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Objective The importance of wild relatives in wheat breeding has caused a lot of investigations to study the genetic diversity and population structures in different species of wild wheat, using various molecular markers. The purpose of this study was to investigate the molecular diversity of 90 different accessions of Aegilops tauschiiand analyzing the genetic structure for clustering the populations using CAAT box-derived polymorphism (CBDP) markers. Materials and methods In the present study, the genetic diversity and population structure of 90 different accessions of Ae. tauschii collected from different geographical areas of Iran, was evaluated using 12 CBDP primers. Results Based on the results, the 12 primers amplified 141 bands in which 91 were polymorphic with an average of 7.58 bands pre primer. The polymorphism information content (PIC) and marker index (MI) for the CBDP primers ranged from 0.40 to 0.49 and 1.49 to 4.99, respectively. Primers CB9, CB12 and CB1 showed a high efficiency in genetic discrimination of evaluated accessions. Population structure analysis classified evaluated accessions into three main groups with 10, 18 and 30 accessions respectively and other accessions recognized as a mixture accessions. In this study, subpopulation NO.1 had the highest values of genetic diversity indices such as number of effective alleles (Ne), Shannon index (I) and heterozygosity (He). Among Ae. tauschii populations a very low genetic differentiation (Gst: 0.03) and high gene flow (Nm: 18.58) were observed. The dendrogram resulted from cluster analysis categorized the assessed accessions into three clusters which accordance with genetic structural analysis results. Conclusions Overall, the results of different parameters showed that the CBDP, is an appropriate marker system for assessing the genetic diversity of Aegilops tauschii accessions. Regarding to the results of genetic structural analysis and diversity parameters, a conservation program is recommended for management of Aegilops germplasm as a valuable genetic resource in the wheat breeding programs.

Cucumber (Cucumis sativus L.) damping-off disease caused by Phytophthora melonis is a limiting factor affecting cucurbit production. This study assessed a collection of 38 domestic and exotic commercial cucumber genotypes for damping-off resistance at transplanting and 50% flowering. Plants were classified using a four-score scale, the average damping-off percentage ranging from 7.92% (resistant) to 88.01% [highly susceptible (HS)]. Most of the genotypes were susceptible and HS to P. melonis. These genotypes were analyzed with 15 inter-simple sequence repeat (ISSR) markers. A total of 317 bands were produced, of which 297 bands (93.69%) were polymorphic. The primer ISSR29 possessed the highest resolving power, polymorphic information content and marker index value, which could be the most informative primer for distinguishing cucumber genotypes. Cluster analysis and principal component analysis were carried out and there was a probable connection between cucumber genotypes and resistance level against P. melonis, indicating possible application for ISSR in studying disease resistance of cucumber and producing cultivars that resist damping-off. The expression of three candidate genes probably involved in the defence against P. melonis was quantified by quantitative real-time polymerase chain reaction in five cucumber genotypes showing different susceptibility to the pathogen. CsWRKY20, CsLecRK6.1 and LOX1 genes were differentially expressed depending on genotype in early stages of infection. LOX1 was the most expressed gene across experiments and the one that best discriminated between susceptible and resistant genotypes. These results are a valuable resource for future functional genomics studies to unravel the molecular mechanisms of C. sativus/P. melonis interaction.

In this study, gene action, genetic variances (δ2A and δ2D ), and combining abilities were estimated for fruit related traits using North Carolina Design ІІ (NCD ІІ) for ten different parental genotypes of greenhouse cucumber. This experiment was performed over a two-year period from 2014 to 2015. The variance components of male, female, and male × female were found to be significant for all the studied traits in a combined analysis of variance. Genetic component analysis showed that fruit diameter, fruit length, total fruit weight, fruit number in early picking and fruit number per node were predominantly under the additive gene action, but internode length and plant height were under the dominance of gene action. Male × female × environment interaction was significant for total fruit weight. The highest general combining ability (GCA) effect for total fruit yield was observed in Zohal (male parent) and YaldaR2 (female parent) genotypes. GCA estimation revealed that male parent of Adrian 4510 provided good general combiners for total fruit number. Specific combining ability (SCA) estimation determined the suitability of Janeete × Adrian 4510. Salar hybrid exhibited higher positive SCA effects for total fruit yield and total fruit number in early picking.

Haploid and doubled haploid lines can be obtained in a short time using in vitro methods. In this study, unfertilized ovaries of cucumber were harvested and placed on semi-solid MS media as explants in Petri dishes. The thermal shock pretreatment, cucumber genotypes, hormonal combinations and AgNO3 were evaluated as experimental factors in three consecutive experiments. The results of first experiment revealed that the thermal shock pretreatment had a significant influence on embryo induction, and the highest rate of embryogenesis was produced in presence of thermal shock pretreatment and the NAA+2,4-D+KIN+BAP (0.5+0.7+1+1.8) mg/L hormonal combination. The highest rate of callus induction was recorded in combination of absence thermal shock and the NAA+2,4-D+KIN+BAP (1.5+0.7+1+1.8) mg/L hormonal combination. According to the second experiment results, genotypes and the other hormonal combinations in media culture had highly significant effects on embryo and callus induction. The NBDC6*6/32441 genotype had the highest effects on these traits. A combination of BAP (4 mg/L) and 2,4-D (1.5 mg/L) was found to be optimal for embryogenesis. In third experiment, the highest level of embryogenesis (24.93%) and callus (24.19%) induction were found in the local Iranian cultivar in comparison to NBDC6*6/32441 genotype. Silver nitrate treatment had significant effects on the embryo and callus induction. The highest rate of embryo induction was recorded in presence of silver nitrate; however the absence of AgNO3 had a positive effect on the callus induction. In conclusion, the thermal shock pretreatment, silver nitrate, genotype and hormonal combination factors could play key roles in embryo and callus production, independently and simultaneously.

The main objective underlying sunflower breeding programs is to develop high-yielding productive F1 hybrid cultivars. This study was conducted to investigate the genetic control of some agro-morphological traits of new sunflower F1 hybrids. For this purpose, fourteen inbred lines of sunflower were crossed with three male sterile inbred lines. Their hybrids (14 hybrids) were then evaluated against three control cultivars. The data thus obtained were analyzed using the nested model (North Carolina Design І) as a completely randomized block design (CRBD) with four replications. Analysis of variance showed that the hybrids were significantly different in all the traits studied, except for head and stem diameters. From among the hybrids evaluated, Cms19 × Rn1-81 was found to have the highest seed yield and oil content. Cluster analysis classified the hybrids into four different groups. Genetic analysis showed that days to maturity, seed weight, and oil content (%) were under the additive gene action. Breeding strategies based on selection could be suggested for the improvement of these traits. Head angle, head diameter, seed yield, and oil yield were under the dominance gene action; breeding based on hybridization methods is, therefore, proposed for these traits. Finally, both additive and dominance gene actions were observed to play important roles in the genetic control of plant height and stem diameter.

Abstract: Seed production depends on many factors. In this study, two independent experiments were carried out to investigate the effects of pollination time, crossed node spacing, male flower age, number of crossings on each plant and deletion/non-deletion of other fruits in the crossed nodes on the cross-ability and seed production in greenhouse cucumber. In every experiment, three mentioned factors were assayed based on factorial experiment as a randomized complete block design. Crosses were done on 10 plants in every replication of treatments. The results showed that pollination at 8:00‒9:45 AM, led to higher amount of full seed weight in contrast to other times of pollination. Increasing crossed node spacing from 2‒3 to 4‒5 nodes led to an increase in the number of empty seeds, which was ascribed to the reduced seed production. The highest amount of number of seeds per fruit, seed weigh and number of full seeds were obtained when young male flowers were used. Moreover, higher seed production was obtained from five, instead three crossings on each plant, and the non-deletion of fruits on the crossed nodes. Overall, higher percentage of seed production per fruit was obtained when crossing was done with young male flower in early morning and high number of crossing in every plant.