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Álvaro Fonseca - One of the best experts on this subject based on the ideXlab platform.
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Genome Sequencing of the Plant Pathogen Taphrina deformans, the Causal Agent of Peach Leaf Curl
mBio, 2013Co-Authors: Ousmane H. Cissé, Philippe M. Hauser, João Almeida, Álvaro Fonseca, Ajay Anand Kumar, Jarkko Salojärvi, Kirk Overmyer, Marco PagniAbstract:Taphrina deformans is a fungus responsible for peach leaf curl, an important plant disease. It is phylogenetically as- signed to the Taphrinomycotina subphylum, which includes thefission yeast and the mammalian pathogens of the genus Pneu- mocystis. We describe here the genome of T. deformans in the light of its dual plant-saprophytic/plant-parasitic lifestyle. The 13.3-Mb genome contains few identifiable repeated elements (ca. 1.5%) and a relatively high GC content (49.5%). A total of 5,735 protein-coding genes were identified, among which 83% share similarities with other fungi. Adaptation to the plant host seems reflected in the genome, since the genome carries genes involved in plant cell wall degradation (e.g., cellulases and cutinases), secondary metabolism, the hallmark glyoxylate cycle, detoxification, and sterol biosynthesis, as well as genes involved in the bio- synthesis of plant hormones. Genes involved in lipid metabolism may play a role in its virulence. Several locus candidates for putative MAT cassettes and sex-related genes akin to those of Schizosaccharomyces pombe were identified. A mating-type- switching mechanism similar to that found in ascomycetous yeasts could be in effect. Taken together, thefindings are consistent with the alternate saprophytic and parasitic-pathogenic lifestyles of T. deformans. IMPORTANCE Peach leaf curl is an important plant disease which causes significant losses of fruit production. We report here the genome sequence of the causative agent of the disease, the fungus Taphrina deformans. The genome carries characteristic genes that are important for the plant infection process. These include (i) proteases that allow degradation of the plant tissues; (ii) secondary metabolites which are products favoring interaction of the fungus with the environment, including the host; (iii) hormones that are responsible for the symptom of severely distorted leaves on the host; and (iv) drug detoxification en- zymes that confer resistance to fungicides. The availability of the genome allows the design of new drug targets as well as the elaboration of specific management strategies tofight the disease.
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Taphrina fries 1832
The Yeasts (Fifth Edition), 2011Co-Authors: Álvaro Fonseca, Manuel G. RodriguesAbstract:Publisher Summary This chapter studies the genus Taphrina. In the determination of the asexual reproduction it is seen that yeast states grow in culture. Budding cells are present, and budding is frequently unipolar or bipolar. Cells are globose, ovoid, ellipsoidal, or cylindrical. Giant cells with thickened cell walls may be present in old cultures. Pseudohyphae may be formed. Cell walls are two-layered. Budding has been considered either holoblastic or enteroblastic; percurrent or sympodial elongation may occur, giving rise to distinct protrusions reminiscent of those found commonly in basidiomycetous yeasts. Colonies are cream, yellowish, or pinkish-cream but may become more intensely pink, orange, or tan upon aging. In sexual reproduction it is found that the filamentous states only form on host plants and give rise to asci that are primarily clavate to cylindrical and occur in a subcuticular palisade layer or are formed as terminal cells of the septate intercellular or subcuticular dikaryotic hyphae. In some species asci arise from more or less thick-walled ascogenous cells. In those cases a septum may form across the basal portion of the developing ascogenous cell, giving rise to the so-called stalk cell at the base of the ascus. Eight spherical, ovoid, ellipsoidal, or fusiform ascospores are formed and often bud inside the ascus, which becomes filled with smaller blastospores. Rupturing of the unitunicate ascus wall at the apex forcibly ejects ascospores and the entire content of the ascus is discharged as a single projectile. The chapter also discusses physiology/biochemistry and phylogenetic placement of the genus. The type species taken is Taphrina populina.
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Direct detection of Taphrina deformans on peach trees using molecular methods
European Journal of Plant Pathology, 2004Co-Authors: Sílvia Tavares, Álvaro Fonseca, Joao Inacio, Cristina OliveiraAbstract:The ascomycetous fungus Taphrina deformans is the agent of peach leaf curl, a worldwide disease of peach potentially devastating to both crop yields and tree longevity. Conspicuous leaf curl symptoms result from the invasion of host tissue by the strictly parasitic mycelial phase of the T. deformans dimorphic life-cycle. Successful isolation of the fungus in pure culture is cumbersome and limited to late spring/early summer (time of ascospore discharge from infected leaves) and only rarely has the asymptomatic yeast phase been isolated from buds. Molecular methods, namely those based on the hybridisation of nucleic acids, are advantageous for diagnostic purposes since they do not require isolation of the fungus on culture media. Direct amplification using the polymerase chain reaction (PCR) and fluorescent in situ hybridisation (FISH) were tested for diagnosis of peach leaf curl disease in order to provide a fast and reliable method for disease risk assessment. Specific primers and probes were designed based on available ribosomal DNA sequence data. Positive and specific diagnoses of peach leaf curl were achieved with primer TDITS1, using PCR-detection, and probe TDE634, using FISH, both on infected leaves and in washings of asymptomatic peach buds.
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characterisation and classification of phylloplane yeasts from portugal related to the genus Taphrina and description of five novel lalaria species
Fems Yeast Research, 2004Co-Authors: Joao Inacio, Manuel G. Rodrigues, Patricia Sobral, Álvaro FonsecaAbstract:Taphrina Fries is a genus of dimorphic ascomycetes comprising more than 90 species distinguished by the specific infections they produce on different vascular plants. Their filamentous states are restricted to parasitised plant tissue whereas the yeast states are saprobic and can be grown on artificial media. The latter coincide with the anamorphic phases and have been given separate nomenclatural status by the erection of the genus Lalaria R.T. Moore. In its original circumscription Lalaria included only 23 yeast states of known species of Taphrina and its creation was then redundant. Here we describe five novel species in the genus Lalaria to accommodate a total of 44 yeast isolates obtained mainly from leaf surfaces (phylloplane) of different plants in Portugal: Lalaria arrabidae sp. nov. (one strain), L. carpini sp. nov. (one strain), L. inositophila sp. nov. (37 strains), L. kurtzmanii sp. nov. (one strain) and L. veronaerambellii sp. nov. (four strains). L. inositophila was notable for its widespread occurrence since it was recovered during two consecutive years from the leaves of miscellaneous plant species. In the absence of sexual states and of unequivocal associations to particular host plants, the taxonomic relationship of the novel species to the yeast states of Taphrina available from culture collections was verified by the comparative analysis of physiological and molecular characteristics. The latter included PCR fingerprinting using single primers for microsatellite regions, sequencing of the 5′ end of the 26S rRNA (LSU) gene (D1/D2 domains) and of the ITS1 and ITS2 rDNA spacer regions, and DNA–DNA hybridisation experiments. An emended description of the genus Lalaria is provided.
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Phenotypic and genotypic identification and phylogenetic characterisation of Taphrina fungi on alder
Mycological Progress, 2003Co-Authors: Kamila Bacigálová, Álvaro Fonseca, Ksenija Lopandic, Manuel G. Rodrigues, Michael Herzberg, Wilhelm Pinsker, Hansjörg PrillingerAbstract:All Taphrina species are dimorphic with a mycelium stage biotrophic on vascular plants and a saprophytic yeast stage. European species of Taphrina on Alnus species (Betulaceae) were identified using morphological, physiological and molecular characteristics, the latter including determination of PCR fingerprints and of nucleotide sequences from selected nuclear ribosomal DNA regions. PCR fingerprinting gives a good overview of species identification, as do nucleotide sequences, which in addition, help to clarify phylogenetic relationships. Taphrina alni is a homogeneous species that exhibited more than 50% similarity in PCR fingerprinting with three different primers. Morphologically, it produces tongue-like outgrowths from female catkins of Alnus incana. Taphrina robinsoniana from A. rugosa and A. serrulata in North America is phylogenetically closely related to T. alni , but the two species could be separated by their PCR fingerprints, partial sequences of 26S rDNA (D1/D2) and ITS1/ITS2 sequences. T. epiphylla and T. sadebeckii are two phylogenetically closely related species. T. epiphylla causes witches brooms in crowns of A. incana . In addition, T. epiphylla forms slightly yellow white-grey leaf spots in midsummer on A. incana . Yellow white-grey leaf spots up to 10 mm on A. glutinosa are characteristic for T. sadebeckii . Both species can be separated well by PCR fingerprinting. Different from T. epiphylla, T. sadebeckii is genotypically more heterogeneous. Only two out of three different primers showed similarity values above 50% in different European strains of T. sadebeckii . Although genetic variability was not detected in complete sequences of the 18S ribosomal DNA of T. sadebeckii , ITS1/ITS2 sequences appeared to be more heterogeneous, too. Taphrina tosquinetii is a genotypically homogeneous species causing leaf curl on Alnus glutinosa . It was not possible to distinguish the yeast phases from different Taphrina species on Alnus using morphological and physiological characteristics only.
Simona Giosue - One of the best experts on this subject based on the ideXlab platform.
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influence of weather conditions on infection of peach fruit by Taphrina deformans
Phytopathology, 2007Co-Authors: Vittorio Rossi, Matteo Bolognesi, Simona GiosueAbstract:ABSTRACT The effect of environment on the infection of peach fruit by Taphrina deformans was investigated using orchard observations under natural conditions (in 2001 to 2004) or in trees managed in such a way to exclude rainfall. These conditions were then validated using pot-grown peach plants exposed to single infection events and independent orchard observations. Leaf curl incidence was related to rainfall, length of wet periods, and the temperature during wetness and during the incubation period, as well as to the developmental stage of flowers and fruit. Weather conditions before petal fall did not influence fruit infection. After petal fall, rainfall and the duration of the wet period triggered by rainfall played a key role in infection occurrence. The minimum rainfall required for infection was 12 mm, with at least 24 h of wetness interrupted by no more than 4 h. No infection occurred when temperature was ≥17°C during the wet period or >19°C during incubation. Disease symptoms appeared on fruit af...
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seasonal dynamics of Taphrina deformans inoculum in peach orchards
Phytopathology, 2007Co-Authors: Vittorio Rossi, Matteo Bolognesi, Simona GiosueAbstract:ABSTRACT The dynamics of the inoculum of Taphrina deformans were studied during a 4-year period by (i) inspecting curled leaves for the presence of asci, (ii) placing deposition spore samplers within the tree canopies, and (iii) exposing potted peach plants (trap plants). These three approaches produced consistent results. Four main periods characterized the dynamics of the inoculum: the first period coincides with the parasitic stage of the pathogen's life cycle and the other periods with the saprophytic stage. Mid- to late spring (first period) was characterized by the presence of asci on infected leaves which produced and ejected large quantities of ascospores in 96% of the samplings. Rainfall was not necessary for ascospore dispersal, which was favored by air temperature /=80% or wetness duration >8 h. In summer and autumn (second period), blastospores were trapped in 54 and 24% of samplings, respectively, with low spore numbers. In the winter (third period), blasto-spores were trapped in the lowest numbers and in only 6% of samplings. In late winter to early spring (fourth period), blastospores were found in 56% of samples, with increasing numbers. Rainfall significantly influenced blastospore dispersal and temperature was correlated with the seasonality found during the saprophytic stage.
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influence of environmental conditions on infection of peach shoots by Taphrina deformans
Phytopathology, 2006Co-Authors: Vittorio Rossi, Matteo Bolognesi, Luca Languasco, Simona GiosueAbstract:ABSTRACT The effect of weather conditions on the infection of peach shoots by Taphrina deformans was investigated both under orchard conditions and in controlled-environment experiments. Leaf curl incidence and severity were related to rainfall, length of wet periods, and temperature during wetness and during the incubation period, as well as to the development stage of shoots. Surface wetness was more important than rainfall for infection to occur. Minimum rainfall for infection was 3 mm, with a wet period of at least 12.5 h; higher amounts of rainfall did not cause infection when the wet period they triggered was shorter. Wet periods initiated by dew or fog were too short for infection to occur. Infection occurred only when air temperature was <16°C during the wet period and <19°C during incubation. Logistic equations relating relative disease incidence and either duration of wetness or temperature were developed under controlled-environment conditions, with asymptotes at ≥48 h of wetness and ≤8°C for t...
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forecasting infections of the leaf curl disease on peaches caused by Taphrina deformans
European Journal of Plant Pathology, 2000Co-Authors: Simona Giosue, Vittorio Rossi, G Spada, G Carli, I PontiAbstract:An Israeli model forecasting leaf curl disease on peaches caused by Taphrina deformans was validated in the Emilia-Romagna region of northern Italy, during a three-year period (1996–1998), in 13 cases (year × location × cultivar). When the peach trees are susceptible to infection, the model uses mathematical functions to calculate the risk of infection on the basis of weather conditions (daily rainfall greater than 10 mm, and maximum air temperature greater than 5°C), and it forecasts periods of possible symptom appearance based on the length of incubation. Peach trees became susceptible to infection between the end of January and mid March, when the first leaf buds attained phenological stage C, i.e. appearance of leaf apex. The trees remained susceptible for at least 9 weeks: the last infection occurred in mid-May.
Vittorio Rossi - One of the best experts on this subject based on the ideXlab platform.
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influence of weather conditions on infection of peach fruit by Taphrina deformans
Phytopathology, 2007Co-Authors: Vittorio Rossi, Matteo Bolognesi, Simona GiosueAbstract:ABSTRACT The effect of environment on the infection of peach fruit by Taphrina deformans was investigated using orchard observations under natural conditions (in 2001 to 2004) or in trees managed in such a way to exclude rainfall. These conditions were then validated using pot-grown peach plants exposed to single infection events and independent orchard observations. Leaf curl incidence was related to rainfall, length of wet periods, and the temperature during wetness and during the incubation period, as well as to the developmental stage of flowers and fruit. Weather conditions before petal fall did not influence fruit infection. After petal fall, rainfall and the duration of the wet period triggered by rainfall played a key role in infection occurrence. The minimum rainfall required for infection was 12 mm, with at least 24 h of wetness interrupted by no more than 4 h. No infection occurred when temperature was ≥17°C during the wet period or >19°C during incubation. Disease symptoms appeared on fruit af...
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seasonal dynamics of Taphrina deformans inoculum in peach orchards
Phytopathology, 2007Co-Authors: Vittorio Rossi, Matteo Bolognesi, Simona GiosueAbstract:ABSTRACT The dynamics of the inoculum of Taphrina deformans were studied during a 4-year period by (i) inspecting curled leaves for the presence of asci, (ii) placing deposition spore samplers within the tree canopies, and (iii) exposing potted peach plants (trap plants). These three approaches produced consistent results. Four main periods characterized the dynamics of the inoculum: the first period coincides with the parasitic stage of the pathogen's life cycle and the other periods with the saprophytic stage. Mid- to late spring (first period) was characterized by the presence of asci on infected leaves which produced and ejected large quantities of ascospores in 96% of the samplings. Rainfall was not necessary for ascospore dispersal, which was favored by air temperature /=80% or wetness duration >8 h. In summer and autumn (second period), blastospores were trapped in 54 and 24% of samplings, respectively, with low spore numbers. In the winter (third period), blasto-spores were trapped in the lowest numbers and in only 6% of samplings. In late winter to early spring (fourth period), blastospores were found in 56% of samples, with increasing numbers. Rainfall significantly influenced blastospore dispersal and temperature was correlated with the seasonality found during the saprophytic stage.
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influence of environmental conditions on spore production and budding in Taphrina deformans the causal agent of peach leaf curl
Phytopathology, 2007Co-Authors: Vittorio Rossi, Luca LanguascoAbstract:ABSTRACT Environment-controlled studies were carried out to determine the growth of Taphrina deformans under different conditions of temperature, humidity, and nutrient availability similar to those found on plant surfaces during the peach-growing season. Both ascospores and blastospores were able to bud at all temperatures tested (5 to 37 degrees C), with the optimum at 14 and 21 degrees C, respectively. Temperature <20 degrees C favored ascospore production and release, with the optimum at 10 degrees C. Budding was approximately two-and-a-half times higher in a film of water than on a dry substrate, with 100% relative humidity and blastospores also maintained a certain budding ability at lower humidity levels (minimum tested = 47%). Both spore types did not bud after approximately 50 to 55 h in the absence of external nutrients. In the presence of a periodically renewed carbon source, such as simple sugars, at concentrations that typically are present on peach plant surfaces, the fungus maintained its budding capability over time. Results showed that T. deformans is able to bud profusely under a wide range of environmental conditions that occur on peach tree surfaces. This work supports the hypothesis that T. deformans is a part of the normal epiphytic mycoflora of peach trees throughout the entire growing season.
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influence of environmental conditions on infection of peach shoots by Taphrina deformans
Phytopathology, 2006Co-Authors: Vittorio Rossi, Matteo Bolognesi, Luca Languasco, Simona GiosueAbstract:ABSTRACT The effect of weather conditions on the infection of peach shoots by Taphrina deformans was investigated both under orchard conditions and in controlled-environment experiments. Leaf curl incidence and severity were related to rainfall, length of wet periods, and temperature during wetness and during the incubation period, as well as to the development stage of shoots. Surface wetness was more important than rainfall for infection to occur. Minimum rainfall for infection was 3 mm, with a wet period of at least 12.5 h; higher amounts of rainfall did not cause infection when the wet period they triggered was shorter. Wet periods initiated by dew or fog were too short for infection to occur. Infection occurred only when air temperature was <16°C during the wet period and <19°C during incubation. Logistic equations relating relative disease incidence and either duration of wetness or temperature were developed under controlled-environment conditions, with asymptotes at ≥48 h of wetness and ≤8°C for t...
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forecasting infections of the leaf curl disease on peaches caused by Taphrina deformans
European Journal of Plant Pathology, 2000Co-Authors: Simona Giosue, Vittorio Rossi, G Spada, G Carli, I PontiAbstract:An Israeli model forecasting leaf curl disease on peaches caused by Taphrina deformans was validated in the Emilia-Romagna region of northern Italy, during a three-year period (1996–1998), in 13 cases (year × location × cultivar). When the peach trees are susceptible to infection, the model uses mathematical functions to calculate the risk of infection on the basis of weather conditions (daily rainfall greater than 10 mm, and maximum air temperature greater than 5°C), and it forecasts periods of possible symptom appearance based on the length of incubation. Peach trees became susceptible to infection between the end of January and mid March, when the first leaf buds attained phenological stage C, i.e. appearance of leaf apex. The trees remained susceptible for at least 9 weeks: the last infection occurred in mid-May.
Marco Pagni - One of the best experts on this subject based on the ideXlab platform.
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Genome Sequencing of the Plant Pathogen Taphrina deformans, the Causal Agent of Peach Leaf Curl
mBio, 2013Co-Authors: Ousmane H. Cissé, Philippe M. Hauser, João Almeida, Álvaro Fonseca, Ajay Anand Kumar, Jarkko Salojärvi, Kirk Overmyer, Marco PagniAbstract:Taphrina deformans is a fungus responsible for peach leaf curl, an important plant disease. It is phylogenetically as- signed to the Taphrinomycotina subphylum, which includes thefission yeast and the mammalian pathogens of the genus Pneu- mocystis. We describe here the genome of T. deformans in the light of its dual plant-saprophytic/plant-parasitic lifestyle. The 13.3-Mb genome contains few identifiable repeated elements (ca. 1.5%) and a relatively high GC content (49.5%). A total of 5,735 protein-coding genes were identified, among which 83% share similarities with other fungi. Adaptation to the plant host seems reflected in the genome, since the genome carries genes involved in plant cell wall degradation (e.g., cellulases and cutinases), secondary metabolism, the hallmark glyoxylate cycle, detoxification, and sterol biosynthesis, as well as genes involved in the bio- synthesis of plant hormones. Genes involved in lipid metabolism may play a role in its virulence. Several locus candidates for putative MAT cassettes and sex-related genes akin to those of Schizosaccharomyces pombe were identified. A mating-type- switching mechanism similar to that found in ascomycetous yeasts could be in effect. Taken together, thefindings are consistent with the alternate saprophytic and parasitic-pathogenic lifestyles of T. deformans. IMPORTANCE Peach leaf curl is an important plant disease which causes significant losses of fruit production. We report here the genome sequence of the causative agent of the disease, the fungus Taphrina deformans. The genome carries characteristic genes that are important for the plant infection process. These include (i) proteases that allow degradation of the plant tissues; (ii) secondary metabolites which are products favoring interaction of the fungus with the environment, including the host; (iii) hormones that are responsible for the symptom of severely distorted leaves on the host; and (iv) drug detoxification en- zymes that confer resistance to fungicides. The availability of the genome allows the design of new drug targets as well as the elaboration of specific management strategies tofight the disease.
Vittorio Raggi - One of the best experts on this subject based on the ideXlab platform.
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co2 assimilation respiration and chlorophyll fluorescence in peach leaves infected by Taphrina deformans
Physiologia Plantarum, 1995Co-Authors: Vittorio RaggiAbstract:Photosynthesis, respiration and chlorophyll fluorescence parameters were determined in peach (Prunus persica L. cv. Dixired) leaves naturally infected by Taphrina deformans (Berk.) Tul. and in healthy leaves (controls), in two successive springs. A drastic decrease in net photosynthesis and an evident increase in respiration in curled leaves were noted. The instantaneous PSII fluorescence yield, with no (F o ) and with (F o ) quenching component, and steady state fluorescence yield (under actinic light, F s ) were essentially unchanged. Maximal fluorescence in dark-adapted (F m ) and illuminated (F m ) leaves and the corresponding variable fluorescence (F v and F v ') clearly decreased. The indicators of PSII quantum yield (F v /F m ) in dark-adapted leaves, and the potential PSII excitation capture efficiency (F v '/F m ') and the quantum yield of PSII (q p [F v '/F m ']) in the light were also significantly lower in curled leaves. Decreasing tendencies were also noted for the PSII photochemical yield (photochemical quenching, q p ) and in the energy status of the chloroplast (non-photochemical quenching, q N , and Stern-Vollmer value, NPQ) although the differences were not always significant. In curled leaves the main alteration documented is the imbalance between the drastic inhibition of CO 2 fixation and the moderate decrease in photochemical reactions (i.e. F v /F m and ΔF/F m ' indicating changes in the energy flux
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gas exchange and carbon balance in peach leaves infected by Taphrina deformans
Plant Science, 1994Co-Authors: Vittorio RaggiAbstract:Abstract Gas exchange was investigated in peach ( Prunus persica L.) leaves, naturally infected by Taphrina deformans (Berk.) Tul, in an attempt to clarify the mechanism(s) of carbon balance. Photosynthesis, respiration, glycolysis, intercellular CO 2 , CO 2 release in the light in CO 2 -free air, CO 2 burst and CO 2 compensation point were measured in freshly detached leaves at 21%, 2% and 100% O 2 , using a CO 2 infrared gas analyser. Photosynthesis was also determined in the field (non-detached leaves) by a portable open gas exchange system, which also measured transpiration and calculated intercellular CO 2 . A striking decrease in net photosynthesis, in the light/dark CO 2 release ratio and lack of CO 2 burst were documented in curled leaves, compared to controls. An evident increase in respiration, CO 2 release in the light in CO 2 -free air (particularly at 2% O 2 ), intercellular CO 2 concentrations and a steep rise in the CO 2 compensation point were also noted. Refixation of the CO 2 produced by stimulated respiration (apparently not inhibited in the light) may account for part of the net photosynthetic inhibition. High intercellular CO 2 concentration, lack of CO 2 burst, scarce O 2 sensitivity by photosynthesis and illuminated leaf CO 2 release in CO 2 -free air have been considered indicators of weak photorespiration in curled leaves. Gas exchange unbalance (i.e. CO 2 release by illuminated leaves) seems to be responsible for the rise in the intercellular CO 2 concentration, the marked increase in the CO 2 compensation point and would imply great heterotrophy in curled leaves.