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Rust severity in plants inoculated with Puccinia psidii. a Rust severity in resistant inoculated plants was virtually null with only small fleck symptoms seen at 20 DAI, b rust severity in susceptible plant 4 DAI (2% DLA on average), c rust severity in susceptible plant 8 DAI (12% DLA on average), d rust severity in susceptible plant 12 DAI (16% DLA on average), e rust severity in susceptible plant 16 DAI (20% DLA on average) and f rust severity in susceptible plant 20 DAI (42% DLA on average). Noninoculated plants showed no sign of infection
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One of the most important diseases of eucalyptus plantations is caused by the rust fungus Puccinia psidii. While the genetic basis of rust resistance has been addressed recently, little is known about the physiological aspects
of Eucalyptus–P. psidii interaction. In order to fill this gap, we undertook a study investigating the effects of P. psidii...
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... It is notably comparable to the values reported for E. globulus (68.5 μg g 1 h 1 ), E. grandis (61.1 μg g 1 h 1 ), and E. rudis (61.4 μg g 1 h 1 ) by He et al. (2000). Analysis of physiological parameters and LMA for the 114 individuals revealed lognormal or normal distributions ( Figure S2 in Supporting Information S1), with ranges aligning with previously reported values for eucalyptus (Alves et al., 2011;Carignato et al., 2019;Cha-um et al., 2013;Chen et al., 2018;Chen et al., 2020;J. R. Evans, 2009;Hua et al., 2021;Novriyanti et al., 2020;Wu et al., 2014;Yang et al., 2018). ...
Accurately measuring emission factors (Es) of biogenic volatile organic compounds (BVOCs) with consideration of intraspecific variability is vital but often overlooked. This study presents in‐situ measurements of BVOC emissions from 114 Eucalyptus urophylla individuals using the LI‐6800 portable photosynthesis system. We observed intraspecific variability exceeding an order of magnitude in BVOC Es. Despite this variability, our approach yielded statistically representative Es for E. urophylla, yet challenging the feasibility of extensive field measurements. By quickly screening net photosynthesis rate (Pn) across a broad set of individuals and selecting those within a specific Pn range, such as mean ± 0.1 × SD (standard deviation) of Pn for all screened individuals, for detailed BVOC emission measurements, we achieved comparable mean Es with approximately 10% of the original sampling effort. This offers a practical solution for efficient and accurate field measurement of representative BVOC Es, significantly reducing required sample size while effectively addressing intraspecific variability.
... On the other hand, studies have reported that the damage caused by pathogens on leaves led to significant reductions in the net CO 2 assimilation rate (A), stomatal closed (g s ), and transpiration rate (E), as well as alteration in plant water balance and foliar temperature [7,8,52,[58][59][60]. In the case of biotrophic fungi as Hemileia vastatrix, Austropuccinia psidii, and Phakopsora pachyrhizi infecting coffee, eucalyptus, and soybean, respectively, after evidencing symptoms, experiments have demonstrated reductions between 20 and 50% in A, while g s and E showed higher reductions than A in leaves with severity oscillated between 30 and 50% [45,61,62]. ...
Plant diseases are a major threat to food security, causing drastic alterations in plant metabolism upon infection by pathogens. This often results in decreased biomass accumulation, slowed growth rates, and diminished yield components. Pathogens, through various lifestyles such as biotrophic, necrotrophic, and hemibio-trophic, disrupt photosynthesis, the primary metabolic process, via functional and structural damages. Furthermore, the CO 2 assimilation in plants is severely altered by pathogens regardless of their lifestyles. Photosynthetic determinations allow us to establish a perspective about the physiological impairment caused by pathogens related to alterations in the CO 2 flow from the atmosphere to carboxylation sites, stomatal limitations, and photosynthetic performance of photosystem II (PSII). From the changes in the energy, dissipation is possible to establish the functional status of the photochemistry machinery under stress conditions. For the above, chlorophyll a fluorescence (CF) and CF imaging (CFI) arose as a method highly sensible to determine the damage caused by pathogens in plants. This review shows a practical perspective on CF tools using visual method and rapid fluorescence induction kinetics (OJIP-test), for disease detection associated with plant-pathogen interaction studies from the physiological viewpoint, their implications for plant pathology research, applications for the plant phenotyping field, and biotic stress detection.
... On the other hand, studies have reported that the damage caused by pathogens on leaves led to significant reductions in the net CO 2 assimilation rate (A), stomatal closed (g s ), and transpiration rate (E), as well as alteration in plant water balance and foliar temperature [7,8,52,[58][59][60]. In the case of biotrophic fungi as Hemileia vastatrix, Austropuccinia psidii, and Phakopsora pachyrhizi infecting coffee, eucalyptus, and soybean, respectively, after evidencing symptoms, experiments have demonstrated reductions between 20 and 50% in A, while g s and E showed higher reductions than A in leaves with severity oscillated between 30 and 50% [45,61,62]. ...
Plant diseases are a major threat to food security, causing drastic alterations in plant metabolism upon infection by pathogens. This often results in decreased biomass accumulation, slowed growth rates, and diminished yield components. Pathogens, through various lifestyles such as biotrophic, necrotrophic, and hemibio-trophic, disrupt photosynthesis, the primary metabolic process, via functional and structural damages. Furthermore, the CO 2 assimilation in plants is severely altered by pathogens regardless of their lifestyles. Photosynthetic determinations allow us to establish a perspective about the physiological impairment caused by pathogens related to alterations in the CO 2 flow from the atmosphere to carboxylation sites, stomatal limitations, and photosynthetic performance of photosystem II (PSII). From the changes in the energy, dissipation is possible to establish the functional status of the photochemistry machinery under stress conditions. For the above, chlorophyll a fluorescence (CF) and CF imaging (CFI) arose as a method highly sensible to determine the damage caused by pathogens in plants. This review shows a practical perspective on CF tools using visual method and rapid fluorescence induction kinetics (OJIP-test), for disease detection associated with plant-pathogen interaction studies from the physiological viewpoint, their implications for plant pathology research, applications for the plant phenotyping field, and biotic stress detection.
... Pathogens can penetrate the leaf through either the stomata or the cuticle, but our histological observations revealed that A. psidii had no affinity with the stomata, suggesting that changes in stomatal dynamics do not occur due to pathogen penetration. This fact is supported by other studies, where changes in leaf gas exchange did not occur soon after A. psidii infection [9,44]. The decrease in gas exchange occurs soon after the onset of rust symptoms, showing that changes in stomatal dynamics may be linked to pathogen colonisation in the substomatal chamber of guava leaves. ...
This study aimed to characterise the life cycle of Austropuccinia psidii, the causal agent of myrtle rust, in guava cv. Paluma and to determine how this pathogen affects gas exchange in diseased leaves. The pathogen formed appressoria on ordinary epidermal cells and intercellular hyphae and intracellular branched lobe-shaped haustoria in parenchyma cells. In the stem, hyphae grew in the cortical region and crossed between tracheary cells, reaching the medullary region. In the leaf, hyphae colonised the intercellular spaces of the main vein and mesophyll and the substomatal chamber. Colonisation of the substomatal chamber by A. psidii changed the stomatal dynamics and leaf gas exchange. The stomatal response to light was slower and had a smaller amplitude in diseased guava leaves. Consequently, impaired stomatal movement induced by A. psidii is an additional factor changing the performance of plants under abiotic stress.
... On the contrary, it was also reported that plant photosynthesis increased after disease stress, such as in soybean (Glycine max) infected with the soybean mosaic virus Sg strain (Lu and Chen 1992). On the other hand, other studies had shown that there was no significant change in plant photosynthesis after disease stress, such as in eucalyptus (Eucalyptus robusta) infected with rust (Alves et al. 2011). These contradictory results forced researchers to conduct in-depth research on stomatal conductance and photosynthetic system and found that the relationship between disease and plant photosynthesis was affected by many factors. ...
... However, more studies showed that the infection of pathogenic fungi significantly inhibited the opening of stomata of host plants, resulting in the decrease of stomatal conductance of pine (Pinus) and Alaska shrubs (Rohrs-Richey et al. 2011, Hubbard et al. 2013, Aguadé et al. 2015. After eucalyptus (Eucalyptus robusta) was infected with rust (Alves et al. 2011), sugarcane (Saccharum officinarum) was infected with citrus rust (Zhao et al. 2011), and pea (Pisum sativum) was infected with pea mosaic virus (Kyseláková et al. 2011), the stomatal conductance of leaves decreased in a short time. At present, there was a great controversy about the maximal quantum yield of PSII photochemistry (Fv/Fm) by diseases. ...
... Olinda) infected with green spot algae (Wang et al. 2006), douglas pine (Pinus douglasiana) infected with fungi (Manter 2002), loquat (Eriobotrya japonica) infected with anthracnose (Zheng 2001), chestnut (Castanea mollissima) infected with Phytophthora, and zucchini (Cucurbita pepo) infected with silverleaf disease (Hao et al. 2009, Dinis et al. 2011. It had also been reported that the Fv/Fm did not change after the infection of diseases, such as in tobacco (Nicotiana tabacum) infected with tobacco mosaic virus (Dinis et al. 2011) and eucalyptus (Eucalyptus robusta) infected with rust (Alves et al. 2011). ...
To clarify the effect of leaf scorch on walnut leaf photosynthesis, photosynthetic parameters were measured in Juglans regia 'Wen185' and 'Xinxin2' symptom trees (WS, XS) and symptomless trees (WH, XH). At the early stage of infection and under the low-grade leaf scorch, WS showed significantly lower net photosynthetic rate (PN), stomatal limitation (Ls), and higher intercellular CO2 concentration (Ci) than those of WH. However, at the mid to late stage of infection and under the high-grade leaf scorch, WS showed significantly lower PN, Ci, the maximal quantum yield of PSII photochemistry and higher Ls, minimal fluorescence yield of the dark-adapted state, nonphotochemical quenching than those of WH, which would occur once Juglans regia 'Xinxin2' was infected. The above results indicated the effect of leaf scorch on walnut leaf photosynthesis was related to the walnut varieties and the duration and severity of the disease. Under the influence of leaf scorch, the decline in photosynthesis of Juglans regia 'Wen185' leaves changed from stomatal to nonstomatal restriction, while Juglans regia 'Xinxin2' leaves showed always nonstomatal restriction.
... This fungus is found on plant parts younger than two years [10], such as leaf primordia, young leaves and petiole. It causes necrosis and deformation of tissues with yellowish pustules in highly susceptible hosts [12][13][14]. Austropuccinia psidii generally penetrates directly through the cuticle and epidermis by appressorium [1,15,16]. However, the entrance, establishment and reproduction of this fungus gradually decrease with the Eucalyptus leaf age [15,17]. ...
The fungus Austropuccinia psidii infects young tissues of Eucalyptus plants until they are two years old in the nursery and field, causing Myrtaceae rust. The characteristics making older eucalypt leaves resistant to A. psidii and the reason for the low levels of this pathogen in older plants need evaluations. The aim of this study was to evaluate the morphological differences between Eucalyptus grandis leaves of different growth stages and two plant ages to propose a visual phenological scale to classify E. grandis leaves according to their maturation stages and to evaluate the time of leaf maturation for young and adult plants. A scale, based on a morphological differentiation for E. grandis leaves, was made. The color, shape and size distinguished the leaves of the first five leaf pairs. Anatomical analysis showed a higher percentage of reinforced tissue, such as sclerenchyma-like tissue and collenchyma, greater leaf blade thickness, absence of lower palisade parenchyma in the mature leaves and a higher number of cavities with essential oils than in younger ones. Changes in anatomical characteristics that could reduce the susceptibility of older E. grandis leaves to A. psidii coincide with the time of developing leaf resistance. Reduced infection of this pathogen in older plants appears to be associated with a more rapid maturation of their leaf tissues.
... The generally known fact is that leaf diseases may have destructive effect on the photosynthesis and gas exchange and can sharply reduce photosynthesis in different crop plants [16]. Pathogens cause morphological, physiological and biochemical changes, as the significant decrease in the amount of photosynthetic pigments, and thus restrict the photosynthesis rate and, resulting from it, reduce the capacity of the assimilation apparatus [17][18][19]. Following the plant tissues infection, many pathogens may impair photosynthesis even in the initial stage of an infection before any symptoms are visible [20,21]. ...
... In the majority of diseases, the photosynthesis rate may be reduced at the beginning of the infection. Indeed, most pathogens decreased their photosynthesis levels from the onset of infection even though there were no visible symptoms [19,20,28]. ...
... The investigations of Bispo et al. [28] have confirmed that Ceratocystis fimbriata isolates caused the decrease in stomatal conductance independently of the mango variety, and therefore simultaneously they cause a diffusive limitation of the assimilation of CO 2 . It was proved that the reduced level of Gs is the one of major limitations of photosynthesis in infected plants by lowering the availability of the CO 2 flow by the leaf area [19]. The research of Ribeiro et al. [29] is concur with ours and shows that the factors of the CO 2 assimilation and stomatal conductance (Gs) were higher on the healthy seedlings of orange than on those infested by Xylella fastidiosa. ...
Recently, the ecological awareness of society and the need to take care of our surroundings and the natural environment has significantly increased. There is also an urgent problem of searching for new, environmentally friendly techniques for its purification (soil, ground and surface waters, sewage sludge and air) with the use of living organisms, especially higher plants. One plant species investigated for phytoremediation is canna. Ten varieties of canna, grown on degraded and garden soil, were tested in this respect. The disease index and species composition of fungi inhabiting its organs, growth dynamics, parameters of photosynthesis and gas exchange were determined. The conducted research showed that cannas are able to satisfactorily grow even in seemingly unfavorable soil conditions with its strong degradation. Among a total of 24 species of fungi obtained from its organs, genus Fusarium, considered as pathogenic for canna, Alternaria alternata, and, less frequently, Thanatephorus cucumeris and Botrytis cinerea, dominated. The cultivars ‘Picasso’, ‘Cherry Red’, ‘President’ and ‘La Boheme’ had lower rates of photosynthesis and gas exchange than the least affected ‘Botanica’, ‘Wyoming’, ‘Robert Kemp’ and ‘Lucifer’ cultivars. Those turned out to be the most beneficial and they can be recommended for cultivation on strongly degenerated soils.
... The control plants of both resistant and susceptible genotypes showed no significant changes in transpiration rate. The findings of the study are in accordance with the previous studies (Kumar et al., 2013;Alves et al., 2011;Resende et al., 2012). ...
Rice is the one main source of nutrition for a larger part of world population but a significant proportion of rice production is lost every year due to various and biotic stress factors. Bakanae disease is an emerging and serious threat to rice production and the remedies are needed of the bakanae disease otherwise it can be a destructive disease. The leaf gas exchange activities are seriously affected by any stress to normal plants. In present study the impact of bakanae disease on various leaf gas exchange activities of rice in two contrasting (resistant & susceptible) genotypes was studied. It was observed that pathogen inoculation inhibited the germination, increased the plant height and decreased the root length in susceptible genotype with no significant changes in resistant genotype. The leaf gas exchange activities were was initially increased in inoculated plants but later it was decreasing as compared to control. The reduction was very high in susceptible genotype with very less reduction in resistant genotype. No significant changes were observed in any activity in control plants of both genotypes at each time interval.
... However, despite the reduction in these parameters, there was no significant variation in Ci (vpm). According to Alves et al. (2011), a lower A should not only be associated with the lower entry of CO 2 in the leaves, but with some biochemical limitation in the fixation of CO 2 within the chloroplasts. The increase in A μmol m -2 s -1 and the invariability of Ci were similar to data obtained from seedlings in mangrove areas affected by the tailings plume from the Fundão dam (RRDM, 2020). ...
Iron is an essential element, and its deficiency and excess result in negative effects on the growth and physiology of plants. Heavy metals are the highest anthropic pollutants that affect mangrove ecosystem. This study aimed to analyze the development of Rhizophora mangle seedlings in response to excess Fe under controlled conditions. Seedlings of R. mangle previously established were transferred to the culture substrate containing 45 (Control), 135, 225, 270, and 315 µmol L-1 of Fe. The propagules were cultivated for 270 days and during this period the epicotyl length and leaf production were evaluated. At the end of the experiment, the epicotyl length, growth rate, and gas exchange of the seedlings were calculated in the different treatments and the quantification of Fe in the aerial part and root of the seedlings were performed. The excess of Fe led to lower incorporation of biomass, mainly affecting leaf production in the treatment with 315 µmol L-1. A reduction was observed in the assimilation of carbon, also a reduction in stomatal conductance in the highest concentrations of the metal. The excess of Fe in the cultivation solution increased its concentration in the seedlings biomass, with the roots being principally responsible for the bioaccumulation. Although R. mangle plants showed clear signs of stress to excess Fe, they also have a strong capacity for bioaccumulation and tolerance.
... However, despite the reduction in these parameters, there was no significant variation in Ci (vpm). According to Alves et al. (2011), a lower A should not only be associated with the lower entry of CO 2 in the leaves, but with some biochemical limitation in the fixation of CO 2 within the chloroplasts. The increase in A μmol m -2 s -1 and the invariability of Ci were similar to data obtained from seedlings in mangrove areas affected by the tailings plume from the Fundão dam (RRDM, 2020). ...
