Toktam Taghavi

Genetic diversity of some wild almonds and related Prunus species revealed by SSR and EST-SSR molecular markers

Almond and its related wild species, which are widely distributed in Central and West Asia, have high genetic variation. This is an important source of genetic diversity for crop improvement. In this study a set of 32 SSR and 12 EST-SSR primer pairs were used to determine genetic diversity in 89 accessions of almond and other Prunus species. Most of the accessions (68) were collected from natural habitats of Iran. SSR primers amplified higher numbers of alleles than EST-SSR markers and discriminated genotypes more effectively. Results indicated high diversity among accessions. Observed heterozygosity (Ho) was 0.581. Nei’s index of diversity (He) and average number of alleles per locus (na) were 0.885 and 34, respectively. The mean value of polymorphism information content (PIC) was 0.874. The average Fst (F-statistics index) was 0.271 and the fixation index (Fis) was 0.151. Estimated variance among putative populations (AP) and individuals (AI) and within individuals (WI) were 5, 35, and 60%, respectively, which revealed that most of the variation was distributed among individuals rather than groups. Cultivated almonds were highly similar to P. fenzeliana, which is native to West Asia, supporting the importance of these regions in almond domestication. In the dendrogram of groups, minimum genetic distance was observed between Amygdalus and Orientalis groups from the Euamygdalus section. The Leptopus and Chameamygdalus sections were more distant from almonds than plums. The results also showed Dodecandra (Lycioides) series should be taxonomically classified closer to the section Euamygdalus.

A comparison of wild and cultivated strawberries for nitrogen uptake and reduction

The strawberry (Fragaria × ananassa) requires substantial amounts of nitrogen to produce reasonable yields. Wild strawberries (e.g. F. virginiana) grow in soils in the absence of supplemental nitrogen and may possess desirable genes, alleles or expression patterns that support efficient nitrogen uptake and assimilation. The F. virginiana accessions and cultivated materials were used to monitor the accumulation kinetics of five nitrate responsive genes (nitrate transporter, NRT1.1; nitrate reductase, NIA1; nitrite reductase, NiR; ferredoxin NADP reductase, FNR; and transketolase, TK) along with nitrate reductase activity. The results revealed expression patterns that were reminiscent of those observed in Arabidopsis. Wild strawberries exhibited higher transcript accumulation for all genes examined except the nitrate transporter, compared to cultivated materials. Nitrate reductase activity (NRA) did not change in roots but increased in leaves in response to nitrate. Most wild genotypes had higher NRA in aerial tissues compared to cultivated materials. Comparisons of enzyme activity to transcript accumulation kinetics suggest that available nitrate reductase is activated and not likely synthesized de novo, suggesting that some wild accessions may possess enhanced nitrogen assimilation mechanisms. These attributes may be useful to breeding programs in the design of elite plants that may make more efficient use of fertilizers.

Seed germination and seedling establishment of some wild almond species

Wild almond species are important genetic resources for resistance to unsuitable condition, especially drought stress. They have been used traditionally as rootstocks in some areas of Iran. So far, 21 wild almond species and 7 inter species hybrids have been identified in Iran. To study seed germination and seedling establishment of some of these species, three separate experiments were designed. In the first experiment, the application of gibberellic acid (GA 3 ) (0, 250, 500 and 750 ppm) for 24 h was studied on germination characteristics of four wild almond accessions after stratification at 5 ± 0.5°C in Perlite media. Germination percentage, index vigor and root initiation factors were different in almond accessions, but were not affected by hormonal treatments. In the second experiment, seeds of another six wild almond accessions were stratified to compare their germination ability. Germination percentage, index vigor and root initiation were different among accessions significantly. In the last experiment, the establishment and vigor of 14 accessions from eight almond species have been evaluated in plastic bags in outdoor conditions. Two ecotypes of Prunus spp. had the highest stem diameter and length at all growing stages. Keywords: Amygdalus, germination percentage, index vigor, root initiation, stem length, stem diameter.

Multiple Avenues to Gender in Strawberries

ABSTRACT Common strawberry cultivars are hermaphrodites, producing both anthers and pistils in their flowers. However, octoploid Fragaria species are trioecious and different genotypes can be female with pistillate flowers, hermaphrodites, or males with staminate flowers. One female selection, F. virginiana High Falls 22 and three hermaphrodite selections, N8688, RH23, and Montreal River 10 were hybridized with five June-bearing cultivars. Seedlings of each family were planted in Ontario and Michigan. Two F. chiloensis selections Pigeon Point (female) and FRA1267 (hermaphrodite), were hybridized with 14 F. virginiana selections. Seedlings from each family were planted in Ontario and Minnesota. In all progeny, the presence or absence of anthers was recorded and a subjective scale used to estimate the percentage of fruit set (1–10 representing 10% intervals). Also, FRA1267 was crossed with one F. × ananassa selection and the progeny intercrossed and grown in Ontario. In the sib-crosses gender was recorded. In two female parents, the female progeny had on average a higher fruit set than the hermaphrodite progeny. F. virginiana genotypes varied in their fruit set, which suggested that there are a number of alleles involved in the fertility of hermaphrodites. In crosses, FRA1267 produced 80% females when used as a female parent and 100% hermaphrodites when used as a male parent. It is thought that the trait is inherited cytoplasmically or that the F. chiloensis alleles involved are epistatic when F. virginiana or F. × ananassa is used as a male parent.

The performance of dayneutral strawberries differs between environments in Ontario

Abstract: The strawberry production season can be extended in Ontario if plantings are protected from adverse weather conditions. At present, dayneutral cultivars developed in California are used for production, but are not well adapted to Ontario conditions. The objectives of this study were to determine suitable dayneutral cultivars for production throughout Ontario and to investigate how they react to high tunnel environments. Two sets of trials were run. The first set, planted in 2005 and harvested in 2005-2006, compared six dayneutral cultivars of strawberries in four environments. The second set, planted in 2010 and harvested in 2010-2011, compared five dayneutral cultivars grown in four environments. For the summer crops, high tunnels had higher yields in the cooler environment at New Liskeard and low yields in the warmer environment of Cedar Springs, when compared with outside plantings. In the spring, this trend was reversed. ‘Seascape’ and ‘Tribute’ performed consistently in all environments. ‘Albion’ and ‘Monterey’, although medium yielding with lower winter survival, had large fruit size and exceptional fruit quality. ‘Portola’, had large fruits and performed well, so could be of interest to farmers in Ontario. All the European cultivars tested had medium to small berries.

Phylogenetic relationships among the first and second introns of selected Prunus S-RNase genes

Rahemi, A., Gradziel T.M., Chaparro J.X., Folta, K.M., Taghavi, T., Fatahi, R., Ebadi, A. and Hassani, D. 2015. Phylogenetic relationships among the first and second introns of selected Prunus S-RNase genes. Can. J. Plant Sci. 95: 1145-1154. To identify and evaluate self-incompatible alleles in almonds and related germplasm, DNA from 15 Prunus species was amplified using two degenerate consensus primer pairs flanking first and second S-locus introns (PaConsI-FD+EM-Pc1ConsRD and EM-Pc2ConsFD+EM-Pc3ConsRD). Twenty-eight amplified PCR products were analyzed by automated sequencer capillary electrophoresis. Sequenced fragments were aligned against available Prunus S-locus sequences in the National Center for Biotechnology Information and S-alleles identities were determined. The phylogenetic relationships between S-alleles in the germplasm studied were determined by the homology between their sequences and dendrograms were obtained for each primer pair. The Maximum Likelihood (homology) ranged from 84 to 100%. Most sequences were similar to cultivated almond (Prunus dulcis) or to the European wild almond (P. webbii). Twenty-six alleles for the first and the second introns were registered in the database in the GenBank. Two sequences of the first and second introns, which were taken from Prunus nairica and had similarity in GenBank, were registered in the database under a common sequence of the first and second intron. Analysis of phylogenetic relationships (dendrograms) among S-alleles from wild almond species as well as S-alleles cluster relations showed most pairs of alleles well supported by bootstrap.

Role of Natural Volatiles and Essential Oils in Extending Shelf Life and Controlling Postharvest Microorganisms of Small Fruits

Small fruits are a multi-billion dollar industry in the US, and are economically important in many other countries. However, they are perishable and susceptible to physiological disorders and biological damage. Food safety and fruit quality are the major concerns of the food chain from farm to consumer, especially with increasing regulations in recent years. At present, the industry depends on pesticides and fungicides to control food spoilage organisms. However, due to consumer concerns and increasing demand for safer produce, efforts are being made to identify eco-friendly compounds that can extend the shelf life of small fruits. Most volatiles and essential oils produced by plants are safe for humans and the environment, and lots of research has been conducted to test the in vitro efficacy of single-compound volatiles or multi-compound essential oils on various microorganisms. However, there are not many reports on their in vivo (in storage) and In situ (in the field) applications. In this review, we discuss the efficacy, minimum inhibitory concentrations, and mechanisms of action of volatiles and essential oils that control microorganisms (bacteria and fungi) on small fruits such as strawberries, raspberries, blueberries, blackberries, and grapes under the three conditions.

Vinegar and Iron Chelate Spray Affected Vegetative Growth and Yield of Grape cv. Thompson Seedless

In soils with high pH, iron is inactivated and bounded to the leaf apoplast developing leaf chlorosis. The inactive iron can be reduced artificially by lowering leaf apoplastic pH with spraying weak acid solutions, providing the symplast absorption of activated iron. The objective of this study was to determine the effect of vinegar spray, as an acidifying substance and iron chelate (Fe-EDTA) on iron nutrition and vegetative growth of grape vines (cv. Thompson Seedless) grown in high pH soils. Four years old grape vines of cv. Thompson Seedless which were grown in high pH soil (pH=8) were selected. Experimental design was a Randomized Complete Block Design (RCBD) with four spray treatments: 1) vinegar (0.8%), 2) iron chelate (0.2%), 3) combination of vinegar and iron chelate (0.8%, 0.2% respectively) and 4) distilled water (control). Vinegar treated plants had higher chlorophyll, active iron (Fe2+) and yield. Vinegar is a by product of grapes that can be easily produced by growers with very little cost and its application has effectively improved plant vegetative growth, yield and mitigated iron deficiency of “Thompson Seedless” grapes. Vinegar is very cheap compared to chelated iron. The vinegar spray has the potential to increases yield without increasing the cost for the growers, ensuring both profitability and sustainability of the production system.

Effects of silver nanoparticles (SNP) on Gerbera jamesonii cut flowers

Gerbera vase life is most often terminated by stem bending and breaking or petal wilting. Effects of vase solutions containing 1 mg L –1 silver nanoparticles with or without 6% sucrose on gerbera ‘deep purple’ vase life, relative fresh weight, relative solution uptake, stem bending or breaking, stem end discolouration and ethylene production by petals, stem ends and stem necks were evaluated. The combination of SNP plus 6% sucrose increased vase life by 8 days compared with the deionised water control. Petal wilting and stem break were decreased by SNP plus 6% sucrose compared to the control. SNP plus 6% sucrose treatment enhanced ethylene production by petals, stem ends and stem necks during vase life. However, there were no obvious adverse effects of this increased ethylene on vase life parameters. Overall, results suggest that 1 mg L –1 SNP plus 6% sucrose has commercial potential as a vase solution for cut gerbera flowers.