Ali Tajabadipour; Mohammadreza Fattahi; Zabihollah Zamani; Fatemeh Nasibi; Hossein Hokmabadi
Abstract
Introduction: Spring cold injury is one of the main limiting factors to production and distribution of pistachio. Pistachio is one of the most valuable and exported agricultural crops of Iran. Since, spring frosts results to considerabe damage to this plant, hence, it is important to investigate methods ...
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Introduction: Spring cold injury is one of the main limiting factors to production and distribution of pistachio. Pistachio is one of the most valuable and exported agricultural crops of Iran. Since, spring frosts results to considerabe damage to this plant, hence, it is important to investigate methods for reducing freezing damage. For this reason, selection of rootstocks and cultivars are an important objective in breeding programs. Freezing temperatures (below 0ºC) cause the movement of water from the protoplast to the extracellular space, resulting in the growth of extracellular ice crystals and ultimately, cell dehydration. Plants have developed complex processes to survive and recover from unfavorable conditions. To tolerate cold stresses, plants develop multiple mechanisms, including the accumulation of cryoprotective molecules and proteins, alterations in membrane lipid composition, and primary and secondary metabolite composition, as well as changes in global gene and protein expression Frost affects cell membranes, which become less permeable, and even break, giving rise to the leakage of solute from damaged cells. There is often a good correlation between ion leakage and freezing tolerance (22). Sugars may depress the freezing point of the tissue and act as a nutrient and energy reserve, alter phase properties of membranes in the dry state and act as cryoprotectants to preserve protein structure and function. Other compounds acting similarly are lipids, soluble proteins and free proline (44). Proline seems to have diverse roles under osmotic stress conditions, such as stabilization of proteins, membranes and subcellular structures and protecting cellular functions by scavenging reactive oxygen species (23). The aim of the present study was to evaluate different degrees of sensitivity to low temperatures in different genotypes and ‘Ahmad-Aghaii’ cultivar in relation to physiological and biochemical changes in field conditions.
Materials and Methods: In order to determine the effects of rootstock on pistachio cultivar ‘Ahmad-Aghaii’ under freezing stress conditions, an experiment was carried out as factorial based on a randomized completely design (RCD) with four replications. Treatments consisted of two levels: 1- rootstock genotype (four cold sensitive and tolerant rootstocks) and 2- temperatures (-2 and -4 ºC). The sampling was performed in full bloom stage from apical branches of pistachio cultivar ‘Ahmad-Aghaii’ budded on these rootstock genotypes. The branches in pots contain distillted water treated under -2 and -4 °C for 2 h. After treatment, the chilling index was determined. Flower clusters were used for measuring physiological and biochemical parameters. All determinations were carried out in four triplicates and data were subjected to analysis of variance. Analysis of variance was performed using the ANOVA procedure. Statistical analyses were performed according to the SAS software. Significant differences between means were determined by Duncan’s multiple range tests. P values less than 0.05 were considered statistically significant.
Results and Discussion: The results showed that chilling index was significantly lower in the cold-tolerant rootstocks than cold-sensitive rootstocks at -2 and -4 ºC. Also, Results indicated that electrolyte leakage, hydrogen peroxide (H2O2) and malondialdehyde (MDA) were significantly lower in tolerant rootstocks than sensitive ones. The content of soluble carbohydrate, total protein and proline were significantly higher intolerant rootstocks than sensitive ones. The activity of anti-oxidant enzymes ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) in tolerant rootstocks was greater than sensitive rootstocks. The reaction of temperature and rootstock indicated that electronic leakage, proline, H2O2,و and MDA significantly increased in -4 ºC. The activity of anti-oxidant enzymes APX, GPX and CAT decreased in -4 ºC as compared to -2 °C especially in cold-sensitive rootstocks. Some researchers believe that the accumulation of proline is as an index to select the drought-resistance varieties (26, 48). Stated that there was no comprehensive information about the relationship between the accumulation of proline and tension resistance. Research on apricot and peach confirmed the results of the present study because this pattern is also seen in their proline level (26 and 41). While the starch concentration decreases during the dormancy, the amount of proline increases which is in accordance with their results (36).
Conclusions: In this study, the damage of the membrane increased with decreasing temperature. The results showed that the rootstocks could increase the resistance to cold by increasing the amount of soluble sugars, protein, proline and the activity of the antioxidant system in the shoots and leaves of the scion. Regarding physiological and biochemical studies, it was determined that ‘Ahmad-Aghaii’ cultivar budded on cold tolerant rootstocks had higher soluble sugars, total protein, proline and CAT, APX and GPX enzymes activity and had less chilling index, ion leakage, H2O2 and MDA, which indicates less damage to the membrane of the cell and its contents compared with the cultivar 'Ahmad-Aghaii' budding to sensitive rootstocks. Consequently, the findings of this study selected TR1 as the most tolerant rootstock compared to other ones.
Saeid Mirzaei; Mehdi Rahimi; Ali Tajabadipour; Masoud Bahar; Bahram SharifNabi
Abstract
Introduction: The pistachio (Pistacia vera), a member of the cashew family, is a small tree originating from Central Asia and the Middle East. The tree produces seeds that are widely consumed as food. Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio. ...
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Introduction: The pistachio (Pistacia vera), a member of the cashew family, is a small tree originating from Central Asia and the Middle East. The tree produces seeds that are widely consumed as food. Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio. These other species can be distinguished by their geographic distributions and their seeds which are much smaller and have a soft shell. Continual advances in crop improvement through plant breeding are driven by the available genetic diversity. Therefore, the recognition and measurement of such diversity is crucial to breeding programs. In the past 20 years, the major effort in plant breeding has changed from quantitative to molecular genetics with emphasis on quantitative trait loci (QTL) identification and marker assisted selection (MAS). The germplasm-regression-combined association studies not only allow mapping of genes/QTLs with higher level of confidence, but also allow detection of genes/QTLs, which will otherwise escape detection in linkage-based QTL studies based on the planned populations. The development of the marker-based technology offers a fast, reliable, and easy way to perform multiple regression analysis and comprise an alternative approach to breeding in diverse species of plants. The availability of many makers and morphological traits can help to regression analysis between these markers and morphological traits.
Materials and Methods: In this study, 20 genotypes of Pistachio were studied and yield related traits were measured. Young well-expanded leaves were collected for DNA extraction and total genomic DNA was extracted. Genotyping was performed using 15 RAPD primers and PCR amplification products were visualized by gel electrophoresis. The reproducible RAPD fragments were scored on the basis of present (1) or absent (0) bands and a binary matrix constructed using each molecular marker. Association analysis between molecular date (as independent variable) and morphological data (as dependent variable) was performed using multiple regression analysis to identify informative markers associated with the yield related traits. Multiple regression analysis was conducted using stepwise method of linear regression analysis option of SPSS. Student t-test was performed to assess significance difference between mean trait estimates of genotypes where specific markers were present and absent. Markers shown significant regression values were considered to be associated with the trait under consideration.
Results and Discussion: Finally 11 primers were polymorphic and a total of 56 pieces (loci) were amplified that among these, 36 segments (64.29%) showed polymorphism with an average of 5.09% per primers and the rate of this polymorphism ranged from at least 25% for AJ05 primer up to 87.5% for OPAD02 primer. Polymorphic information content ranged from 0.095 (AJ05 and OPAD14) to 0.39 (OPC05), with an average of 0.23. Stepwise regression analysis between molecular data and traits was performed to identify informative markers associated with yield component traits. Nineteen RAPD fragments were found associated with six yield related traits. Some of RAPD markers were associated with more than one trait in multiple regression analysis that may be due to pleiotropic effect of the linked quantitative trait locus on different traits. However, to better understand these relationships, preparation of segregating population and linkage mapping is necessary. Also, these results could be useful in marker-assisted breeding programs when no other genetic information is available.
Conclusion: This investigation on molecular markers associated with yield traits in Pistachio has provided clues for identification of the genotypes with higher yield value. In breeding programs selection of quality material is often a time-consuming process, and thus marker-assisted selection could be of great useful in identification of promising genotypes with high value of yield traits. Some of RAPD markers can be used for elite selection of Pistachio, particularly when no other genetic information like linkage maps and quantitative trait loci are available for the species. The applications of the RAPD approach enable us to predict positive correlation between data generated by molecular markers and studied traits. Also, the marker–trait association identification will play an important role in plant MAS/QTL breeding programs, especially in plants where genetic information such as linkage map and QTL is not available.
