Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in... more Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in the world. About 282 Iranian pistachio genotypes (Pistacia spp.), together with 22 foreign cultivars (P. vera), were genotyped using 10 simple sequence repeat (SSR) markers to analyse the genetic diversity and relationships among Pistacia species and cultivars. The results revealed that the genetic diversity within P. atlantica subsp. kurdica was considerably lower than in P. vera or P. khinjuk. Principal coordinate analysis revealed a clear separation between the different Pistacia spices, as well as between the Iranian and foreign cultivars. AMOVA analysis showed that the variation between the species, between different populations, and within populations accounted for 41, 9, and 50% of the total variation, respectively. The results demonstrated that the study of genetic diversity and relationships among Pistacia species and cultivars using SSR markers provides important information for the collection and conservation of pistachio germplasm. In addition, the Iranian cultivars had a broader genetic background than that of the foreign cultivars. Thus, they are very important for genetic conservation and the planning of future breeding programmes. We also determined the different levels of genetic diversity that exist between and within the species and populations and showed that gene flow occurs between the Iranian cultivars and wild-type P. vera populations. The study provides practical information that policy-makers and scientists can apply to the conservation and sustainable use of all the species studied.
Characterization of overall genetic diversity is an important foundation in breeding for superior... more Characterization of overall genetic diversity is an important foundation in breeding for superior genotypes. For sesame (Sesamum indicum L.), an important oil seed crop, little is still known about genetic variability in many possible diversity hotspots, one of them postulated to be in Central Asia. We studied 27 sesame accessions, including 13 Iranian genotypes from 7 different locations and 14 exotic genotypes with wide geographical coverage. Variation among populations was characterized by 24 morphological, phenological and reproductive traits and by random amplified polymorphic DNA (RAPD) markers. Across genotypes, a factor analysis summarized the phenotypic traits best by six main factors, and important correlations were observed among key yield, phenological and morphological traits. A cluster analysis based on phenotypic traits separated the genotypes among four major groups and indicated high degree of phenotypic diversity in both the Iranian and the exotic genotypes. Genetic markers further underscored the high variability (Jaccard's similarity coefficient) of Iranian (0.39-0.92) compared with exotic (0.40-0.81) genotypes, consistent with our hypothesis of a diversity hotspot in Iran. A weak correlation was observed among the classifications based on phenotypic traits and RAPD marker data. The results revealed that RAPD markers can efficiently evaluate genetic variation in the sesame germplasm. These data collectively demonstrate large genetic variability among Iranian sesame genotypes that can be considered as a valuable gene pool for sesame breeding programs. Abbreviations: 1000SM -1000-seed mass; AFLP -amplified fragment length polymorphism; CL -capsule length; DFI -days to flowering initiation; DFT -days to flowering termination; LH -leaf hairiness; DMS -diameter of main stem; FC -flower colour; FP -flowering period; HFC -height to the first capsule; IMC -days to initial maturity of capsules; ISSR -inter simple sequence repeat; MP -maturity period; NMR -nuclear magnetic resonance; NB -number of branches; NCC -number of carpels per capsule; NCPnumber of capsules per plant; NFLA -number of flowers per leaf axil; NSC -number of seeds per capsule; OC -seed oil content; PCA -principal coordinate analysis; P G -growing season precipitation; PH -plant height; RAPD -random amplified polymorphic DNA; RP -reproductive period; SCC -seed coat colour; SMLB -seed mass on lateral branches; SMMS -seed mass on main stem; SYP -seed yield per plant; SRAP -sequence-related amplified polymorphism; SSR -simple sequence repeat; T G,min -growing season minimum temperature; T G,max -growing season maximum temperature; TMC -days to terminal maturity of capsules; UPGMA -unweighted pair group method with arithmetic mean.
Terpenoid synthases constitute a highly diverse gene family producing a wide range of cyclic and ... more Terpenoid synthases constitute a highly diverse gene family producing a wide range of cyclic and acyclic molecules consisting of isoprene (C5) residues. Often a single terpene synthase produces a spectrum of molecules of given chain length, but some terpene synthases can use multiple substrates, producing products of different chain length. Only a few such enzymes has been characterized, but the capacity for multiple-substrate use can be more widespread than previously thought. Here we focused on germacrene A synthase (GAS) that is a key cytosolic enzyme in the sesquiterpene lactone biosynthesis pathway in the important medicinal plant Achillea millefolium (AmGAS). The full length encoding gene was heterologously expressed in Escherichia coli BL21 (DE3), functionally characterized, and its in vivo expression was analyzed. The recombinant protein catalyzed formation of germacrene A with the C15 substrate farnesyl diphosphate (FDP), while acyclic monoterpenes were formed with the C10 substrate geranyl diphosphate (GDP) and cyclic monoterpenes with the C10 substrate neryl diphosphate (NDP). Although monoterpene synthesis has been assumed to be confined exclusively to plastids, AmGAS can potentially synthesize monoterpenes in cytosol when GDP or NDP become available. AmGAS enzyme had high homology with GAS sequences from other Asteraceae species, suggesting that multi-substrate use can be more widespread among germacrene A synthases than previously thought. Expression studies indicated that AmGAS was expressed in both autotrophic and heterotrophic plant compartments with the highest expression levels in leaves and flowers. To our knowledge, this is the first report on the cloning and characterization of germacrene A synthase coding gene in A. millefolium, and multi-substrate use of GAS enzymes. Citation: Pazouki L, Memari HR, Kännaste A, Bichele R and Niinemets Ü (2015) Germacrene A synthase in yarrow (Achillea millefolium) is an enzyme with mixed substrate specificity: gene cloning, functional characterization and expression analysis. Front. Plant Sci. 6:111.
All tree species possess genes encoding terminal enzymes responsible for volatile isoprenoid synt... more All tree species possess genes encoding terminal enzymes responsible for volatile isoprenoid synthesis. However, only in some species, these genes are expressed constitutively in leaves, while terpenoid emissions can be triggered by abiotic and biotic stress factor in essentially all species. This chapter analyses the biochemical diversity of volatile isoprenoid synthases and investigates the genomic modifications responsible for constitutive volatile production in trees. Plant terpenoids are up to three-domain proteins with either one active center in monofunctional synthases, or two active centers in bifunctional synthases. There is evidence of monophyletic origin of modern plant terpenoid synthases from a three-domain synthase in an ancient progenitor followed by extensive gene duplication and domain loss. The terpenoid synthase sequence similarity can be low among distant plant groups, but terpenoid tertiary structure is remarkably similar in different synthases, and this structural similarity is even conserved across domains of life. However, only minor changes in active center structure can lead to major changes in product profiles, indicating that presence of rich terpenoid genetic diversity constitutes an important means for rapid evolutionary adaptations to novel biotic interactions, and to new abiotic stresses in plant habitats.
Understanding within-species variability in terpenoid content and composition is highly relevant ... more Understanding within-species variability in terpenoid content and composition is highly relevant for predicting species adaptive potential to biotic stresses, but there is still limited information on terpene variations even for widespread species. We studied the foliage content and composition of terpenoids, foliage structure, and carbon (C) and nitrogen (N) contents in Pinus sylvestris L. in four Estonian sites ranging from dry forest to raised bog. In the bogs, samples were taken along the environmental gradient from drier margins towards wetter central parts. A chiral column was used to gain insight into the variation in terpene composition. We hypothesized that terpene contents increase and the composition becomes more diverse in more strongly N-limited sites (greater C/N ratio) and that terpene signatures cluster together in sub-sites with similar conditions (drier/wetter). Altogether 37 terpenes were quantified across the sites. Extremely large variability of terpene contents, 48-62% for monoterpenes and 61-89% for sesquiterpenes, was observed. According to the amounts of α-pinenes and (+)-3-carene, we distinguished two different 'pine chemotypes'. Contrary to the hypothesis, terpene contents and variability were the greatest in the dry site with the lowest C/N ratio. However, individual terpenoids correlated differently with C or N in different sites, indicating site effects on terpene composition. Moreover, correlations between the terpenoids and C or N depended on the pine chemotype. The sub-sites with different water regime were more strongly clustered together within the site than across the sites. The study demonstrates extensive variations in terpene contents and composition among the populations and over short spatial distances within the populations, suggesting a large among-and withinpopulation adaptive capacity of P. sylvestris.
Knowledge of pistachio genetic diversity is necessary for the formulation of appropriate manageme... more Knowledge of pistachio genetic diversity is necessary for the formulation of appropriate management strategies for the conservation of these species. We analysed amplified fragment length polymorphisms in a total of 216 pistachio accessions, which included seven populations from three wild species (Pistacia vera, Pistacia khinjuk and Pistacia atlantica subsp. kurdica) and most of the important cultivars from Iran, together with some foreign cultivars. High levels of genetic diversity were detected within the Iranian cultivars, and they showed a clear separation from foreign cultivars, as revealed by unweighted pair group method with arithmetic averaging and supported by analysis of molecular variance. The lowest amount of polymorphism was observed in P. atlantica subsp. kurdica, which showed the lowest number of total bands as compared to the other species. This revealed strong genetic erosion of P. atlantica subsp. kurdica, which reflected a severe decline in habitat and over-exploitation. Based on these findings, strategies are proposed for the genetic conservation and management of pistachio species and cultivars.
Fusarium head blight (FHB or head scab) has become a major limiting factor for sustainable wheat ... more Fusarium head blight (FHB or head scab) has become a major limiting factor for sustainable wheat (Triticum aestivum L.) production around the world. For quantitative trait loci (QTL) analysis of resistance to FHB, F3 plants and F 3:5 lines, derived from a Frontana (moderately resistant)/Seri82 (susceptible) cross, were spray-inoculated in 2001 and 2002, respectively. Artificial inoculations were carried out under
Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in... more Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in the world. About 282 Iranian pistachio genotypes (Pistacia spp.), together with 22 foreign cultivars (P. vera), were genotyped using 10 simple sequence repeat (SSR) markers to analyse the genetic diversity and relationships among Pistacia species and cultivars. The results revealed that the genetic diversity within P. atlantica subsp. kurdica was considerably lower than in P. vera or P. khinjuk. Principal coordinate analysis revealed a clear separation between the different Pistacia spices, as well as between the Iranian and foreign cultivars. AMOVA analysis showed that the variation between the species, between different populations, and within populations accounted for 41, 9, and 50% of the total variation, respectively. The results demonstrated that the study of genetic diversity and relationships among Pistacia species and cultivars using SSR markers provides important information for the collection and conservation of pistachio germplasm. In addition, the Iranian cultivars had a broader genetic background than that of the foreign cultivars. Thus, they are very important for genetic conservation and the planning of future breeding programmes. We also determined the different levels of genetic diversity that exist between and within the species and populations and showed that gene flow occurs between the Iranian cultivars and wild-type P. vera populations. The study provides practical information that policy-makers and scientists can apply to the conservation and sustainable use of all the species studied.
Characterization of overall genetic diversity is an important foundation in breeding for superior... more Characterization of overall genetic diversity is an important foundation in breeding for superior genotypes. For sesame (Sesamum indicum L.), an important oil seed crop, little is still known about genetic variability in many possible diversity hotspots, one of them postulated to be in Central Asia. We studied 27 sesame accessions, including 13 Iranian genotypes from 7 different locations and 14 exotic genotypes with wide geographical coverage. Variation among populations was characterized by 24 morphological, phenological and reproductive traits and by random amplified polymorphic DNA (RAPD) markers. Across genotypes, a factor analysis summarized the phenotypic traits best by six main factors, and important correlations were observed among key yield, phenological and morphological traits. A cluster analysis based on phenotypic traits separated the genotypes among four major groups and indicated high degree of phenotypic diversity in both the Iranian and the exotic genotypes. Genetic markers further underscored the high variability (Jaccard's similarity coefficient) of Iranian (0.39-0.92) compared with exotic (0.40-0.81) genotypes, consistent with our hypothesis of a diversity hotspot in Iran. A weak correlation was observed among the classifications based on phenotypic traits and RAPD marker data. The results revealed that RAPD markers can efficiently evaluate genetic variation in the sesame germplasm. These data collectively demonstrate large genetic variability among Iranian sesame genotypes that can be considered as a valuable gene pool for sesame breeding programs. Abbreviations: 1000SM -1000-seed mass; AFLP -amplified fragment length polymorphism; CL -capsule length; DFI -days to flowering initiation; DFT -days to flowering termination; LH -leaf hairiness; DMS -diameter of main stem; FC -flower colour; FP -flowering period; HFC -height to the first capsule; IMC -days to initial maturity of capsules; ISSR -inter simple sequence repeat; MP -maturity period; NMR -nuclear magnetic resonance; NB -number of branches; NCC -number of carpels per capsule; NCPnumber of capsules per plant; NFLA -number of flowers per leaf axil; NSC -number of seeds per capsule; OC -seed oil content; PCA -principal coordinate analysis; P G -growing season precipitation; PH -plant height; RAPD -random amplified polymorphic DNA; RP -reproductive period; SCC -seed coat colour; SMLB -seed mass on lateral branches; SMMS -seed mass on main stem; SYP -seed yield per plant; SRAP -sequence-related amplified polymorphism; SSR -simple sequence repeat; T G,min -growing season minimum temperature; T G,max -growing season maximum temperature; TMC -days to terminal maturity of capsules; UPGMA -unweighted pair group method with arithmetic mean.
Plant-generated volatiles constitute a sensitive signal of stress response, but quantitative rela... more Plant-generated volatiles constitute a sensitive signal of stress response, but quantitative relationships between the stress severity and volatile emissions have been demonstrated only for a few stresses. Among important stresses in the field, chilling and frost stress in spring and heat stress mid-season can significantly curb productivity. We studied the effects of cold and heat shock treatments on leaf photosynthesis and the emission of the volatile products of the lipoxygenase pathway (LOX, also called green leaf volatiles) and mono-and sesquiterpene emissions in tomato (Solanum lycopersicum cv. Mato) to gain quantitative insights into temperature stress-elicited volatile emissions. Both cold and heat stress treatments ranged from mild, which only weakly affected foliage photosynthesis, to severe, which almost completely inhibited photosynthesis. Under non-stressed conditions, LOX emissions were close to the detection limit, and terpene emissions were low. Both cold and heat stress led to enhancement of LOX emissions according to a switch-type response with essentially no emissions under mild stress and major emissions under severe stress. The emissions of mono-and sesquiterpenes increased gradually with the severity of stress, but cold stress resulted in higher sesquiterpene emissions at any given monoterpene emission level. We suggest that the quantitative relationships between the stress strength and emissions observed in this study provide an important means to characterize the severity of cold and heat stresses.
Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in... more Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in the world. About 282 Iranian pistachio genotypes (Pistacia spp.), together with 22 foreign cultivars (P. vera), were genotyped using 10 simple sequence repeat (SSR) markers to analyse the genetic diversity and relationships among Pistacia species and cultivars. The results revealed that the genetic diversity within P. atlantica subsp. kurdica was considerably lower than in P. vera or P. khinjuk. Principal coordinate analysis revealed a clear separation between the different Pistacia spices, as well as between the Iranian and foreign cultivars. AMOVA analysis showed that the variation between the species, between different populations, and within populations accounted for 41, 9, and 50% of the total variation, respectively. The results demonstrated that the study of genetic diversity and relationships among Pistacia species and cultivars using SSR markers provides important information for the collection and conservation of pistachio germplasm. In addition, the Iranian cultivars had a broader genetic background than that of the foreign cultivars. Thus, they are very important for genetic conservation and the planning of future breeding programmes. We also determined the different levels of genetic diversity that exist between and within the species and populations and showed that gene flow occurs between the Iranian cultivars and wild-type P. vera populations. The study provides practical information that policy-makers and scientists can apply to the conservation and sustainable use of all the species studied.
Characterization of overall genetic diversity is an important foundation in breeding for superior... more Characterization of overall genetic diversity is an important foundation in breeding for superior genotypes. For sesame (Sesamum indicum L.), an important oil seed crop, little is still known about genetic variability in many possible diversity hotspots, one of them postulated to be in Central Asia. We studied 27 sesame accessions, including 13 Iranian genotypes from 7 different locations and 14 exotic genotypes with wide geographical coverage. Variation among populations was characterized by 24 morphological, phenological and reproductive traits and by random amplified polymorphic DNA (RAPD) markers. Across genotypes, a factor analysis summarized the phenotypic traits best by six main factors, and important correlations were observed among key yield, phenological and morphological traits. A cluster analysis based on phenotypic traits separated the genotypes among four major groups and indicated high degree of phenotypic diversity in both the Iranian and the exotic genotypes. Genetic markers further underscored the high variability (Jaccard's similarity coefficient) of Iranian (0.39-0.92) compared with exotic (0.40-0.81) genotypes, consistent with our hypothesis of a diversity hotspot in Iran. A weak correlation was observed among the classifications based on phenotypic traits and RAPD marker data. The results revealed that RAPD markers can efficiently evaluate genetic variation in the sesame germplasm. These data collectively demonstrate large genetic variability among Iranian sesame genotypes that can be considered as a valuable gene pool for sesame breeding programs. Abbreviations: 1000SM -1000-seed mass; AFLP -amplified fragment length polymorphism; CL -capsule length; DFI -days to flowering initiation; DFT -days to flowering termination; LH -leaf hairiness; DMS -diameter of main stem; FC -flower colour; FP -flowering period; HFC -height to the first capsule; IMC -days to initial maturity of capsules; ISSR -inter simple sequence repeat; MP -maturity period; NMR -nuclear magnetic resonance; NB -number of branches; NCC -number of carpels per capsule; NCPnumber of capsules per plant; NFLA -number of flowers per leaf axil; NSC -number of seeds per capsule; OC -seed oil content; PCA -principal coordinate analysis; P G -growing season precipitation; PH -plant height; RAPD -random amplified polymorphic DNA; RP -reproductive period; SCC -seed coat colour; SMLB -seed mass on lateral branches; SMMS -seed mass on main stem; SYP -seed yield per plant; SRAP -sequence-related amplified polymorphism; SSR -simple sequence repeat; T G,min -growing season minimum temperature; T G,max -growing season maximum temperature; TMC -days to terminal maturity of capsules; UPGMA -unweighted pair group method with arithmetic mean.
Terpenoid synthases constitute a highly diverse gene family producing a wide range of cyclic and ... more Terpenoid synthases constitute a highly diverse gene family producing a wide range of cyclic and acyclic molecules consisting of isoprene (C5) residues. Often a single terpene synthase produces a spectrum of molecules of given chain length, but some terpene synthases can use multiple substrates, producing products of different chain length. Only a few such enzymes has been characterized, but the capacity for multiple-substrate use can be more widespread than previously thought. Here we focused on germacrene A synthase (GAS) that is a key cytosolic enzyme in the sesquiterpene lactone biosynthesis pathway in the important medicinal plant Achillea millefolium (AmGAS). The full length encoding gene was heterologously expressed in Escherichia coli BL21 (DE3), functionally characterized, and its in vivo expression was analyzed. The recombinant protein catalyzed formation of germacrene A with the C15 substrate farnesyl diphosphate (FDP), while acyclic monoterpenes were formed with the C10 substrate geranyl diphosphate (GDP) and cyclic monoterpenes with the C10 substrate neryl diphosphate (NDP). Although monoterpene synthesis has been assumed to be confined exclusively to plastids, AmGAS can potentially synthesize monoterpenes in cytosol when GDP or NDP become available. AmGAS enzyme had high homology with GAS sequences from other Asteraceae species, suggesting that multi-substrate use can be more widespread among germacrene A synthases than previously thought. Expression studies indicated that AmGAS was expressed in both autotrophic and heterotrophic plant compartments with the highest expression levels in leaves and flowers. To our knowledge, this is the first report on the cloning and characterization of germacrene A synthase coding gene in A. millefolium, and multi-substrate use of GAS enzymes. Citation: Pazouki L, Memari HR, Kännaste A, Bichele R and Niinemets Ü (2015) Germacrene A synthase in yarrow (Achillea millefolium) is an enzyme with mixed substrate specificity: gene cloning, functional characterization and expression analysis. Front. Plant Sci. 6:111.
All tree species possess genes encoding terminal enzymes responsible for volatile isoprenoid synt... more All tree species possess genes encoding terminal enzymes responsible for volatile isoprenoid synthesis. However, only in some species, these genes are expressed constitutively in leaves, while terpenoid emissions can be triggered by abiotic and biotic stress factor in essentially all species. This chapter analyses the biochemical diversity of volatile isoprenoid synthases and investigates the genomic modifications responsible for constitutive volatile production in trees. Plant terpenoids are up to three-domain proteins with either one active center in monofunctional synthases, or two active centers in bifunctional synthases. There is evidence of monophyletic origin of modern plant terpenoid synthases from a three-domain synthase in an ancient progenitor followed by extensive gene duplication and domain loss. The terpenoid synthase sequence similarity can be low among distant plant groups, but terpenoid tertiary structure is remarkably similar in different synthases, and this structural similarity is even conserved across domains of life. However, only minor changes in active center structure can lead to major changes in product profiles, indicating that presence of rich terpenoid genetic diversity constitutes an important means for rapid evolutionary adaptations to novel biotic interactions, and to new abiotic stresses in plant habitats.
Understanding within-species variability in terpenoid content and composition is highly relevant ... more Understanding within-species variability in terpenoid content and composition is highly relevant for predicting species adaptive potential to biotic stresses, but there is still limited information on terpene variations even for widespread species. We studied the foliage content and composition of terpenoids, foliage structure, and carbon (C) and nitrogen (N) contents in Pinus sylvestris L. in four Estonian sites ranging from dry forest to raised bog. In the bogs, samples were taken along the environmental gradient from drier margins towards wetter central parts. A chiral column was used to gain insight into the variation in terpene composition. We hypothesized that terpene contents increase and the composition becomes more diverse in more strongly N-limited sites (greater C/N ratio) and that terpene signatures cluster together in sub-sites with similar conditions (drier/wetter). Altogether 37 terpenes were quantified across the sites. Extremely large variability of terpene contents, 48-62% for monoterpenes and 61-89% for sesquiterpenes, was observed. According to the amounts of α-pinenes and (+)-3-carene, we distinguished two different 'pine chemotypes'. Contrary to the hypothesis, terpene contents and variability were the greatest in the dry site with the lowest C/N ratio. However, individual terpenoids correlated differently with C or N in different sites, indicating site effects on terpene composition. Moreover, correlations between the terpenoids and C or N depended on the pine chemotype. The sub-sites with different water regime were more strongly clustered together within the site than across the sites. The study demonstrates extensive variations in terpene contents and composition among the populations and over short spatial distances within the populations, suggesting a large among-and withinpopulation adaptive capacity of P. sylvestris.
Knowledge of pistachio genetic diversity is necessary for the formulation of appropriate manageme... more Knowledge of pistachio genetic diversity is necessary for the formulation of appropriate management strategies for the conservation of these species. We analysed amplified fragment length polymorphisms in a total of 216 pistachio accessions, which included seven populations from three wild species (Pistacia vera, Pistacia khinjuk and Pistacia atlantica subsp. kurdica) and most of the important cultivars from Iran, together with some foreign cultivars. High levels of genetic diversity were detected within the Iranian cultivars, and they showed a clear separation from foreign cultivars, as revealed by unweighted pair group method with arithmetic averaging and supported by analysis of molecular variance. The lowest amount of polymorphism was observed in P. atlantica subsp. kurdica, which showed the lowest number of total bands as compared to the other species. This revealed strong genetic erosion of P. atlantica subsp. kurdica, which reflected a severe decline in habitat and over-exploitation. Based on these findings, strategies are proposed for the genetic conservation and management of pistachio species and cultivars.
Fusarium head blight (FHB or head scab) has become a major limiting factor for sustainable wheat ... more Fusarium head blight (FHB or head scab) has become a major limiting factor for sustainable wheat (Triticum aestivum L.) production around the world. For quantitative trait loci (QTL) analysis of resistance to FHB, F3 plants and F 3:5 lines, derived from a Frontana (moderately resistant)/Seri82 (susceptible) cross, were spray-inoculated in 2001 and 2002, respectively. Artificial inoculations were carried out under
Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in... more Iran is one of the two major centres of Pistacia diversity and the main producer of pistachios in the world. About 282 Iranian pistachio genotypes (Pistacia spp.), together with 22 foreign cultivars (P. vera), were genotyped using 10 simple sequence repeat (SSR) markers to analyse the genetic diversity and relationships among Pistacia species and cultivars. The results revealed that the genetic diversity within P. atlantica subsp. kurdica was considerably lower than in P. vera or P. khinjuk. Principal coordinate analysis revealed a clear separation between the different Pistacia spices, as well as between the Iranian and foreign cultivars. AMOVA analysis showed that the variation between the species, between different populations, and within populations accounted for 41, 9, and 50% of the total variation, respectively. The results demonstrated that the study of genetic diversity and relationships among Pistacia species and cultivars using SSR markers provides important information for the collection and conservation of pistachio germplasm. In addition, the Iranian cultivars had a broader genetic background than that of the foreign cultivars. Thus, they are very important for genetic conservation and the planning of future breeding programmes. We also determined the different levels of genetic diversity that exist between and within the species and populations and showed that gene flow occurs between the Iranian cultivars and wild-type P. vera populations. The study provides practical information that policy-makers and scientists can apply to the conservation and sustainable use of all the species studied.
Characterization of overall genetic diversity is an important foundation in breeding for superior... more Characterization of overall genetic diversity is an important foundation in breeding for superior genotypes. For sesame (Sesamum indicum L.), an important oil seed crop, little is still known about genetic variability in many possible diversity hotspots, one of them postulated to be in Central Asia. We studied 27 sesame accessions, including 13 Iranian genotypes from 7 different locations and 14 exotic genotypes with wide geographical coverage. Variation among populations was characterized by 24 morphological, phenological and reproductive traits and by random amplified polymorphic DNA (RAPD) markers. Across genotypes, a factor analysis summarized the phenotypic traits best by six main factors, and important correlations were observed among key yield, phenological and morphological traits. A cluster analysis based on phenotypic traits separated the genotypes among four major groups and indicated high degree of phenotypic diversity in both the Iranian and the exotic genotypes. Genetic markers further underscored the high variability (Jaccard's similarity coefficient) of Iranian (0.39-0.92) compared with exotic (0.40-0.81) genotypes, consistent with our hypothesis of a diversity hotspot in Iran. A weak correlation was observed among the classifications based on phenotypic traits and RAPD marker data. The results revealed that RAPD markers can efficiently evaluate genetic variation in the sesame germplasm. These data collectively demonstrate large genetic variability among Iranian sesame genotypes that can be considered as a valuable gene pool for sesame breeding programs. Abbreviations: 1000SM -1000-seed mass; AFLP -amplified fragment length polymorphism; CL -capsule length; DFI -days to flowering initiation; DFT -days to flowering termination; LH -leaf hairiness; DMS -diameter of main stem; FC -flower colour; FP -flowering period; HFC -height to the first capsule; IMC -days to initial maturity of capsules; ISSR -inter simple sequence repeat; MP -maturity period; NMR -nuclear magnetic resonance; NB -number of branches; NCC -number of carpels per capsule; NCPnumber of capsules per plant; NFLA -number of flowers per leaf axil; NSC -number of seeds per capsule; OC -seed oil content; PCA -principal coordinate analysis; P G -growing season precipitation; PH -plant height; RAPD -random amplified polymorphic DNA; RP -reproductive period; SCC -seed coat colour; SMLB -seed mass on lateral branches; SMMS -seed mass on main stem; SYP -seed yield per plant; SRAP -sequence-related amplified polymorphism; SSR -simple sequence repeat; T G,min -growing season minimum temperature; T G,max -growing season maximum temperature; TMC -days to terminal maturity of capsules; UPGMA -unweighted pair group method with arithmetic mean.
Plant-generated volatiles constitute a sensitive signal of stress response, but quantitative rela... more Plant-generated volatiles constitute a sensitive signal of stress response, but quantitative relationships between the stress severity and volatile emissions have been demonstrated only for a few stresses. Among important stresses in the field, chilling and frost stress in spring and heat stress mid-season can significantly curb productivity. We studied the effects of cold and heat shock treatments on leaf photosynthesis and the emission of the volatile products of the lipoxygenase pathway (LOX, also called green leaf volatiles) and mono-and sesquiterpene emissions in tomato (Solanum lycopersicum cv. Mato) to gain quantitative insights into temperature stress-elicited volatile emissions. Both cold and heat stress treatments ranged from mild, which only weakly affected foliage photosynthesis, to severe, which almost completely inhibited photosynthesis. Under non-stressed conditions, LOX emissions were close to the detection limit, and terpene emissions were low. Both cold and heat stress led to enhancement of LOX emissions according to a switch-type response with essentially no emissions under mild stress and major emissions under severe stress. The emissions of mono-and sesquiterpenes increased gradually with the severity of stress, but cold stress resulted in higher sesquiterpene emissions at any given monoterpene emission level. We suggest that the quantitative relationships between the stress strength and emissions observed in this study provide an important means to characterize the severity of cold and heat stresses.
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Papers by Leila Pazouki