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Drought stress is one of the main constraints limiting worldwide crop production. Arbuscular mycorrhizae (AM) and plant growth-promoting bacteria (PGPB) such as Azotobacter chroococcum and Azospirillium lipofrum have been shown to alleviate drought stress effects. Therefore, the interaction effect of AM fungi [Glomus mosseae, G. etunicatum, and a mix of these (G. mix), and PGPB bacteria (Azotobacter chroococcum + Azospirillium lipofrum)] was investigated in 1-year-old walnut seedlings (cv. Chandler) under normal and drought stress conditions. Drought stress reduced growth (plant height, root length, number of leaves, and fresh weight) and leaf nutrient content (N, P, and Zn) significantly of walnut plants. In contrast, proline, total soluble sugar, starch peroxidase enzyme activity, and total phenolic content of walnut leaves increased under this stress. Application of fungi or bacteria, and especially their simultaneous use, alleviated the negative effects of drought stress on walnut seedlings. AM fungi and PGPB increased significantly the content of some metabolites, including total phenolic content, proline level, peroxidase activity, total soluble sugar, and starch content as well as peroxidase enzyme activity. This led to an increase in walnut plant growth under the drought stress condition. Among AM fungi, G. etunicatum was more effective in reducing drought stress symptoms than either G. mosseae or the G. mix of fungi. In conclusion, use of G. etunicatum, along with PGPB, can reduce negative effects of drought stress on walnut seedlings.

Garden cress (Lepidium sativum L., Brassicaceae) is one of the most popular leafy vegetables which is widely used, and has also various medicinal properties and industrial usage. Small and very delicate leaves of this short period and fast growing species cause lots of crop losses along production to consumption; so it was supposed that increase in thickness and size of the leaves via induction of polyploidy possibly will improve post-harvest quality. Primary trial proved that seed treatments, via immersion of dry and wet seeds in different concentrations and durations of colchicine, were completely ineffective. Thereafter dropping method was conducted on apical bud of cotyledon and two true leaf stages with different concentrations of colchicine (0, 0.05, 0.1, 0.2, 0.5 and 0.75% w/v). Treatment on cotyledon stage was not fruitful because of sensitivity to colchicine and dying of small seedlings; but apical bud treatment in two true leaf stage resulted in inducing some polyploid plants. The best result was obtained by 0.5% colchicine concentration, inducing 9.33% tetraploid plants. Chromosome counting and flowcytometric analysis of morphologically putative plants confirmed chromosome doubling in garden cress from 2n = 2x = 16 to 2n = 4x = 32. Tetraploid plants comparing diploid ones specified by increasing in leaf size and thickness, stem diameter, stomata size, number of chloroplasts in stomata guard cells, seed weight and on the contrary, decreasing in stomata count and height of plants, percentage of seed germination and also germination rate. In this research, we have tested various methods and different levels of colchicine for the polyploidy induction in garden cress, and the results of polyploidy induction have been studied.

GABA (gamma-aminobutyric acid) and melatonin are endogenous compounds that enhance plant responses to abiotic stresses. The response of Vicia faba to different stressors (salinity (NaCl), poly ethylene glycol (PEG), and sulfur dioxide (SO2)) was studied after priming with sole application of GABA and melatonin or their co-application (GABA + melatonin). Both melatonin and GABA and their co-application increased leaf area, number of flowers, shoot dry and fresh weight, and total biomass. Plants treated with GABA, melatonin, and GABA + melatonin developed larger stomata with wider aperture compared to the stomata of control plants. The functionality of the photosynthetic system was improved in primed plants. To investigate the photosynthetic functionality in details, the leaf samples of primed plants were exposed to different stressors, including SO2, PEG, and NaCl. The maximum quantum yield of photosystem II (PS II) was higher in the leaf samples of primed plants, while the non-photochemical quenching (NPQ) of primed plants was decreased when leaf samples were exposed to the stressors. Correlation analysis showed the association of initial PIabs with post-stress FV/FM and NPQ. Stressors attenuated the association of initial PIabs with both FV/FM and NPQ, while priming plants with GABA, melatonin, or GABA + melatonin minimized the effect of stressors by attenuating these correlations. In conclusion, priming plants with both GABA and melatonin improved growth and photosynthetic performance of Vicia faba and mitigated the effects of abiotic stressors on the photosynthetic performance.

The most popular Iranian cantaloupe ‘Samsoori’ is highly susceptible to devastating viruses transmitted by Aphis gossypii. A dominant gene (Vat) causing resistance to the aphid and viruses was detected in ‘Ginsen Makuwa’ in spite of its low fruit quality. They were crossed and the segregating offspring were assessed for combining favorable traits with Vat gene. In the F2 population, moderate to high broad-sense heritability estimates were found for measured traits including, fruit weight (0.78) and soluble solid content (SSC) (0.7). The F3 families were significantly different from each other for earliness, fruit shape indices, cavity, flesh thickness, SSC, and fruit numbers per plant. Resistant and susceptible plants were determined by genotyping 210 plants in F4 generation using a dominant DNA marker for the resistant allele of Vat gene. Out of 15 selected F3 families, four were susceptible, three were homozygote resistant and six showed segregation in their progeny for the Vat gene. Selection assisted by Vat gene marker was a very useful and applied approach for the identification of healthy plants along with phenotypic selection.

In this study, the effect of spraying mother plants with various levels of putrescine, spermidine, and cycocel (each at 0, 50, 500, and 5000 mg/l) were assessed on the frequency of haploid embryos produced from unfertilized ovaries and subsequent regeneration of derived embryos. Significantly higher haploid embryos were obtained when mother plants were sprayed with putrescine at 500 mg/l (5.2 embryos/fruit), spermidine at 50 mg/l (4.8 embryos/fruit), and cycocel at 50 mg/l (5.2 embryos/fruit) as compared to the control (without spraying, 3.2 embryos/fruit). However, embryogenesis induction was decreased drastically as the concentration of all the three compounds tested was increased and the lowest haploid embryos were observed when 5000 mg/l of spermidine (0.4 embryos/fruit) or cycocel (2.0 embryos/fruit) were applied. Only spermidine at 50 mg/l led to 100% regeneration into fully developed plantlets. The seed setting and size of fruits were also affected by polyamines and cycocel applications. Ploidy analysis using a flow cytometer indicated that all regenerated plantlets contain the gametic chromosome number (n = x = 7) of parental plants and the results of chromosome counting also confirmed the haploid nature of regenerated plantlets. It can be concluded that the induction of haploid embryogenesis from unfertilized ovaries after pollination with irradiated pollen and subsequent conversion of derived embryos into the plantlets could be improved in Cucumis sativus L. by applying appropriate levels of putrescine, spermidine, and cycocel.

The purpose of this research was to evaluate the combining ability of six local Iranian and one imported cantaloupe cultivar. Heritability of traits was estimated using a half-diallel mating design. Seven parents and their crosses were evaluated in 2013 and 2014. The greatest general combining ability (GCA) for yield and fruit number was for “Rish-baba” (0.53 kg/plant and 0.3, respectively). The cultivar “Ananasi” had the highest GCA for fruit weight and soluble solids content (SSC) (0.088 kg and 1.4, respectively). “Ananasi” presented the highest GCA values for fruit firmness, chlorophyll a and b and carotenoid content, as well as the highest total chlorophyll content. The cross Garmak × Rish-baba showed the highest specific combining ability (SCA) for yield with heterosis value of 99%. High heritability estimates for SSC (0.52), flesh thickness (0.61) and concentration of chlorophyll a (0.7) were obtained. Although there were significant SCAs for yield, the parents are suggested to be improved prior to hybrid development. The parent “Ananasi” appears to be a suitable donor in breeding programmes.

A new protocol for in vitro regeneration through direct somatic embryogenesis for two muskmelon cultivars (Cucumis melo L., “Mashhadi” and “Eivanaki”) is reported. Somatic embryos were obtained culturing 4- and 8-day-old cotyledons, seeds, and hypocotyls on Murashige and Skoog medium supplemented with three different hormonal combinations never tested so far for melon (naphthoxyacetic acid (NOA) + thidiazuron (TDZ), NOA + 6-banzylaminopurine (BAP), and 2,4-dichlorophenoxyacetic acid (2,4-D) + N-(2-chloro-4-pyridyl)-N′-phenylurea (4-CPPU)). Results were compared with those obtained when explants were cultivated in the presence of 2,4-D + BAP, previously used on melon. Embryogenesis occurred more successfully in 4-day-old cotyledons and seeds than hypocotyls and 8-day-old cotyledons. The best result was achieved with NOA + BAP. Genotypes significantly affected embryogenesis. The number of embryos in “Eivanaki” was significantly higher than that in “Mashhadi.” Embryo proliferation when explants were maintained in jars (9.3%) was found to be higher compared to that in petri dishes. For the first time, genetic stability of regenerated melon plants was evaluated using inter-simple sequence repeat markers. Polymerase chain reaction (PCR) products demonstrated a total of 102 well-resolved bands, and regenerants were 93% similar compared to the mother plant. Somaclonal changes during embryogenesis were evaluated by flow cytometry, showing 91% of the same patterns in regenerated plants. The results suggest that the new hormone components are effective when applied for in vitro embryogenesis of muskmelon as they show a high frequency in regeneration and genetic homogeneity.

The effect of two host plant species including eight genotypes of melon (Cucumis melo L.) and four genotypes of cucumber (Cucumis sativus L.) was studied on reproductive parameters: life expectancy and mortality of Tetranychus urticae (Koch) at 25 ± 1 °C, 60 ± 5% rh and a photoperiod of 16L:8D hours. The results indicated that the highest value of the gross fecundity rate of T. urticae was 96.72 ± 16.70 (eggs/female) on Mir sultan and the lowest value was 14.33 ± 0.88 on Ananasi. The maximum value of gross fertility rate (41.55 ± 4.79) was recorded on Sultan, while the minimum value (1.38 ± 0.08) was recorded on Ananasi. The net fecundity rate was varied from 0.47 ± 0.09 on Ananasi to 23.53 ± 3.96 eggs/female on Sultan. The net fertility rate was 12.96 ± 2.18 on Sultan and 0.04 ± 0.009 on Ananasi, which was the maximum and minimum values, respectively. The range of gross hatch rate on different melon and cucumber genotypes was 9.67% on Ananasi to 72.46% on Super sultan. The cohort reared on Super sultan h...

SummaryThe existence of antixenotic resistance to the two-spotted spider mite [Tetranychus urticae Koch (Acari: Tetranychidae)] was investigated in 36 melon (Cucumis melo L.) genotypes using choice tests. The results revealed significant genetic diversity for this trait, and resistant (‘Dastanbu 1’, ‘’Darunghermez’, ‘Zard-Jalali’, and ‘Kharboze’) and susceptible (‘Garmsari’, ‘Zard-khareji’, ‘Bargney’, and ‘Sabz’) genotypes were identified. These four resistant and four susceptible genotypes were used in follow-up experiments in order to assess their mechanisms of antibiosis and related enzyme activities. Antibiosis data against T. urticae were collected by assessing the fecundity of mated female mites on melon leaf discs in the laboratory. The number of eggs laid by each female per day showed significant differences between genotypes. The lowest numbers of eggs were laid on ‘Darunghermez’ and ‘Dastanbu 1’, while the highest numbers of eggs were laid on ‘Garmsari’ and ‘Zard-khareji’. The activities of both...

Cucumber is an important fruity vegetable worldwide. It is consumed in some eastern countries like Iran not only for salad and pickled but also as a table fruit. Therefore, organoleptic characteristics including taste, aroma, firmness and other traits affecting on consumer savor should be more considered in cucumber breeding. In this study 16 selected Iranian local cultivars were planted and their fruits evaluated for aroma, taste and external attribute by panel test. In addition, proposed effective parameters including dry matter of fruits, potassium content, ash percent and texture firmness were measured. A significant difference was observed among the most traits. The results showed that the highest flavor related to genotypes with high taste, aroma, potassium content and dry matter and lowest skin firmness. G 85 and G 17 had the best taste and aroma. On the basis of cluster analysis, cultivars were divided into four groups. Aroma had a positive correlation with taste and dry matter. Increasing of dry matter content induced increasing of fruit aroma and taste.

The extra light intensity or light stress in summer is a restrict factor in many area of the world. The effects of different levels of solar radiation interception were studied on growth and yield of cucumber hybrid Super Dominus in field. One month cucumber seedlings were transplanted under curtains making different levels of shading 15, 35 and 60% of solar radiation and full sunlight, as control. The experimental design was completely randomized with four replicates and each experimental unit includes 10 plants. The results showed that increasing shading density up to 35% led to an increase in the number of fruits per plant. However, the number of fruits tended to decrease as shading density increased to 60%. Shading density greatly influenced the physiological disorders like sun-scald of cucumber fruits. The result also suggested that plants submitted to 35% shading showed the highest yield.

Efficient somatic embryogenesis simplifies proliferation and gene transformation of many plants. A system for induction of direct somatic embryogenesis via suspension cultures in an Iranian melon cultivar (Khatooni) was optimized. Somatic embryos were induced from quiescent seed cotyledons on liquid MS basal medium supplemented with some osmotic materials. Effect of PEG 6000, PEG 4000, glucose and sucrose were evaluated on induction of somatic embryos. The excised cotyledons were cultured in liquid media and cultures were placed on a gyratory shaker (115 rpm) for two weeks and then crossed through 50 μM metal mesh. The caught embryos were eventually moved on a solid MS medium for further growth and maturation. The number of induced embryos was significantly different in various osmotic materials. The best result was obtained from medium supplemented with 60 g/L PEG 6000. A large number of cotyledonary somatic embryos (approximately 100 embryos from each explant) were produced in this treatment while the number of embryos in glucose and sucrose treatments was less than 30 for each explant. Using the PEG, suggested a quick and efficient way for direct induction of somatic embryogenesis in melon.

We report the first successful regeneration of haploid lines in persian walnut (Juglans regia) developed by in situ parthenogenesis followed by embryo rescue. Female flowers of cultivars Hartley and Pedro and two native Iranian selections (Z63 and Z67) were pollinated using pollen of selections Z53 and Z30 that had been irradiated with gamma rays at five doses (50, 150, 300, 600, and 900 Gy). Gamma-irradiated pollen induced fruit set and development of some parthenogenetic embryos. The immature embryos were excised 30 and 45 days after pollination, cultured in vitro, and then stratified for 30 days at 4 °C to overcome dormancy. Ploidy level of the resulting plantlets was determined by chromosome counting and flow cytometry. Haploid plants were obtained from ‘Hartley’, ‘Pedro’, Z63, and Z67 after pollination using pollen irradiated at 300 and 600 Gy. Plants obtained from pollen irradiated at 50 and 150 Gy were all diploid. Molecular marker analysis using four simple sequence repeat (SSR) markers also showed that all the diploid plants recovered were zygotic and no spontaneous double haploid plants were obtained in this work. Also, the haploid plantlets presented only one allele of their female parents. These profiles confirmed the parthenogenetic origin of the obtained haploid plants. The techniques used to induce haploid walnut plants by irradiated pollen were successful and could be used in breeding programs and accelerate genome analysis in this plant in which the genome size is approximately three times the size of the human genome.