scholarly journals Phytochrome light receptors control metabolic flux, and their action during seedling development sets the trajectory for biomass production

2019 ◽  
Author(s):  
Johanna Krahmer ◽  
Ammad Abbas ◽  
Virginie Mengin ◽  
Hirofumi Ishihara ◽  
Thiago A Moraes ◽  
...  

AbstractThe phytochromes (phys) photoreceptors are known to be major regulators of plastic growth responses to vegetation shade. Recent reports have begun to uncover an important role for phys in carbon resource management. Our earlier work showed that phy mutants had a distinct metabolic profile with elevated levels of metabolites including TCA intermediates, amino acids and sugars. Here we show that in seedlings phy regulates the balance between glucose and starch. Multi-allele phy mutants have excess glucose and low starch levels, which is conducive to hypocotyl elongation. 13C-CO2 labelling demonstrates that metabolic flux balance in adult plants is markedly altered in phy mutants. Phytochrome reduces synthesis rates of stress metabolites, including raffinose and proline and several typical stress-induced biosynthetic genes related to these metabolites show higher expression in phy mutants.Since growth and metabolism are typically inter-connected, we investigated why phy mutants have severely reduced biomass. Quantification of carbon fixation, biomass accumulation, and 13C labelling of cell wall polysaccharides established that relative growth rate is impaired in multi allele phy mutants for the first 2.5 weeks after germination but equivalent to the WT thereafter. Mathematical modelling predicts that the altered growth dynamics and final biomass deficit can be explained by the smaller cotyledon size of the multiple phy mutants. This indicates that the established role of phy in promoting seedling establishment has enduring effects that govern adult plant biomass.

Author(s):  
Johanna Krahmer ◽  
Ammad Abbas ◽  
Virginie Mengin ◽  
Hirofumi Ishihara ◽  
Andrés Romanowski ◽  
...  

Abstract Phytochrome (phy) photoreceptors are known to regulate plastic growth responses to vegetation shade. However, recent reports also suggest an important role for phys in carbon resource management, metabolism, and growth. Here, we use 13CO2 labelling patterns in multi-allele phy mutants to investigate the role of phy in the control of metabolic fluxes. We also combine quantitative data of 13C incorporation into protein and cell wall polymers, gas exchange measurements and system modelling to investigate why biomass is decreased in adult multi-allele phy mutants. Phy influences the synthesis of stress metabolites like raffinose and proline, and the accumulation of sugars, possibly through regulating vacuolar sugar transport. Remarkably, despite their modified metabolism and vastly altered architecture, growth rates in adult phy mutants resemble those of wild-type plants. Our results point to delayed seedling growth and smaller cotyledon size as the cause of the adult-stage phy mutant biomass defect. Our data signify a role for phy in metabolic stress physiology, carbon partitioning and illustrate that phy action at the seedling stage sets the trajectory for adult biomass production.


Author(s):  
Sadat M. R. Khattab ◽  
Takashi Watanabe

Glycerol is an eco-friendly solvent that enhances plant biomass decomposition via glycerolysis in many pretreatment methods. Nonetheless, inefficient conversion of glycerol to ethanol by natural Saccharomyces cerevisiae limits its use in these processes. Here, we have developed an efficient glycerol-converting yeast strain by genetically modifying the oxidation of cytosolic nicotinamide adenine dinucleotide (NADH) by an O 2 -dependent dynamic shuttle and abolishing both glycerol phosphorylation and biosynthesis in S. cerevisiae D452-2 strain, as well as vigorous expression of whole genes in the DHA-pathway ( Candid utilis glycerol facilitator, Ogataea polymorpha glycerol dehydrogenase, endogenous dihydroxyacetone kinase, and triosephosphate isomerase). The engineered strain showed conversion efficiencies (CE) up to 0.49 g ethanol/g glycerol (98% of theoretical CE), with production rate >1 g/L −1 h −1 when glycerol was supplemented in a single fed-batch fermentation in a rich medium. Furthermore, the engineered strain converted a mixture of glycerol and glucose into bioethanol (>86 g/L) with 92.8% CE. To the best of our knowledge, this is the highest reported titer of bioethanol produced from glycerol and glucose. Notably, we developed a glycerol-utilizing transformant from parent strain, which cannot utilize glycerol as a sole carbon source. The developed strain converted glycerol to ethanol with a productivity of 0.44 g/L −1 h −1 on minimal medium under semi-aerobic conditions. Our findings will promote the utilization of glycerol in eco-friendly biorefineries and integrate bioethanol and plant-oil industries. IMPORTANCE With the development of efficient lignocellulosic biorefineries, glycerol has attracted attention as an eco-friendly biomass-derived solvent that can enhance the dissociation of lignin and cell wall polysaccharides during the pretreatment process. Co-conversion of glycerol with the sugars released from biomass after glycerolysis increases the resources for ethanol production and lowers the burden of component separation. However, low conversion efficiency from glycerol and sugars limits the industrial application of this process. Therefore, the generation of an efficient glycerol-fermenting yeast will promote the applicability of integrated biorefineries. Hence, metabolic flux control in yeast grown on glycerol will lead to the generation of cell factories that produce chemicals, which will boost biodiesel and bioethanol industries. Additionally, the use of glycerol-fermenting yeast will reduce global warming and generation of agricultural waste, leading to the establishment of a sustainable society.


2016 ◽  
Vol 113 (27) ◽  
pp. 7667-7672 ◽  
Author(s):  
Deyue Yang ◽  
Daniel D. Seaton ◽  
Johanna Krahmer ◽  
Karen J. Halliday

Plants sense the light environment through an ensemble of photoreceptors. Members of the phytochrome class of light receptors are known to play a critical role in seedling establishment, and are among the best-characterized plant signaling components. Phytochromes also regulate adult plant growth; however, our knowledge of this process is rather fragmented. This study demonstrates that phytochrome controls carbon allocation and biomass production in the developing plant. Phytochrome mutants have a reduced CO2 uptake, yet overaccumulate daytime sucrose and starch. This finding suggests that even though carbon fixation is impeded, the available carbon resources are not fully used for growth during the day. Supporting this notion, phytochrome depletion alters the proportion of day:night growth. In addition, phytochrome loss leads to sizeable reductions in overall growth, dry weight, total protein levels, and the expression of CELLULOSE SYNTHASE-LIKE genes. Because cellulose and protein are major constituents of plant biomass, our data point to an important role for phytochrome in regulating these fundamental components of plant productivity. We show that phytochrome loss impacts core metabolism, leading to elevated levels of tricarboxylic acid cycle intermediates, amino acids, sugar derivatives, and notably the stress metabolites proline and raffinose. Furthermore, the already growth-retarded phytochrome mutants are less responsive to growth-inhibiting abiotic stresses and have elevated expression of stress marker genes. This coordinated response appears to divert resources from energetically costly biomass production to improve resilience. In nature, this strategy may be activated in phytochrome-disabling, vegetation-dense habitats to enhance survival in potentially resource-limiting conditions.


2021 ◽  
Author(s):  
Sadat M. R. Khattab ◽  
Takashi Watanabe

ABSTRACTGlycerol is an eco-friendly solvent enhancing plant-biomass decomposition through a glycerolysis process in many pretreatment methods. Nonetheless, the lack of efficient conversion of glycerol by natural Saccharomyces cerevisiae restrains many of these scenarios. Here we outline the complete strategy for the generation of efficient glycerol fermenting yeast by rewriting the oxidation of cytosolic nicotinamide adenine dinucleotide (NADH) by O2-dependent dynamic shuttle while abolishing both glycerol phosphorylation and biosynthesis pathways. By following a vigorous glycerol oxidative pathway, the engineered strain demonstrated augmentation in conversion efficiency (CE) reach up to 0.49g-ethanol/g-glycerol—98% of theoretical conversion—with production rate >1 g/L-1h-1 when supplementing glycerol as a single fed-batch on a rich-medium. Furthermore, the engineered strain showed a new capability toward ferment a mixture of glycerol and glucose with producing >86 g/L of bioethanol with 92.8% of the CE. To our knowledge, this is the highest ever reported titer in this regard. Notably, this strategy flipped our ancestral yeast from non-growth on glycerol, on the minimal medium, to a fermenting strain with productivities 0.25-0.5 g/L-1h-1 and 84-78% of CE, respectively and 90% of total conversions to the products. The findings in metabolic engineering here may release the limitations of utilizing glycerol in several eco-friendly biorefinery approaches.IMPORTANCEWith the avenues for achieving efficient lignocellulosic biorefinery scenarios, glycerol gained keen attention as an eco-friendly biomass-derived solvent for enhancing the dissociation of lignin and cell wall polysaccharides during pretreatment process. Co-fermentation of glycerol with the released sugars from biomass after the glycerolysis expands the resource for ethanol production and release from the burden of component separation. Titer productivities are one of the main obstacles for industrial applications of this process. Therefore, the generation of highly efficient glycerol fermenting yeast significantly promotes the applicability of the integrated biorefineries scenario. Besides, the glycerol is an important carbon resource for producing chemicals. Hence, the metabolic flux control of yeast from glycerol contributes to generation of cell factory producing chemicals from glycerol, promoting the association between biodiesel and bioethanol industries. Thus, this study will shed light on solving the problems of global warming and agricultural wastes, leading to establishment of the sustainable society.


Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
J. Julio Camarero ◽  
Cristina Valeriano ◽  
Antonio Gazol ◽  
Michele Colangelo ◽  
Raúl Sánchez-Salguero

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions.


Agriculture ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 370
Author(s):  
Murugesan Chandrasekaran

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts of higher plants which increase the growth and nutrient uptake of host plants. The primary objective was initiated based on analyzing the enormity of optimal effects upon AMF inoculation in a comparative bias between mycorrhizal and non-mycorrhizal plants stipulated on plant biomass and nutrient uptake. Consequently, in accomplishing the above-mentioned objective a vast literature was collected, analyzed, and evaluated to establish a weighted meta-analysis irrespective of AMF species, plant species, family and functional group, and experimental conditions in the context of beneficial effects of AMF. I found a significant increase in the shoot, root, and total biomass by 36.3%, 28.5%, and, 29.7%, respectively. Moreover, mycorrhizal plants significantly increased phosphorus, nitrogen, and potassium uptake by 36.3%, 22.1%, and 18.5%, respectively. Affirmatively upon cross-verification studies, plant growth parameters intensification was accredited to AMF (Rhizophagus fasciculatus followed by Funniliforme mosseae), plants (Triticum aestivum followed by Solanum lycopersicum), and plant functional groups (dicot, herbs, and perennial) were the additional vital important significant predictor variables of plant growth responses. Therefore, the meta-analysis concluded that the emancipated prominent root characteristics, increased morphological traits that eventually help the host plants for efficient phosphorus uptake, thereby enhancing plant biomass. The present analysis can be rationalized for any plant stress and assessment of any microbial agent that contributes to plant growth promotion.


2016 ◽  
Vol 205 ◽  
pp. 59-69 ◽  
Author(s):  
Daniele Massa ◽  
Domenico Prisa ◽  
Enzo Montoneri ◽  
Daniele Battaglini ◽  
Marco Ginepro ◽  
...  

2021 ◽  
Vol 39 (2) ◽  
pp. 186-191
Author(s):  
Jhonatan M Goulart ◽  
Adriano A Rocha ◽  
José Antonio A Espindola ◽  
Ednaldo da S Araújo ◽  
José Guilherme M Guerra

ABSTRACT This study aimed to evaluate sweet potato performance in succession to annual herbaceous leguminous plants, in monocropping or intercropped with corn, under agroecological management, under Baixada Fluminense conditions. The experimental design was randomized blocks, with five treatments and four replicates. The treatments consisted of pre-cropping with the following species: crotalária (Crotalaria juncea) under monocropping system, crotalária intercropped with corn (Zea mays), jack bean (Canavalia ensiformis) under monocropping system, jack bean intercropped with corn and spontaneous vegetation. The results showed that monocropped crotalária reached the greatest dry biomass accumulation during two consecutive years of succession. In the second year, this treatment provided greater accumulated amounts of N, K and Mg in plant biomass. Growing sweet potatoes in succession to the pre-cropping of crotalária is advantageous, as it provided an increase in vegetable productivity in the second year of succession.


2011 ◽  
Vol 91 (2) ◽  
pp. 305-314 ◽  
Author(s):  
Cody Chytyk ◽  
Pierre Hucl ◽  
Gordon Gray

Chytyk, C. J., Hucl, P. J. and Gray, G. R. 2011. Leaf photosynthetic properties and biomass accumulation of selected western Canadian spring wheat cultivars. Can. J. Plant Sci. 91: 305–314. Current studies indicate wheat straw as a viable source for the production of cellulosic ethanol. Since photosynthetic performance impacts the overall success of the mature plant, this study aimed to measure the photosynthetic vigour of 11 spring wheat cultivars during field development as well as their biomass composition at maturity to determine which would be optimum for ethanol production. All cultivars had similar maximal quantum yields of photosystem II photochemistry (FV/FM), normalized difference vegetation index and biomass composition in the field. However, differences were observed in photosynthetic rate, with McKenzie having the highest light-saturated maximal rate of CO2 uptake (A max) and apparent quantum yield of CO2 uptake (Φapp CO2), while also having the best water use efficiency. Snowbird was found to have the lowest CO2-compensation point (Γ*) and A max. Upon subjecting wheat samples to photoinhibitory conditions, McKenzie and Kyle were found to be the most resistant and susceptible, respectively, with a difference of 11% in FV/FM. Abundance of xanthophyll pigments were not found to be a contributing cause to differential photoinhibitory resistance as there was not a noticeable difference between cultivars. Although some cultivars were found to have enhanced photosynthetic traits over others, these were slight and did not contribute to changes in plant biomass. However, McKenzie did present a higher cellulose content, which would be favourable for ethanol production.


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