Limitations to Photosynthesis in Leaves of Wheat Plants Infected by Pyricularia oryzae

Blast, caused by Pyricularia oryzae, has become an economically important disease in wheat in Brazil, but little effort has been devoted to understanding the wheat–P. oryzae interaction. This study was intended to determine the effects of P. oryzae infection on the photosynthetic process in wheat plants using a susceptible (BR 18) and a partially resistant cultivar (BRS 229). It was found that the net carbon assimilation rate (A), stomatal conductance (gs), and transpiration rate were dramatically reduced in both cultivars due to P. oryzae infection but to a lesser degree in BRS 229. Photosynthesis was impaired in asymptomatic leaf tissues, indicating that blast severity is not an acceptable indicator for predicting P. oryzae-induced reductions in A. The proportionally larger decreases in A than in gs, in parallel with increases in internal CO2 concentration (Ci), suggest that the lower influx of CO2 into the diseased leaves caused by stomatal closure was not a prominent factor associated with the reduction in A. Additional support for this conclusion comes from the nonsignificant correlation between A and gs, the negative correlation between A and Ci and the positive correlation between blast severity and Ci. Both the maximum rate of carboxylation and the maximum rate of electron transport were dramatically depressed at advanced stages of P. oryzae infection, mainly in BR 18, although the reduction in A was not closely related to the decrease in the electron transport rate. In conclusion, biochemical limitations likely related to the reduced activity of Rubisco, rather than diffusive limitations, were the main factor associated with decreases in A during the infection process of P. oryzae on wheat leaves.

Download Full-text

Expression of the ToxA and PtrPf2 genes of the phytopathogenic fungus Pyrenophora tritici-repentis at the beginning of the infection process

Ecological genetics ◽

10.17816/ecogen16362 ◽

2019 ◽

Author(s):

Nina V. Mironenko ◽

Alexandra S. Orina ◽

Nadezhda M. Kovalenko

Keyword(s):

Transcription Factor ◽

Wheat Variety ◽

Infection Process ◽

Phytopathogenic Fungus ◽

In Planta ◽

Effector Gene ◽

Pyrenophora Tritici Repentis ◽

Wheat Leaves ◽

Necrotrophic Effector

This study shows that the necrotrophic effector gene ToxA is differentially expressed in isolates of P. tritici-repentis fungus at different time periods after inoculation of the wheat variety Glenlea which has the gene Tsn1 controlling sensitivity to the necrosis inducing toxin Ptr ToxA. Two P. tritici-repentis isolates with different ability to cause necrosis on the leaves of Glenlea variety (nec + and nec-) and with different expression level of ToxA and gene of factor transcription PtrPf2 in vitro were used for analysis. Isolates of P. tritici-repentis are characterized by the differential expression of ToxA in planta. The expression of the ToxA gene in P. tritici-repentis ToxA+ isolates significantly increased when infected the wheat leaves compared to ToxA expression results obtained in vitro. The levels of ToxA expression in both isolates differed significantly after 24, 48 and 96 hours after inoculation, however, the dynamics of the trait change over time were similar. However, the highest ToxA expression in the virulent (nec+) isolate in contrast with the avirulent (nec-) isolate was observed at a point of 48 hours. Whereas the expression of regulating transcription factor PtrPf2 in planta differed imperceptibly from expression in vitro throughout the observation period. Obviously, the role of the fungal transcription factor in regulating the effector gene expression weakens in planta, and other mechanisms regulating the expression of pathogen genes at the biotrophic stage of the disease develop.

Download Full-text

Infection process of Pyricularia oryzae on the leaves of wheat seedlings

Tropical Plant Pathology ◽

10.1007/s40858-016-0068-6 ◽

2016 ◽

Vol 41 (2) ◽

pp. 123-127 ◽

Cited By ~ 6

Author(s):

Maria Fernanda Antunes Cruz ◽

Jonas Alberto Rios ◽

Leonardo Araujo ◽

Fabrício Ávila Rodrigues

Keyword(s):

Infection Process ◽

Pyricularia Oryzae ◽

Wheat Seedlings

Download Full-text

Homeostatic response of Aptian gymnosperms to changes in atmospheric CO2 concentrations

Geology ◽

10.1130/g48037.1 ◽

2021 ◽

Author(s):

Germán Mora ◽

Ana M. Carmo ◽

William Elliott

Keyword(s):

Stomatal Closure ◽

Carbon Assimilation ◽

Atmospheric Co2 ◽

The Past ◽

A Value ◽

Co2 Concentrations ◽

Bulk Organic Matter ◽

The Subject ◽

Atmospheric Co2 Concentrations ◽

Homeostatic Response

The sensitivity of plant carbon isotope fractionation (13Δleaf) to changes in atmospheric CO2 concentrations (Ca) is the subject of heavy debate, with some studies finding no sensitivity, while others show a strong dependency. We tested the hypothesis of photosynthetic homeostasis by using δ13C of n-alkanes, cuticles, and bulk organic matter of gymnosperm-rich rocks (Arundel Clay) from two sites deposited during the Aptian, a time that experienced significant Ca variations. Our results show no effect of Ca on 13Δleaf, and a relatively constant Ci/Ca (0.64 ± 0.04, 1σ; i—intercellular space), a value that is similar to that of modern gymnosperms. These results suggest that Aptian gymnosperms used homeostatic adjustments with rising Ca, probably involving increased carbon assimilation and/or stomatal closure, a response also found in modern gymnosperms. The similarity between Aptian and modern gymnosperms suggests that the processes responsible for regulating CO2 and water vapor exchange during photosynthesis have remained unaltered in gymnosperms for the past 128 m.y.

Download Full-text

The risk of wheat blast in rice-wheat-co-planting regions in China: MoO strains of Pyricularia oryzae cause typical symptom and host reaction on both wheat leaves and spikes

Phytopathology ◽

10.1094/phyto-10-20-0470-r ◽

2021 ◽

Author(s):

Shizhen Wang ◽

Jiaoyu Wang ◽

Zhen Zhang ◽

Zhongna Hao ◽

Xueming Zhu ◽

...

Keyword(s):

Global Warming ◽

Pyricularia Oryzae ◽

Wheat Cultivars ◽

Host Reaction ◽

Typical Symptom ◽

Wheat Blast ◽

Resistant Genes ◽

Wheat Leaves ◽

Cultivar Specificity ◽

Heading Stage

Triticum pathotype (MoT) of Magnaporthe oryzae (syn. Pyricularia oryzae) causes wheat blast, which has recently spread to Asia. To assess the potential risk of wheat blast in rice-wheat growing regions, we investigated the pathogenicity of 14 isolates of P. oryzae on 32 wheat cultivars, among which MoO isolates were completely avirulent on the wheat cultivars at 22℃, but caused various infection degrees at 25℃. These reactions at 25℃ were isolate- and cultivar- dependent like race-cultivar specificity which was also recognized at the heading stage and caused typical blast symptoms on spikes. Microscopic analyses indicated that a compatible MoO isolates produced appressoria and infection hyphae on wheat as on rice. By comparing transcriptomes in wheat-MoO interactions, a bulk of pathogen-related genes was up-/down- regulated in compatible and incompatible patterns, but that changes of gene transcription were more significant in compatible pattern. These results indicate that the temperature could influence the infection ratio of wheat with MoO, and some MoO strains could be potential pathogens that increase the risk for the outbreak of wheat blast in wheat-rice growing regions with global warming. In addition, certain wheat cultivars exhibited resistance and are assumed to carry promoting resistant genes to the MoO strains.

Download Full-text

Picolinic acid spray stimulates the antioxidative metabolism and minimizes impairments on photosynthesis on wheat leaves infected by Pyricularia oryzae

Physiologia Plantarum ◽

10.1111/ppl.12917 ◽

2019 ◽

Vol 167 (4) ◽

pp. 628-644 ◽

Cited By ~ 5

Author(s):

Carlos Eduardo Aucique‐Pérez ◽

Renata Sousa Resende ◽

Lara Beatriz Cruz Neto ◽

Fernanda Dornelas ◽

Fábio Murilo DaMatta ◽

...

Keyword(s):

Picolinic Acid ◽

Pyricularia Oryzae ◽

Antioxidative Metabolism ◽

Wheat Leaves

Download Full-text

Primary leaf‐type ferredoxin 1 participates in photosynthetic electron transport and carbon assimilation in rice

The Plant Journal ◽

10.1111/tpj.14904 ◽

2020 ◽

Vol 104 (1) ◽

pp. 44-58

Author(s):

Lei He ◽

Man Li ◽

Zhennan Qiu ◽

Dongdong Chen ◽

Guangheng Zhang ◽

...

Keyword(s):

Electron Transport ◽

Carbon Assimilation ◽

Photosynthetic Electron Transport ◽

Primary Leaf ◽

Leaf Type

Download Full-text

Physiological responses of natural plankton communities to ultraviolet-B radiation in Redberry Lake (Saskatchewan, Canada)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f96-322 ◽

1997 ◽

Vol 54 (3) ◽

pp. 705-714 ◽

Cited By ~ 6

Author(s):

G A Ferreyra ◽

S Demers ◽

P A del Giorgio ◽

J -P Chanut

Keyword(s):

Electron Transport ◽

Ultraviolet Radiation ◽

Chlorophyll A ◽

Transport System ◽

Carbon Assimilation ◽

Cell Number ◽

Ultraviolet B ◽

Electron Transport System ◽

Experimental Conditions ◽

Anthropogenic Modifications

Damaging effects of ultraviolet radiation on the aquatic biota, related to anthropogenic modifications in the ozone layer, have been extensively described. However, most of the research has focused on marine environments, and information about the effects of ultraviolet radiation on saline prairie lakes of Canada is lacking. To test the deleterious effects of ultraviolet-B (UV-B) radiation on the planktonic community, two exposure experiments were performed in Redberry Lake, Saskatchewan. The responses of primary productivity, phytoplankton chlorophyll a and size, bacterial changes, and the electron transport system to natural UV-B fluxes reaching the surface of the lake were studied. No clear effects of UV-B on phytoplankton carbon assimilation and chlorophyll a were observed. However, significant responses were found for the two phytoplankton size fractions studied (0.7-2 and >2 µm), which were more related to the experimental conditions than to UV-B effects. Bacteria presented a clear decrease in cell number under the highest UV-B doses, whereas the opposite was observed for the electron transport system activity.

Download Full-text

Corrigendum - Effects of a water stress on the photosynthesis and respiration of wheat ears

Australian Journal of Agricultural Research ◽

10.1071/ar9800857c ◽

1980 ◽

Vol 31 (5) ◽

pp. 857

Author(s):

B Marshall ◽

RH Sedgley ◽

PV Biscoe

Keyword(s):

Carbon Dioxide ◽

Water Stress ◽

Maximum Rate ◽

Dark Respiration ◽

Light Response ◽

Grain Filling ◽

Response Curves ◽

Rectangular Hyperbola ◽

Wheat Leaves ◽

Days After Anthesis

An experiment was conducted on Huntsman winter wheat to investigate the effects of a water stress applied at anthesis on the carbon dioxide exchange of the ears during grain filling. The water stress was created by excluding rain from the soil, not the foliage, of plants growing in the field. Control plants were well watered throughout the period when the treatment was imposed. At intervals for 32 days after anthesis, detailed measurements were made of the photosynthetic rate of ears at different irradiances and rates of ear dark respiration. The measurements were analysed by using the photosynthesis-light response model developed by Marshall and Biscoe (1980) for wheat leaves with a modification for the pathway of respiration from the grains to the glumes. The model is a non-rectangular hyperbola and uses four parameters: Pn,max (maximum rate of net photosynthesis), Rd (rate of dark respiration), � (photochemical efficiency at low light), and F (ratio of physical to total resistance to diffusion of carbon dioxide). Analysis showed that in wheat ears during grain filling, photosynthesis can be treated as occurring predominantly in the glumes and respiration in the grains. The shape of the photosynthesis-light response curves for ears from both treatments were similar, but differed from those for wheat leaves because the maximum rates of photosynthesis were reached more gradually with increasing irradiance. However, the measured response curves were still better fitted by the model than a rectangular hyperbola which has often been used in the past. The water stress at anthesis decreased the maximum rate of ear photosynthesis by 0.8 g carbon dioxide m-2 h-1 throughout the grain-filling period. Initially, the rates of ear respiration were the same, but 32 days after anthesis the treatment had decreased ear respiration rate from 0.04 to 0.01 g carbon dioxide h-1/grain.

Download Full-text

Interspecific Variations in the Growth, Water Relations and Photosynthetic Responses of Switchgrass Genotypes to Salinity Targets Salt Exclusion for Maximising Bioenergy Production

Agriculture ◽

10.3390/agriculture9090205 ◽

2019 ◽

Vol 9 (9) ◽

pp. 205

Author(s):

Ángel Cordero ◽

Idoia Garmendia ◽

Bruce A. Osborne

Keyword(s):

Stomatal Closure ◽

Carbon Assimilation ◽

Bioenergy Crops ◽

Salt Glands ◽

High Productivity ◽

Bioenergy Production ◽

Salt Exclusion ◽

The Alamo ◽

Photosynthetic Responses ◽

High Yields

The expansion in the cultivation of bioenergy crops to saline lands is of importance for ensuring food security as long as high productivity is maintained. The potential of switchgrass to grow under saline conditions was examined in three genotypes from a early seedling growth to full maturity at 50, 100, 200 and 300 mM of sodium chloride (NaCl). The carbon assimilation rates were generally lower and correlated to stomatal closure in plants exposed to salinity in all the tested genotypes. Based on the results of ion concentrations in different parts of the plant, switchgrass genotypes differed in their responses to NaCl. The Alamo genotype excluded salt from the roots, whereas Trailblazer and Kanlow accumulated it in the root, stem and leaf tissues. The increased leaf salt concentration was accompanied by a higher proline concentration in the 200 and 300 mM NaCl treatments toward the end of the experiment. Overall, Alamo showed the highest yields at all salinity levels, indicating that excluding salt from the roots may result in a better performance in terms of biomass production. The accumulation of salt observed in Kanlow and Trailblazer resulted in lower yields, even when other mechanisms, such as the production of salt glands, were observed, especially in Kanlow. These results suggest that the Alamo genotype has the ability to maintain high yields under saline conditions and that this characteristic could be further exploited for maximizing bioenergy production under saline conditions.

Download Full-text