots when treated with leaf extract. The chemical composition of the T. tuberculata methanolic extracts was analyzed by a GC–MS system. A total of 92 and 22 constituents (not previously identified) were found in the leaves and stem, respectively. The results showed that 17 of the 92 components in the leaves, as compared to 4 of 22 compounds in the stem, are known as toxic compounds. These results suggest that T. tuberculata contains a significant source of plant growth inhibitors with potential for the development of future natural herbicide.

Evaluation of some morphological traits associated with wheat yield under terminal drought stress

This study was carried out at the Seed and Plant Improvement Institute, Karaj (Iran) in 2007/2008 and 2008/2009 growing seasons to investigate the effects of two irrigation regimes (normal irrigation and no irrigation in post-anthesis growth stage) on grain yield of eight wheat cultivars (DM-81-6, DM-82-1, Bahar, DN-11, DN-7, Pishtaz, WS-82-9, and C-85-6). According to the results of variance analysis, it is clear that there is a significant difference among the testing cultivars in grain yield and yield components. It is a result of difference in grain yield reduction among genotypes under different irrigation regimes. DN-11 Genotype produced the highest grain yield under both irrigation regimes. The yield reduction of Bahar genotype was the highest under drought stress conditions. Based upon the result of stepwise regression analysis, the most important yield components were biological yield, harvest index, and 1000 grain yield. Key words:

Critical multifunctional role of the betaine aldehyde dehydrogenase gene in plants

ABSTRACT The betaine aldehyde dehydrogenase (BADH) gene plays a multifunctional role in plants. It is an important factor in fragrance production, abiotic stresses and antibiotic-free selection of transgenic plants. Molecular studies have presented a new picture of this critical factor involved in abiotic stress responses via the MAPK (mitogen-activated protein kinase) signalling pathway in numerous plants. Besides BADH, glycine betaine performs an important function in plant tolerance to environmental stresses. The presence of glycine betaine can help maintain the integrity of cell membranes against unexpected environmental stresses. BADH leads to production of glycine betaine through the oxidation of betaine aldehyde. Hence, BADH is considered a key regulator for glycine betaine formation. Consequently, by providing glycine betaine as a chemical interface, there is a critical role of BADH in enhancing the tolerance in an extensive range of plants subjected to different destructive abiotic stresses. The present article reviews the significant multifunctional role of the BADH gene in various plants, and also particularly argues how this important gene plays a responsive function to different destructive abiotic stresses, and its potential use in crop improvement using advanced technologies. Consequently, cloning of more BADH genes, specially from stress-tolerant plants, discovering their responsive signalling roles under environmental stresses, and validating such candidates for their potential are very helpful, and can open new windows to generate new stress-resistant crop cultivars.

Relationship between High Temperature and Formation of Chalkiness and Their Effects on Quality of Rice

Occurrence of chalkiness in rice is attributed to genetic and environmental factors, especially high temperature (HT). The HT induces heat stress, which in turn compromises many grain qualities, especially transparency. Chalkiness in rice is commonly studied together with other quality traits such as amylose content, gel consistency, and protein storage. In addition to the fundamental QTLs, some other QTLs have been identified which accelerate chalkiness occurrence under HT condition. In this review, some of the relatively stable chalkiness, amylose content, and gel consistency related QTLs have been presented well. Genetically, HT effect on chalkiness is explained by the location of certain chalkiness gene in the vicinity of high-temperature-responsive genes. With regard to stable QTL distribution and availability of potential material resources, there is still feasibility to find out novel stable QTLs related to chalkiness under HT condition. A better understanding of those achievements is essential to develop new rice varieties with a reduced chalky grain percentage. Therefore, we propose the pyramiding of relatively stable and nonallelic QTLs controlling low chalkiness endosperm into adaptable rice varieties as pragmatic approach to mitigate HT effect.