Raul Herrera - Academia.edu (original) (raw)

Papers by Raul Herrera

Hormones act as master ripening regulators. In non-climacteric fruit ABA plays a key role in ripe... more Hormones act as master ripening regulators. In non-climacteric fruit ABA plays a key role in ripening. Recently we confirmed in Fragaria chiloensis fruit that in response to ABA treatment the fruit induces ripening associated changes such as softening and color development. In consequence with these phenotypic changes, transcriptional variations associated with cell wall disassembly and anthocyanins biosynthesis were reported. As ABA stimulates ripening of F. chiloensis fruit, the molecular network involved in ABA metabolism was analyzed. Therefore, the expression level of genes involved in ABA biosynthesis and ABA perception were quantified during development of the fruit. Four NCED/CCDs and 6 PYR/PYLs family members were identified in F. chiloensis. Bioinformatics analyses confirmed the existence of key domains related to functional properties. Through RT-qPCR analyses the level of transcripts were quantified. FcNCED1 codifies a protein that displays crucial functional domains and...

Scientia Horticulturae, 2010

... Chandler) at three fruit developmental stages: large green (LG), turning (T) and ripe (R). A ... more ... Chandler) at three fruit developmental stages: large green (LG), turning (T) and ripe (R). A rapid decrease in fruit firmness between LG and T stages was observed in both species; nevertheless firmness reduction in F. chiloensis was steeper than in F. ×ananassa. ...

Postharvest Biology and Technology, 2004

The first noticeable event during the ripening of mountain papaya (Vasconcellea pubescens) is the... more The first noticeable event during the ripening of mountain papaya (Vasconcellea pubescens) is the rapid degreening of the skin, followed by climacteric ethylene and flesh softening. When ethylene perception is blocked by 1-methylcyclopropene (1-MCP, 0.3 l l −1 for 16 h at 20 • C), the increase in ethylene evolution is avoided, and softening and color development are partially delayed. This indicates that ethylene perception is an absolute requirement for ethylene production during ripening and that softening and color development are only partially dependent on ethylene. Our data also suggest that the changes in pH, titratable acidity, and soluble solids are not dependent on ethylene. Mountain papaya fruit displayed the typical climacteric rise in ethylene production, reaching maximum values of 1.8-3.2 mol kg −1 h −1 , and so confirmed the climacteric nature of the fruit. The activity of ACC oxidase paralleled changes in ethylene production. Nevertheless, when 1-MCP treated fruit recover ethylene sensitivity, a big increase in ACC oxidase activity is observed followed by a further increase, but at a reduced level, of ethylene; the reduced ACC content suggests that in these fruit the availability of ACC is limiting ethylene biosynthesis. Finally, our results indicate that treatment of mountain papaya with 1-MCP delays the onset of the climacteric phase, and therefore can be used commercially to extend effectively the short shelf life of this fruit.

Postharvest Biology and Technology, 2007

Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a stro... more Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a strong and characteristic aroma during ripening. The dynamics of aroma volatile production during ripening of whole papaya fruit were analysed by headspace-SPME. The main compounds produced by the fruit were esters (aliphatic and branched) and alcohols: the most abundant esters were ethyl acetate, ethyl butanoate, methyl butanoate and butyl acetate, comprising 88% of the volatiles in fully ripe fruit; butanol was the most abundant alcohol. Among the volatiles produced, ethyl butanoate, ethyl acetate, ethyl hexanoate and ethyl 2-methylbutanoate were found to be the most potent odour compounds. During ripening of mountain papaya fruit there was an increase in the total content of both esters and alcohols. In order to clarify the role of ethylene in aroma formation, mature fruit were treated with 0.3 L L −1 of 1-MCP (16 h at 20 • C) or with 2 g L −1 Ethrel, and then allowed to ripen at 20 • C. The treatment of the fruit with 1-MCP inhibited the rise in ethylene production in the fruit, while Ethrel advanced the development of the climacteric phase. Most esters identified in mountain papaya were dependent on ethylene, showing an increase in production during ripening and in response to Ethrel treatment, and a strong reduction in response to 1-MCP treatment. The data presented provide evidence that most esters produced by mountain papaya are derived from fatty acids and amino acid metabolic pathways, both of them being affected by ethylene.

Phytochemistry, 2010

Difference in fruit pigmentation observed between two botanical forms of Fragaria chiloensis ssp.... more Difference in fruit pigmentation observed between two botanical forms of Fragaria chiloensis ssp. chiloensis (form chiloensis and form patagonica) was studied through transcriptional and chemical approaches. The proportion of different anthocyanins was demonstrated to be characteristic of each botanical form, with pelargonidin 3-glucoside being the most abundant in f. patagonica fruit and cyaniding 3-glucoside as the major one in f. chiloensis fruit. Partial gene sequences of the phenylpropanoid and flavonoid biosynthesis pathways were isolated from the native Chilean strawberry fruits, and used to design gene-specific primers in order to perform transcriptional analyses by qRT-PCR. These genes showed spatial, developmental, and genotypic associated patterns. The red fruit of f. patagonica exhibited higher transcript levels of anthocyanin-related genes and higher levels of anthocyanins compared to the barely pigmented fruit of f. chiloensis. The anthocyanin accumulation in F. chiloensis ssp. chiloensis fruits was concomitant with the particular progress of the transcriptional activity of genes involved in the biosynthesis of flavonoid pigments. The differences in anthocyanin contents, both in terms of type and quantity, between the two botanical forms of F. chiloensis ssp. chiloensis were coincident with the differential transcriptional patterns found in the anthocyanin-related genes.

Phytochemistry, 2013

Anthocyanins and proanthocyanidins (PAs), flavonoid-derived metabolites with different physiologi... more Anthocyanins and proanthocyanidins (PAs), flavonoid-derived metabolites with different physiological roles, are produced by plants in a coordinated manner during fruit development by the action of transcription factors (TFs). These regulatory proteins have either an activating or repressing effect over structural genes from the biosynthetic pathway under their control. FaMYB1, a TF belonging to the R2R3-MYB family and isolated from commercial strawberry fruit (Fragaria×ananassa), was reported as a transcriptional repressor and its heterologous over-expression in tobacco flowers suppressed flavonoid-derived compound accumulation. FcMYB1, an ortholog of FaMYB1 isolated from the white Chilean strawberry (Fragaria chiloensis ssp. chiloensis f. chiloensis), showed higher transcript levels in white (F. chiloensis) than in red (F.×ananassa cv. Camarosa) fruits. In order to assess its contribution to the discolored phenotype in F. chiloensis, FcMYB1 was transiently down-regulated in planta using an RNAi-based approach. Quantitative real-time PCR on FcMYB1 down-regulated fruits resulted an up-regulation of anthocyanidin synthase (ANS) and a strong repression of anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR) transcript accumulation. In addition, these fruits showed increased concentrations of anthocyanins and undetectable levels of flavan 3-ols. Altogether, these results indicate a role for FcMYB1 in regulation of the branching-point of the anthocyanin/PA biosynthesis determining the discolored phenotype of the white Chilean strawberry fruit.

Journal of Plant Growth Regulation, 2012

Loss of verticality in conifers affects the normal wood development by inducing changes and chemi... more Loss of verticality in conifers affects the normal wood development by inducing changes and chemical modifications in tree stems called compression wood. It is known that ethylene influences the response during this abnormal wood-forming process. The expression pattern of genes involved in the ethylene biosynthesis pathway during gravitropic response in gymnosperms has been identified in adult trees. Young seedlings of radiata pine were inclined to reveal the expression pattern of these genes by the quantitative real-time PCR (qRT-PCR) technique. The seedlings were exposed to gravitropic stimuli and harvested after 2.5 and 10 h (early responses) of inclination, and after 24 h (late response). Sampling includes transverse cuts at three heights of the whole stem of inclined seedlings. Our data revealed that genes encoding for 1-aminocyclopropane-1-carboxylate oxidase (ACO) and 1-aminocyclopropane-1-carboxylate synthase (ACS) were differentially expressed during the time of leaning, and, interestingly, at the basal portion of radiata pine stems. Additionally, transcriptional analysis in maritime pine showed a conserved profile of gene activation in conifers, and in mature compression wood, ACO gene transcription was strongly upregulated. These results indicate that the concerted activation of genes involved in ethylene biosynthesis could be responding to leaning signals in young radiata and maritime pine seedlings.

Journal of Photochemistry and Photobiology B: Biology, 2010

Genetic analyses of Gnaphalium's DNA showed a high degree of polymorphism in UV-B irradiated plan... more Genetic analyses of Gnaphalium's DNA showed a high degree of polymorphism in UV-B irradiated plants when compared to controls. Among the five tested primers the four ISSR primers selected for this analysis generated a total of 189 fragments. A high proportion of polymorphic bands ranging from 70% to 28% were found using these ISSR markers. Nei and Li similarity indexes [1] were used to evaluate genetic divergence among plants. The dendrograms obtained using these markers efficiently separate plants from different treatments. A linear relationship was observed between UV-B dose and percentage of dissimilarity which may be related to DNA damage caused by the different UV-B treatments.

Journal of Molecular Graphics and Modelling, 2011

The aroma in fruits is an important attribute of quality that influences consumer's acceptance. T... more The aroma in fruits is an important attribute of quality that influences consumer's acceptance. This attribute is a complex character determined by a set of low molecular weight volatile compounds. In mountain papaya fruit (Vasconcellea pubescens) the aroma is determined mainly by esters, which are produced through an esterification reaction catalyzed by the enzyme alcohol acyltransferase (AAT) that utilizes alcohols and acyl-CoAs as substrates. In order to understand the molecular mechanism involved in the production of esters in this fruit, an AAT gene which has been previously cloned and characterized from mountain papaya (VpAAT1) was expressed in yeasts, and the highest enzyme activity of the recombinant protein was obtained when the enzyme was tested for its ability to produce benzyl acetate. On the other hand, to gain insight the mechanism of action at the molecular level, a structural model for VpAAT1 protein was built by comparative modelling methodology, which was validated and refined by molecular dynamics simulation. The VpAAT1 structure consists of two domains connected by a large crossover loop, with a solvent channel in the center of the structure formed between the two domains. Residues H166 and D170, important for catalytic action, displayed their side chains towards the central cavity of the channel allowing their interaction with the substrates. The conformational interaction between the protein and several ligands was explored by molecular docking simulations, and the predictions obtained were tested through kinetic analysis. Kinetic results showed that the lowest K M values were obtained for acetyl-CoA and benzyl alcohol. In addition, the most favorable predicted substrate orientation was observed for benzyl alcohol and acetyl CoA, showing a perfect coincidence between kinetic studies and molecular docking analysis.

Journal of Chemical Information and Modeling, 2013

Aroma in Vasconcellea pubescens fruit is determined by esters, which are the products of catalysi... more Aroma in Vasconcellea pubescens fruit is determined by esters, which are the products of catalysis by alcohol acyltransferase (VpAAT1). VpAAT1 protein structure displayed the conserved HxxxD motif facing the solvent channel in the center of the structure. To gain insight into the role of these catalytic residues, kinetic and site-directed mutagenesis studies were carried out in VpAAT1 protein. Based on dead-end inhibition studies, the kinetic could be described in terms of a ternary complex mechanism with the H166 residue as the catalytic base. Kinetic results showed the lowest Km value for hexanoyl-CoA. Additionally, the most favorable predicted substrate orientation was observed for hexanoyl-CoA, showing a coincidence between kinetic studies and molecular docking analysis. Substitutions H166A, D170A, D170N, and D170E were evaluated in silico. The solvent channel in all mutant structures was lost, showing large differences with the native structure. Molecular docking and molecular dynamics simulations were able to describe unfavored energies for the interaction of the mutant proteins with different alcohols and acyl-CoAs. Additionally, in vitro site-directed mutagenesis of H166 and D170 in VpAAT1 induced a loss of activity, confirming the functional role of both residues for the activity, H166 being directly involved in catalysis.

Journal of Agricultural and Food Chemistry, 2010

Mountain papaya ( Vasconcellea pubescens ) is a climacteric fruit that develops a strong and char... more Mountain papaya ( Vasconcellea pubescens ) is a climacteric fruit that develops a strong and characteristic aroma during ripening. Esters are the main volatile compounds produced by the fruit, and most of them are dependent on ethylene. As esters are synthesized through alcohol acyltransferases (AAT), a full-length cDNA (VpAAT1) was isolated that displayed the characteristic motifs of most plant acyltransferases. The full-length cDNA sequence was cloned and expressed in yeasts, obtaining a functional enzyme with high AAT activity toward the formation of benzyl acetate. The transcript accumulation pattern provided by qPCR analysis showed that the VpAAT1 gene is expressed exclusively in fruit tissues and that a high level of transcripts is accumulated during ripening. The increase in VpAAT1 transcripts in fruit is coincident with the increase in AAT activity; transcript accumulation is induced by ethylene, and it is avoided by 1-methylcyclopropene (1-MCP) treatment. The data indicate that VpAAT1 is involved in aroma formation and that ethylene plays a major role in regulating its expression.

Botany, 2008

Gomortega keule (Molina) Baillon is a rare Chilean species classified as endangered and currently... more Gomortega keule (Molina) Baillon is a rare Chilean species classified as endangered and currently under conservation. Currently, conservation of this species is carried out by private companies and government agencies, but is done so based more on pragmatic criteria than scientifically based strategies. In this context, information concerning the genetic variability of the species among the different populations over its entire distribution range is incomplete, making it difficult to coordinate management and conservation strategies. Here we report a study to evaluate the genetic variability and population structure of G. keule over its entire distribution in Chile. Twenty-five ISSR primers for 223 individuals from 11 geographical populations were tested to evaluate genetic variability. Results showed a high level of genetic diversity for the species. A high level of genetic differentiation among populations was found, while genetic structure of the geographic populations was also s...

BMC Plant Biology, 2010

Background Plants are subjected to continuous stimuli from the environment and have evolved an ab... more Background Plants are subjected to continuous stimuli from the environment and have evolved an ability to respond through various growth and development processes. Phototropism and gravitropism responses enable the plant to reorient with regard to light and gravity. Results We quantified the speed of maritime pine seedlings to reorient with regard to light and gravity over 22 days. Seedlings were inclined at 15, 30 and 45 degrees with vertical plants as controls. A lateral light source illuminated the plants and stem movement over time was recorded. Depending on the initial angle of stem lean, the apical response to the lateral light source differed. In control and 15° inclined plants, the apex turned directly towards the light source after only 2 h. In plants inclined at 30° and 45°, the apex first reoriented in the vertical plane after 2 h, then turned towards the light source after 24 h. Two-dimensional gel electrophoresis coupled with mass spectrometry was then used to describe ...

Biological Research, 2001

The identification and characterization of differential gene expression from tissues subjected to... more The identification and characterization of differential gene expression from tissues subjected to stress has gained much attention in plant research. The recognition of elements involved in the response to a particular stress enhances the possibility of promoting crop improvement through direct genetic modification. However, the performance of some of the 'first generation' of transgenic plants with the incorporation of a single gene has not always been as expected. These results have stimulated the development of new transgenic constructions introducing more than one gene and capable of modifying complex pathways. Several techniques are available to conduct the analysis of gene regulation, with such information providing the basis for novel constructs specifically designed to modify metabolism. This review deals with techniques that allow the identification and characterization of differentially-expressed genes and the use of molecular pathway information to produce transgenic plants.

Biologia Plantarum, 2013

ABSTRACT In conifers, relationship between ethylene and the response to inclination are not well ... more ABSTRACT In conifers, relationship between ethylene and the response to inclination are not well understood. The aim of this work was to study the consequence for the application of 2-chloroethyl phosphonic acid (ethephon), compound able to release ethylene, in one-year-old Pinus radiata D. Don seedlings subjected to inclination. In plants exposed to inclination for 15 d, increase in thickness of cell walls, more rounded shape of xylem cells, and accumulation of lignin were observed. Ethephon application accelerated significantly these changes; they can be observed after 5 d of inclination. The quantitative polymerase chain reaction (qPCR) showed up-regulation of transcripts from genes encoding phenylalanine ammonia lyase and cinnamyl alcohol dehydrogenase after inclination and their possible ethylene signal-dependence. As conclusion, morphological changes on stem xylem cells in young seedlings of radiata pine exposed to inclination are similar to those observed in compression wood and they are influenced by ethephon application.

Biodiversity and Conservation, 2005

Abstract. Gomortega keule (Molina) Baillon is an endangered, rare species, the only representativ... more Abstract. Gomortega keule (Molina) Baillon is an endangered, rare species, the only representative of its genus, and endemic to Central Chile. Populations of this tree are now fragmented and few individuals can be found in any of them. Genetic diversity was studied in 33 individuals ...

Biological Research, 2001

In 1995, when the entire DNA genome sequence of the first self-replicating organism, Haemophilus ... more In 1995, when the entire DNA genome sequence of the first self-replicating organism, Haemophilus influenzae, was described, the age of genomics was initiated. In the coming months and years the DNA sequences for different plant species will be delivered. In fact, within the last year ...

Journal of Photochemistry and …, 2010

Note to users: The section "Articles in Press" contains peer reviewed accepted articles... more Note to users: The section "Articles in Press" contains peer reviewed accepted articles to be published in this journal. When the final article is assigned to an issue of the journal, the "Article in Press" version will be removed from this section and will appear in the associated ...

Loss of verticality in conifers affects the normal wood development by inducing changes and chemi... more Loss of verticality in conifers affects the normal wood development by inducing changes and chemical modifications in tree stems called compression wood. It is known that ethylene influences the response during this abnormal wood-forming process. The expression pattern of genes involved in the ethylene biosynthesis pathway during gravitropic response in gymnosperms has been identified in adult trees. Young seedlings of radiata pine were inclined to reveal the expression pattern of these genes by the quantitative real-time PCR (qRT-PCR) technique. The seedlings were exposed to gravitropic stimuli and harvested after 2.5 and 10 h (early responses) of inclination, and after 24 h (late response). Sampling includes transverse cuts at three heights of the whole stem of inclined seedlings. Our data revealed that genes encoding for 1-aminocyclopropane-1-carboxylate oxidase (ACO) and 1-aminocyclopropane-1-carboxylate synthase (ACS) were differentially expressed during the time of leaning, and, interestingly, at the basal portion of radiata pine stems. Additionally, transcriptional analysis in maritime pine showed a conserved profile of gene activation in conifers, and in mature compression wood, ACO gene transcription was strongly upregulated. These results indicate that the concerted activation of genes involved in ethylene biosynthesis could be responding to leaning signals in young radiata and maritime pine seedlings.

Postharvest Biology and …, 2007

Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a stro... more Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a strong and characteristic aroma during ripening. The dynamics of aroma volatile production during ripening of whole papaya fruit were analysed by headspace-SPME. The main ...

Hormones act as master ripening regulators. In non-climacteric fruit ABA plays a key role in ripe... more Hormones act as master ripening regulators. In non-climacteric fruit ABA plays a key role in ripening. Recently we confirmed in Fragaria chiloensis fruit that in response to ABA treatment the fruit induces ripening associated changes such as softening and color development. In consequence with these phenotypic changes, transcriptional variations associated with cell wall disassembly and anthocyanins biosynthesis were reported. As ABA stimulates ripening of F. chiloensis fruit, the molecular network involved in ABA metabolism was analyzed. Therefore, the expression level of genes involved in ABA biosynthesis and ABA perception were quantified during development of the fruit. Four NCED/CCDs and 6 PYR/PYLs family members were identified in F. chiloensis. Bioinformatics analyses confirmed the existence of key domains related to functional properties. Through RT-qPCR analyses the level of transcripts were quantified. FcNCED1 codifies a protein that displays crucial functional domains and...

Scientia Horticulturae, 2010

... Chandler) at three fruit developmental stages: large green (LG), turning (T) and ripe (R). A ... more ... Chandler) at three fruit developmental stages: large green (LG), turning (T) and ripe (R). A rapid decrease in fruit firmness between LG and T stages was observed in both species; nevertheless firmness reduction in F. chiloensis was steeper than in F. ×ananassa. ...

Postharvest Biology and Technology, 2004

The first noticeable event during the ripening of mountain papaya (Vasconcellea pubescens) is the... more The first noticeable event during the ripening of mountain papaya (Vasconcellea pubescens) is the rapid degreening of the skin, followed by climacteric ethylene and flesh softening. When ethylene perception is blocked by 1-methylcyclopropene (1-MCP, 0.3 l l −1 for 16 h at 20 • C), the increase in ethylene evolution is avoided, and softening and color development are partially delayed. This indicates that ethylene perception is an absolute requirement for ethylene production during ripening and that softening and color development are only partially dependent on ethylene. Our data also suggest that the changes in pH, titratable acidity, and soluble solids are not dependent on ethylene. Mountain papaya fruit displayed the typical climacteric rise in ethylene production, reaching maximum values of 1.8-3.2 mol kg −1 h −1 , and so confirmed the climacteric nature of the fruit. The activity of ACC oxidase paralleled changes in ethylene production. Nevertheless, when 1-MCP treated fruit recover ethylene sensitivity, a big increase in ACC oxidase activity is observed followed by a further increase, but at a reduced level, of ethylene; the reduced ACC content suggests that in these fruit the availability of ACC is limiting ethylene biosynthesis. Finally, our results indicate that treatment of mountain papaya with 1-MCP delays the onset of the climacteric phase, and therefore can be used commercially to extend effectively the short shelf life of this fruit.

Postharvest Biology and Technology, 2007

Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a stro... more Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a strong and characteristic aroma during ripening. The dynamics of aroma volatile production during ripening of whole papaya fruit were analysed by headspace-SPME. The main compounds produced by the fruit were esters (aliphatic and branched) and alcohols: the most abundant esters were ethyl acetate, ethyl butanoate, methyl butanoate and butyl acetate, comprising 88% of the volatiles in fully ripe fruit; butanol was the most abundant alcohol. Among the volatiles produced, ethyl butanoate, ethyl acetate, ethyl hexanoate and ethyl 2-methylbutanoate were found to be the most potent odour compounds. During ripening of mountain papaya fruit there was an increase in the total content of both esters and alcohols. In order to clarify the role of ethylene in aroma formation, mature fruit were treated with 0.3 L L −1 of 1-MCP (16 h at 20 • C) or with 2 g L −1 Ethrel, and then allowed to ripen at 20 • C. The treatment of the fruit with 1-MCP inhibited the rise in ethylene production in the fruit, while Ethrel advanced the development of the climacteric phase. Most esters identified in mountain papaya were dependent on ethylene, showing an increase in production during ripening and in response to Ethrel treatment, and a strong reduction in response to 1-MCP treatment. The data presented provide evidence that most esters produced by mountain papaya are derived from fatty acids and amino acid metabolic pathways, both of them being affected by ethylene.

Phytochemistry, 2010

Difference in fruit pigmentation observed between two botanical forms of Fragaria chiloensis ssp.... more Difference in fruit pigmentation observed between two botanical forms of Fragaria chiloensis ssp. chiloensis (form chiloensis and form patagonica) was studied through transcriptional and chemical approaches. The proportion of different anthocyanins was demonstrated to be characteristic of each botanical form, with pelargonidin 3-glucoside being the most abundant in f. patagonica fruit and cyaniding 3-glucoside as the major one in f. chiloensis fruit. Partial gene sequences of the phenylpropanoid and flavonoid biosynthesis pathways were isolated from the native Chilean strawberry fruits, and used to design gene-specific primers in order to perform transcriptional analyses by qRT-PCR. These genes showed spatial, developmental, and genotypic associated patterns. The red fruit of f. patagonica exhibited higher transcript levels of anthocyanin-related genes and higher levels of anthocyanins compared to the barely pigmented fruit of f. chiloensis. The anthocyanin accumulation in F. chiloensis ssp. chiloensis fruits was concomitant with the particular progress of the transcriptional activity of genes involved in the biosynthesis of flavonoid pigments. The differences in anthocyanin contents, both in terms of type and quantity, between the two botanical forms of F. chiloensis ssp. chiloensis were coincident with the differential transcriptional patterns found in the anthocyanin-related genes.

Phytochemistry, 2013

Anthocyanins and proanthocyanidins (PAs), flavonoid-derived metabolites with different physiologi... more Anthocyanins and proanthocyanidins (PAs), flavonoid-derived metabolites with different physiological roles, are produced by plants in a coordinated manner during fruit development by the action of transcription factors (TFs). These regulatory proteins have either an activating or repressing effect over structural genes from the biosynthetic pathway under their control. FaMYB1, a TF belonging to the R2R3-MYB family and isolated from commercial strawberry fruit (Fragaria×ananassa), was reported as a transcriptional repressor and its heterologous over-expression in tobacco flowers suppressed flavonoid-derived compound accumulation. FcMYB1, an ortholog of FaMYB1 isolated from the white Chilean strawberry (Fragaria chiloensis ssp. chiloensis f. chiloensis), showed higher transcript levels in white (F. chiloensis) than in red (F.×ananassa cv. Camarosa) fruits. In order to assess its contribution to the discolored phenotype in F. chiloensis, FcMYB1 was transiently down-regulated in planta using an RNAi-based approach. Quantitative real-time PCR on FcMYB1 down-regulated fruits resulted an up-regulation of anthocyanidin synthase (ANS) and a strong repression of anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR) transcript accumulation. In addition, these fruits showed increased concentrations of anthocyanins and undetectable levels of flavan 3-ols. Altogether, these results indicate a role for FcMYB1 in regulation of the branching-point of the anthocyanin/PA biosynthesis determining the discolored phenotype of the white Chilean strawberry fruit.

Journal of Plant Growth Regulation, 2012

Loss of verticality in conifers affects the normal wood development by inducing changes and chemi... more Loss of verticality in conifers affects the normal wood development by inducing changes and chemical modifications in tree stems called compression wood. It is known that ethylene influences the response during this abnormal wood-forming process. The expression pattern of genes involved in the ethylene biosynthesis pathway during gravitropic response in gymnosperms has been identified in adult trees. Young seedlings of radiata pine were inclined to reveal the expression pattern of these genes by the quantitative real-time PCR (qRT-PCR) technique. The seedlings were exposed to gravitropic stimuli and harvested after 2.5 and 10 h (early responses) of inclination, and after 24 h (late response). Sampling includes transverse cuts at three heights of the whole stem of inclined seedlings. Our data revealed that genes encoding for 1-aminocyclopropane-1-carboxylate oxidase (ACO) and 1-aminocyclopropane-1-carboxylate synthase (ACS) were differentially expressed during the time of leaning, and, interestingly, at the basal portion of radiata pine stems. Additionally, transcriptional analysis in maritime pine showed a conserved profile of gene activation in conifers, and in mature compression wood, ACO gene transcription was strongly upregulated. These results indicate that the concerted activation of genes involved in ethylene biosynthesis could be responding to leaning signals in young radiata and maritime pine seedlings.

Journal of Photochemistry and Photobiology B: Biology, 2010

Genetic analyses of Gnaphalium's DNA showed a high degree of polymorphism in UV-B irradiated plan... more Genetic analyses of Gnaphalium's DNA showed a high degree of polymorphism in UV-B irradiated plants when compared to controls. Among the five tested primers the four ISSR primers selected for this analysis generated a total of 189 fragments. A high proportion of polymorphic bands ranging from 70% to 28% were found using these ISSR markers. Nei and Li similarity indexes [1] were used to evaluate genetic divergence among plants. The dendrograms obtained using these markers efficiently separate plants from different treatments. A linear relationship was observed between UV-B dose and percentage of dissimilarity which may be related to DNA damage caused by the different UV-B treatments.

Journal of Molecular Graphics and Modelling, 2011

The aroma in fruits is an important attribute of quality that influences consumer's acceptance. T... more The aroma in fruits is an important attribute of quality that influences consumer's acceptance. This attribute is a complex character determined by a set of low molecular weight volatile compounds. In mountain papaya fruit (Vasconcellea pubescens) the aroma is determined mainly by esters, which are produced through an esterification reaction catalyzed by the enzyme alcohol acyltransferase (AAT) that utilizes alcohols and acyl-CoAs as substrates. In order to understand the molecular mechanism involved in the production of esters in this fruit, an AAT gene which has been previously cloned and characterized from mountain papaya (VpAAT1) was expressed in yeasts, and the highest enzyme activity of the recombinant protein was obtained when the enzyme was tested for its ability to produce benzyl acetate. On the other hand, to gain insight the mechanism of action at the molecular level, a structural model for VpAAT1 protein was built by comparative modelling methodology, which was validated and refined by molecular dynamics simulation. The VpAAT1 structure consists of two domains connected by a large crossover loop, with a solvent channel in the center of the structure formed between the two domains. Residues H166 and D170, important for catalytic action, displayed their side chains towards the central cavity of the channel allowing their interaction with the substrates. The conformational interaction between the protein and several ligands was explored by molecular docking simulations, and the predictions obtained were tested through kinetic analysis. Kinetic results showed that the lowest K M values were obtained for acetyl-CoA and benzyl alcohol. In addition, the most favorable predicted substrate orientation was observed for benzyl alcohol and acetyl CoA, showing a perfect coincidence between kinetic studies and molecular docking analysis.

Journal of Chemical Information and Modeling, 2013

Aroma in Vasconcellea pubescens fruit is determined by esters, which are the products of catalysi... more Aroma in Vasconcellea pubescens fruit is determined by esters, which are the products of catalysis by alcohol acyltransferase (VpAAT1). VpAAT1 protein structure displayed the conserved HxxxD motif facing the solvent channel in the center of the structure. To gain insight into the role of these catalytic residues, kinetic and site-directed mutagenesis studies were carried out in VpAAT1 protein. Based on dead-end inhibition studies, the kinetic could be described in terms of a ternary complex mechanism with the H166 residue as the catalytic base. Kinetic results showed the lowest Km value for hexanoyl-CoA. Additionally, the most favorable predicted substrate orientation was observed for hexanoyl-CoA, showing a coincidence between kinetic studies and molecular docking analysis. Substitutions H166A, D170A, D170N, and D170E were evaluated in silico. The solvent channel in all mutant structures was lost, showing large differences with the native structure. Molecular docking and molecular dynamics simulations were able to describe unfavored energies for the interaction of the mutant proteins with different alcohols and acyl-CoAs. Additionally, in vitro site-directed mutagenesis of H166 and D170 in VpAAT1 induced a loss of activity, confirming the functional role of both residues for the activity, H166 being directly involved in catalysis.

Journal of Agricultural and Food Chemistry, 2010

Mountain papaya ( Vasconcellea pubescens ) is a climacteric fruit that develops a strong and char... more Mountain papaya ( Vasconcellea pubescens ) is a climacteric fruit that develops a strong and characteristic aroma during ripening. Esters are the main volatile compounds produced by the fruit, and most of them are dependent on ethylene. As esters are synthesized through alcohol acyltransferases (AAT), a full-length cDNA (VpAAT1) was isolated that displayed the characteristic motifs of most plant acyltransferases. The full-length cDNA sequence was cloned and expressed in yeasts, obtaining a functional enzyme with high AAT activity toward the formation of benzyl acetate. The transcript accumulation pattern provided by qPCR analysis showed that the VpAAT1 gene is expressed exclusively in fruit tissues and that a high level of transcripts is accumulated during ripening. The increase in VpAAT1 transcripts in fruit is coincident with the increase in AAT activity; transcript accumulation is induced by ethylene, and it is avoided by 1-methylcyclopropene (1-MCP) treatment. The data indicate that VpAAT1 is involved in aroma formation and that ethylene plays a major role in regulating its expression.

Botany, 2008

Gomortega keule (Molina) Baillon is a rare Chilean species classified as endangered and currently... more Gomortega keule (Molina) Baillon is a rare Chilean species classified as endangered and currently under conservation. Currently, conservation of this species is carried out by private companies and government agencies, but is done so based more on pragmatic criteria than scientifically based strategies. In this context, information concerning the genetic variability of the species among the different populations over its entire distribution range is incomplete, making it difficult to coordinate management and conservation strategies. Here we report a study to evaluate the genetic variability and population structure of G. keule over its entire distribution in Chile. Twenty-five ISSR primers for 223 individuals from 11 geographical populations were tested to evaluate genetic variability. Results showed a high level of genetic diversity for the species. A high level of genetic differentiation among populations was found, while genetic structure of the geographic populations was also s...

BMC Plant Biology, 2010

Background Plants are subjected to continuous stimuli from the environment and have evolved an ab... more Background Plants are subjected to continuous stimuli from the environment and have evolved an ability to respond through various growth and development processes. Phototropism and gravitropism responses enable the plant to reorient with regard to light and gravity. Results We quantified the speed of maritime pine seedlings to reorient with regard to light and gravity over 22 days. Seedlings were inclined at 15, 30 and 45 degrees with vertical plants as controls. A lateral light source illuminated the plants and stem movement over time was recorded. Depending on the initial angle of stem lean, the apical response to the lateral light source differed. In control and 15° inclined plants, the apex turned directly towards the light source after only 2 h. In plants inclined at 30° and 45°, the apex first reoriented in the vertical plane after 2 h, then turned towards the light source after 24 h. Two-dimensional gel electrophoresis coupled with mass spectrometry was then used to describe ...

Biological Research, 2001

The identification and characterization of differential gene expression from tissues subjected to... more The identification and characterization of differential gene expression from tissues subjected to stress has gained much attention in plant research. The recognition of elements involved in the response to a particular stress enhances the possibility of promoting crop improvement through direct genetic modification. However, the performance of some of the 'first generation' of transgenic plants with the incorporation of a single gene has not always been as expected. These results have stimulated the development of new transgenic constructions introducing more than one gene and capable of modifying complex pathways. Several techniques are available to conduct the analysis of gene regulation, with such information providing the basis for novel constructs specifically designed to modify metabolism. This review deals with techniques that allow the identification and characterization of differentially-expressed genes and the use of molecular pathway information to produce transgenic plants.

Biologia Plantarum, 2013

ABSTRACT In conifers, relationship between ethylene and the response to inclination are not well ... more ABSTRACT In conifers, relationship between ethylene and the response to inclination are not well understood. The aim of this work was to study the consequence for the application of 2-chloroethyl phosphonic acid (ethephon), compound able to release ethylene, in one-year-old Pinus radiata D. Don seedlings subjected to inclination. In plants exposed to inclination for 15 d, increase in thickness of cell walls, more rounded shape of xylem cells, and accumulation of lignin were observed. Ethephon application accelerated significantly these changes; they can be observed after 5 d of inclination. The quantitative polymerase chain reaction (qPCR) showed up-regulation of transcripts from genes encoding phenylalanine ammonia lyase and cinnamyl alcohol dehydrogenase after inclination and their possible ethylene signal-dependence. As conclusion, morphological changes on stem xylem cells in young seedlings of radiata pine exposed to inclination are similar to those observed in compression wood and they are influenced by ethephon application.

Biodiversity and Conservation, 2005

Abstract. Gomortega keule (Molina) Baillon is an endangered, rare species, the only representativ... more Abstract. Gomortega keule (Molina) Baillon is an endangered, rare species, the only representative of its genus, and endemic to Central Chile. Populations of this tree are now fragmented and few individuals can be found in any of them. Genetic diversity was studied in 33 individuals ...

Biological Research, 2001

In 1995, when the entire DNA genome sequence of the first self-replicating organism, Haemophilus ... more In 1995, when the entire DNA genome sequence of the first self-replicating organism, Haemophilus influenzae, was described, the age of genomics was initiated. In the coming months and years the DNA sequences for different plant species will be delivered. In fact, within the last year ...

Journal of Photochemistry and …, 2010

Note to users: The section "Articles in Press" contains peer reviewed accepted articles... more Note to users: The section "Articles in Press" contains peer reviewed accepted articles to be published in this journal. When the final article is assigned to an issue of the journal, the "Article in Press" version will be removed from this section and will appear in the associated ...

Loss of verticality in conifers affects the normal wood development by inducing changes and chemi... more Loss of verticality in conifers affects the normal wood development by inducing changes and chemical modifications in tree stems called compression wood. It is known that ethylene influences the response during this abnormal wood-forming process. The expression pattern of genes involved in the ethylene biosynthesis pathway during gravitropic response in gymnosperms has been identified in adult trees. Young seedlings of radiata pine were inclined to reveal the expression pattern of these genes by the quantitative real-time PCR (qRT-PCR) technique. The seedlings were exposed to gravitropic stimuli and harvested after 2.5 and 10 h (early responses) of inclination, and after 24 h (late response). Sampling includes transverse cuts at three heights of the whole stem of inclined seedlings. Our data revealed that genes encoding for 1-aminocyclopropane-1-carboxylate oxidase (ACO) and 1-aminocyclopropane-1-carboxylate synthase (ACS) were differentially expressed during the time of leaning, and, interestingly, at the basal portion of radiata pine stems. Additionally, transcriptional analysis in maritime pine showed a conserved profile of gene activation in conifers, and in mature compression wood, ACO gene transcription was strongly upregulated. These results indicate that the concerted activation of genes involved in ethylene biosynthesis could be responding to leaning signals in young radiata and maritime pine seedlings.

Postharvest Biology and …, 2007

Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a stro... more Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a strong and characteristic aroma during ripening. The dynamics of aroma volatile production during ripening of whole papaya fruit were analysed by headspace-SPME. The main ...