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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.

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.

Phytophthora melonis is the causal agent of damping-off or crown rot, one of the most destructive cucumber diseases that causes severe economic losses in Iran and some other parts of the world. Despite intense research efforts made in the past years, no permanent cure currently exists for this disease. With the aim to understand the molecular mechanisms of defense against P. melonis, root collars and leaves of four cucumber genotypes consisting of resistant Ramezz; moderately resistant Baby and very susceptible Mini 6-23 and Extrem, were monitored for quantitative gene expression analysis of five antifungal and/or anti-oomycete genes (CsWRKY20, CsLecRK6.1, PR3, PR1-1a and LOX1) at three points after inoculation with P. melonis. The gene expression analysis indicated that P. melonis strongly enhanced the expression of these genes after inoculation in both leaves and root collars. Further, not only the transcript levels of these genes were significantly higher in the resistant and moderately resistance genotypes, but also the time point of the highest relative expression ratio for the five genes was different in the four cucumber genotypes. CsWRKY20 and PR3 showed the maximum expression in Ramezz at 48 hours post inoculation (hpi) while CsLecRK6.1, and LOX1 showed the highest expression at 72 hpi. In addition, PR1-1a showed the maximum expression in the Baby at 72 hpi. Root collars responded faster than leaves and some responses were more strongly up-regulated in root collars than in leaves. The genes found to be involved in disease resistance in two different organs of cucumber after pathogen infection. The results suggest that increased expression of these genes led to activation of defense pathways and could be responsible for a reduced P. melonis colonization capacity in Ramezz and Baby. Overall, this work represents a valuable resource for future functional genomics studies to unravel the molecular mechanisms of C. sativus- P. melonis interaction.

Application of chemical mutagens as important factors is very practical for successful haploidization techniques in Cucurbitaceae through pollen grain deactivation and then immature embryo rescue. The present research investigated the effects of genotype, male flower age, receptor plant, and chemical mutagenesis (NaN 3 and colchicine) on pollen grain deactivation as well as seed production (number of total, full, half-full, and empty seeds) and morphological traits. Moreover, the effects of different plant growth regulators were tested on embryo cultures. The effects of different factors (mutagen, genotype, flower age) were investigated on plant regeneration from immature embryos that were inspected from half-full and empty seeds. Based on this study, some mutagenic treatments (0.005 colchicine and 0.0012 NaN 3 ) led to the highest values of morphological and fruit yield traits in control plants, while 0.005 and 0.025 NaN 3 led to reduced values of these traits. Among the genotypes, NBDC3 showed the highest number of different types of seeds. Among different chemical mutagens, NaN 3 (0.0012 mg/L) and colchicine (0.005 mg/L) produced the greatest effects on seed production traits. Moreover, the highest values for all seed-related traits were recorded for crossing with fresh male flowers, whereas crossing with old male flowers contributed to the decline of seed-related traits. Mutagen-treated plants showed the highest empty seed numbers. Furthermore, the highest total and half-full seed numbers were obtained using 0.0012 and 0.005 mg/L NaN 3 and colchicine. Results revealed that the highest and lowest regeneration percentages (66.67% and 26.67%) belonged to the media containing BAP+Kin+IBA (2+1+0.5) mg/L and BAP+Kin+IBA+NAA (2+1+0.5+0.1) mg/L, respectively. These media were used for immature embryo culture. Finally, genotypes NBDC1 and NBDC3 treated with 0.005 colchicine and 0.012 NaN 3 showed higher frequencies of plant regeneration from immature embryos extracted from half-full and empty seeds.

Grain yield and yield components are the main important traits involved in durum wheat (Triticum turgidum L.) improvement programs. The purpose of this research was to identify quantitative trait loci (QTL) associated with yield components such as 1000 grain weight (TGW), grain weight per spike (GWS), number of grains per spike (GNS), spike number per m2 (SN), spike weight (SW), spike harvest index (SHI) and harvest index (HI) using microsatellite markers. Populations of F3 and F4 lines derived from 151 F2 individuals developed from a cross between Oste-Gata, a drought tolerant, and Massara-1, a drought susceptible durum wheat genotypes, were used. The populations were evaluated under four environmental conditions including two irrigation regimes of drought stress at terminal growth stages and normal field conditions in two growing seasons. Two hundred microsatellite markers reported for A and B genomes of bread wheat were used for parental polymorphism analysis and 30 polymorphic markers were applied to genotype 151 F2:3 families. QTL analysis was performed using genome-wide single marker regression analysis (SMA) and composite interval mapping (CIM). The results of SMA revealed that about 20% of the phenotypic variation of harvest index and TGW could be explained by Xcfd22-7B and Xcfa2114-6A markers in different environmental conditions. Similarly, Xgwm181-3B, Xwmc405-7B and Xgwm148-3B and marker Xwmc166-7B were found to be associated with SHI and GWS, respectively. A total of 20 minor and major QTL were detected; five for TGW, two for GWS, two for GNS, three for SN, five for HI, two for SHI and one for SW. The mapped QTL associated with ten markers. Moreover, some of these QTL were prominent and stable under drought stress and non drought stress environments and explained up to 49.5% of the phenotypic variation.

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.

Induction of embryonic callus through available asexual explant culture is applied in the protection and maintenance of cytoplasmic-male sterility and in the maintenance of other lines of onion Allium cepa L. . Usage of the Plackett?Burman PB experimental design has been suggested as a screening method for many variables that influence the desired induction. In order to overcome limitations of standard experimental designs and prioritization of media culture components, a systematic investigation was carried out using the PB design. In this investigation, the effects of different factors such as 2,4-D, putrescine, carbohydrate sources maltose, sorbitol, and sucrose , silver nitrate, glutamine, and glycine concentrations were assayed on callus and embryo induction through mature zygotic embryo explant culture. Out of the eight medium components screened, the four components of putrescine, glutamine, 2,4-D, and glycine were found to contribute positively to the callus production with a maximum production rate of 97.14%. The normal plot and linear regression equation with positive largest coefficient showed that putrescine had the highest significant positive effect with 200 mg/L and three elements comprising 2,4-D and glycine showing a significant reducing effect on callus induction. In embryonic callus induction, a wide range of responses were observed from 0% to 100% in the 21 trials. Results of linear regression data showed that among the eight elements, 2,4-D, glutamine, and glycine had significant effects on embryo production. Glycine and 2,4-D had the highest 26.34% and the lowest 8.33% contribution to explaining embryonic callus induction, respectively. A wide range of responses 0 to 44.1 mg were observed in the Plackett-Burman design with respect to the fresh weight. The regression analysis for the Plackett-Burman design PBD demonstrated that glycine, sorbitol, and sucrose were of high influence on the fresh weight P ≤ 0.05 . Glycine 31.4% and sucrose 6.7% were found to have the highest and lowest contribution to the fresh weight of callus, respectively. Thus, this practical article seeks to show some helpful statistical approaches to typical problems in data analyses of tissue culture research.