Phospholipids profile in chloroplasts of Coffea spp. genotypes differing in cold acclimation ability

Elemental composition, total fatty acids, soluble sugar content and essential oils of flowers and leaves of Moringa oleifera cultivated in Southern Portugal

The evaluation of the elemental content of moringa leaves and flowers by Energy Dispersive X-Ray Fluorescence Spectrometry revealed that the leaves are a good source of some macro (Ca and K) and micronutrients (Mn) beyond the presence of important polyunsaturated fatty acids (PUFAs), essential in human nutrition. Total soluble sugars prevail in the flowers which may be linked to insect attraction and the pollination process. M. oleifera leaves, flowers and seeds essential oils (EOs) were isolated by hydrodistillation. Gas chromatography and gas chromatography-mass spectrometry analysis (GC-MS) showed EOs dominated by alkanes and fatty acids in diverse ratios in the analyzed plant parts. The nutritional characterization of M. oleifera cultivated in Portugal showed some important nutrients to human physiology. Further studies will allow determining if its consumption may overcome the nutritional imbalances of daily modern households, preventing the emergence of hypertension and diabetes.

Metabolomic Analysis, Combined with Enzymatic and Transcriptome Assays, to Reveal the Browning Resistance Mechanism of Fresh-Cut Eggplant

Browning has been the primary limitation in eggplant processing. This study investigates the molecular mechanism underlying fresh-cut eggplant fruit browning by observing the physicochemical characteristics of browning-resistant (‘F’) and browning-sensitive (‘36′) eggplant cultivars. Browning-related enzyme activity and gene expression (PPO, LOX, and PLD) were significantly higher in the ‘36′ eggplant, thereby enhancing the degree of browning, compared to the ‘F’ eggplant. The MDA content and O₂⁻ production rate progressively increased as browning increased, while the antioxidant capacity of the fruit decreased. The cutting injury significantly activated the expression of PAL, thereby inducing the accumulation of phenolic acids, while the PPO gene was significantly upregulated, which activated the activity of polyphenol oxidase. Our results showed that the oxidation of chlorogenic acids to chlorogenic quinones resulted in the occurrence of browning, which suggests chlorogenic acid as the main browning substrate in fresh-cut eggplant.

Correlations between allocation to foliar phosphorus fractions and maintenance of photosynthetic integrity in six mangrove populations as affected by chilling

Chilling restrains the distribution of mangroves. We tested whether foliar phosphorus (P) fractions and gene expression are associated with cold tolerance in mangrove species. We exposed seedlings of six mangrove populations from different latitudes to favorable, chilling and recovery treatments, and measured their foliar P concentrations and fractions, photochemistry, nighttime respiration, and gene expression. A Kandelia obovata (KO; 26.45°N) population completely and a Bruguiera gymnorhiza (Guangxi) (BGG; 21.50°N) population partially (30%) survived chilling. Avicennia marina (24.29°N), and other B. gymnorhiza (26.66°N, 24.40°N, and 19.62°N) populations died after chilling. Photosystems of KO and photosystem I of BGG were least injured. During chilling, leaf P fractions, except nucleic acid P in three populations, declined and photoinhibition and nighttime respiration increased in all populations, with the greatest impact in B. gymnorhiza. Leaf nucleic acid P was positively correlated with photochemical efficiency during recovery and nighttime respiration across populations for each treatment. Relatively high concentrations of nucleic acid P and metabolite P were associated with stronger chilling tolerance in KO. Bruguiera gymnorhiza exhibited relatively low concentrations of organic P in favorable and chilling conditions, but its partially survived population showed stronger compensation in nucleic acid P and Pi concentrations and gene expression during recovery.

Primary Metabolite Profile Changes in Coffea spp. Promoted by Single and Combined Exposure to Drought and Elevated CO2 Concentration

Climate change scenarios pose major threats to many crops worldwide, including coffee. We explored the primary metabolite responses in two Coffea genotypes, C. canephora cv. Conilon Clone 153 and C. arabica cv. Icatu, grown at normal (aCO₂) or elevated (eCO₂) CO₂ concentrations of 380 or 700 ppm, respectively, under well-watered (WW), moderate (MWD), or severe (SWD) water deficit conditions, in order to assess coffee responses to drought and how eCO₂ can influence such responses. Primary metabolites were analyzed with a gas chromatography time-of-flight mass spectrometry metabolomics platform (GC-TOF-MS). A total of 48 primary metabolites were identified in both genotypes (23 amino acids and derivatives, 10 organic acids, 11 sugars, and 4 other metabolites), with differences recorded in both genotypes. Increased metabolite levels were observed in CL153 plants under single and combined conditions of aCO₂ and drought (MWD and SWD), as opposed to the observed decreased levels under eCO₂ in both drought conditions. In contrast, Icatu showed minor differences under MWD, and increased levels (especially amino acids) only under SWD at both CO₂ concentration conditions, although with a tendency towards greater increases under eCO₂. Altogether, CL153 demonstrated large impact under MWD, and seemed not to benefit from eCO₂ in either MWD and SWD, in contrast with Icatu.

Metabolomics and Transcriptomics Analyses of Two Contrasting Cherry Rootstocks in Response to Drought Stress

Drought is one of the main factors affecting sweet cherry yields, and cherry rootstocks can provide a range of tree vigor levels to better match sweet cherries with the characteristics of the soil. To investigate the molecular events of the cherry to water deficiency, we performed transcriptomic and metabolomic analyses of Prunus mahaleb CDR-1 (drought-tolerant cherry rootstock (DT)) and P. cerasus × P. canescens Gisela 5 (drought-susceptible cherry rootstock (DS)), respectively. The results revealed 253 common drought-responsive genes in leaves and roots in DT and 17 in DS; 59 upregulated metabolites were explored in leaves in DT and 19 were explored in DS. Differentially expressed metabolites related to the cyanoamino acid metabolism pathway and phenylpropanoid biosynthesis pathway may be key factors in the difference in drought resistance in the two rootstocks. Moreover, six central metabolites-3-cyanoalanine, phenylalanine, quinic acid, asparagine, p-benzoquinone, and phytosphingosine-were identified as potential biological markers of drought response in cherries and may be key factors in the difference in drought resistance, along with caffeic acid and chlorogenic acid. We also selected 17 differentially expressed genes as core candidate genes and the mechanism of DT in response to drought is summarized.

The β-ketoacyl-CoA synthase KCS13 regulates the cold response in cotton by modulating lipid and oxylipin biosynthesis

Cold stress is a key environmental factor that affects plant development and productivity. In this study, RNA-seq in cotton following cold-stress treatment resulted in the identification of 5239 differentially expressed genes (DEGs) between two cultivars with differing sensitivity to low temperatures, among which GhKCS13 was found to be involved in the response. Transgenic plants overexpressing GhKCS13 showed increased sensitivity to cold stress. KEGG analysis of 418 DEGs in both GhKCS13-overexpressing and RNAi lines after treatment at 4 °C indicated that lipid biosynthesis and linoleic acid metabolism were related to cold stress. ESI-MS/MS analysis showed that overexpression of GhKCS13 led to modifications in the composition of sphingolipids and glycerolipids in the leaves, which might alter the fluidity of the cell membrane under cold conditions. In particular, differences in levels of jasmonic acid (JA) in GhKCS13 transgenic lines suggested that, together with lysophospholipids, it might mediate the cold-stress response. Our results suggest that overexpression of GhKCS13 probably causes remodeling of lipids in the endoplasmic reticulum and biosynthesis of lipid-derived JA in chloroplasts, which might account for the increased sensitivity to cold stress in the transgenic plants. Complex interactions between lipid components, lipid signaling molecules, and JA appear to determine the response to cold stress in cotton.

Very-long-chain fatty acids (VLCFAs) in plant response to stress

Plant growth is affected by various stresses leading to changes in metabolism. Stress conditions include a variety of biotic and abiotic factors such as pathogens, drought, high and low temperatures and heavy metals. Among multiple physiological responses to stress, there is an adaptive modification in membrane lipid constituents. In particular, the composition of membrane very-long-chain fatty acids (VLCFAs) changes both qualitatively and quantitatively. Here, we evaluate the current data on the effects of stress on plant VLCFAs composition. In summary, some stress conditions lead to an increase of the total amount of saturated and, in certain cases, unsaturated VLCFAs. Currently, it is not completely clear how these molecules participate in the biology of plant cell membranes. Their possible functional roles are discussed.

TAG pathway engineering via GPAT2 concurrently potentiates abiotic stress tolerance and oleaginicity in Phaeodactylum tricornutum

BACKGROUND

Despite the great potential of marine diatoms in biofuel sector, commercially viable biofuel production from native diatom strain is impractical. Targeted engineering of TAG pathway represents a promising approach; however, recruitment of potential candidate has been regarded as critical. Here, we identified a glycerol-3-phosphate acyltransferase 2 (GPAT2) isoform and overexpressed in Phaeodactylum tricornutum.

RESULTS

GPAT2 overexpression did not impair growth and photosynthesis. GPAT2 overexpression reduced carbohydrates and protein content, however, lipid content were significantly increased. Specifically, TAG content was notably increased by 2.9-fold than phospho- and glyco-lipids. GPAT2 overexpression elicited the push-and-pull strategy by increasing the abundance of substrates for the subsequent metabolic enzymes, thereby increased the expression of LPAAT and DGAT. Besides, GPAT2-mediated lipid overproduction coordinated the expression of NADPH biosynthetic genes. GPAT2 altered the fatty acid profile in TAGs with C16:0 as the predominant fatty acid moieties. We further investigated the impact of GPAT2 on conferring abiotic stress, which exhibited enhanced tolerance to hyposaline (70%) and chilling (10 ºC) conditions via altered fatty acid saturation level.

CONCLUSIONS

Collectively, our results exemplified the critical role of GPAT2 in hyperaccumulating TAGs with altered fatty acid profile, which in turn uphold resistance to abiotic stress conditions.

Climate change does not impact on Coffea arabica yield in Brazil

BACKGROUND

Brazil is the largest producer of coffee in the world. Studies on climate change estimate large impacts on the production of Coffea arabica (C. arabica). In this context, it is necessary to know the quantitative production values to provide evidence for policy makers to target the prompt answer.

RESULTS

Using data from 18 municipalities located in five Brazilian states that produce more coffee in Brazil, in an unprecedented way, in this work it is shown that although the minimum temperature is the most important climatic variable for the production, its effect, although positive, and its degree of explanation, were technically too small to explain the volume of production in Brazilian conditions. According to the model of non-stationary time series ARIMA (1, 1, 0) coffee production in the future may reach almost four million tons, and the productivity almost 2500 kg ha^-1 on average, with the advancement of technology as the main factor that should promote simultaneous increases in production and productivity. However, despite natural climate variations, which make it the most responsible for the variability of annual coffee production, the producer must increase the use of the technologies to support the Brazilian coffee agribusiness.

CONCLUSIONS

The results of this study reveal that coffee production in Brazil is due much more to productivity than to the minimum ambient temperature change over the long term; despite this, the climate variable should be considered the most influential on the production and productivity of coffee. © 2017 Embrapa. Journal of the Science of Food and Agriculture © 2019 Society of Chemical Industry.

Stress cross-response of the antioxidative system promoted by superimposed drought and cold conditions in Coffea spp

The understanding of acclimation strategies to low temperature and water availability is decisive to ensure coffee crop sustainability, since these environmental conditions determine the suitability of cultivation areas. In this context, the impacts of single and combined exposure to drought and cold were evaluated in three genotypes of the two major cropped species, Coffea arabica cv. Icatu, Coffea canephora cv. Apoatã, and the hybrid Obatã. Crucial traits of plant resilience to environmental stresses have been examined: photosynthesis, lipoperoxidation and the antioxidant response. Drought and/or cold promoted leaf dehydration, which was accompanied by stomatal and mesophyll limitations that impaired leaf C-assimilation in all genotypes. However, Icatu showed a lower impact upon stress exposure and a faster and complete photosynthetic recovery. Although lipoperoxidation was increased by drought (Icatu) and cold (all genotypes), it was greatly reduced by stress interaction, especially in Icatu. In fact, although the antioxidative system was reinforced under single drought and cold exposure (e.g., activity of enzymes as Cu,Zn-superoxide dismutase, ascorbate peroxidase, APX, glutathione reductase and catalase, CAT), the stronger increases were observed upon the simultaneous exposure to both stresses, which was accompanied with a transcriptional response of some genes, namely related to APX. Complementary, non-enzyme antioxidant molecules were promoted mostly by cold and the stress interaction, including α-tocopherol (in C. arabica plants), ascorbate (ASC), zeaxanthin, and phenolic compounds (all genotypes). In general, drought promoted antioxidant enzymes activity, whereas cold enhanced the synthesis of both enzyme and non-enzyme antioxidants, the latter likely related to a higher need of antioxidative capability when enzyme reactions were probably quite repressed by low temperature. Icatu showed the wider antioxidative capability, with the triggering of all studied antioxidative molecules by drought (except CAT), cold, and, particularly, stress interaction (except ASC), revealing a clear stress cross-tolerance. This justified the lower impacts on membrane lipoperoxidation and photosynthetic capacity under stress interaction conditions, related to a better ROS control. These findings are also relevant to coffee water management, showing that watering in the cold season should be largely avoided.

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO₂] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO₂] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO₂] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO₂ L^-1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30-35 or 36-40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p-coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality), and only marginally, if at all, by elevated [CO₂]. However, the [CO₂] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids), thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p-coumaric acids, trigonelline, chroma, Hue angle, and color index), and increasing desirable features (acidity). Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO₂] (e.g., phosphorous) and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO₂] contributed to preserve bean quality by modifying and mitigating the heat impact on physical and chemical traits of coffee beans, which is clearly relevant in a context of predicted climate change and global warming scenarios.

Antioxidative ability and membrane integrity in salt-induced responses of Casuarina glauca Sieber ex Spreng. in symbiosis with N2-fixing Frankia Thr or supplemented with mineral nitrogen

The actinorhizal tree Casuarina glauca tolerates extreme environmental conditions, such as high salinity. This species is also able to establish a root-nodule symbiosis with N2-fixing bacteria of the genus Frankia. Recent studies have shown that C. glauca tolerance to high salt concentrations is innate and linked to photosynthetic adjustments. In this study we have examined the impact of increasing NaCl concentrations (200, 400 and 600mM) on membrane integrity as well as on the control of oxidative stress in branchlets of symbiotic (NOD+) and non-symbiotic (KNO3+) C. glauca. Membrane selectivity was maintained in both plant groups at 200mM NaCl, accompanied by an increase in the activity of antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, glutathione reductase and catalase). Regarding cellular membrane lipid composition, linolenic acid (C18:3) showed a significant decline at 200mM NaCl in both NOD+ and KNO3+ plants. In addition, total fatty acids (TFA) and C18:2 also decreased in NOD+ plants at this salt concentration, resulting in malondialdehyde (MDA) production. Such initial impact at 200mM NaCl is probably due to the fact that NOD+ plants are subjected to a double stress, i.e., salinity and low nitrogen availability. At 400mM NaCl a strong reduction of TFA and C18:3 levels was observed in both plant groups. This was accompanied by a decrease in the unsaturation degree of membrane lipids in NOD+. However, in both NOD+ and KNO3+ lipid modifications were not reflected by membrane leakage at 200 or 400mM, suggesting acclimation mechanisms at the membrane level. The fact that membrane selectivity was impaired only at 600mM NaCl in both groups of plants points to a high tolerance of C. glauca to salt stress independently of the symbiotic relation with Frankia.

The Greater Phenotypic Homeostasis of the Allopolyploid Coffea arabica Improved the Transcriptional Homeostasis Over that of Both Diploid Parents

Polyploidy impacts the diversity of plant species, giving rise to novel phenotypes and leading to ecological diversification. In order to observe adaptive and evolutionary capacities of polyploids, we compared the growth, primary metabolism and transcriptomic expression level in the leaves of the newly formed allotetraploid Coffea arabica species compared with its two diploid parental species (Coffea eugenioides and Coffea canephora), exposed to four thermal regimes (TRs; 18-14, 23-19, 28-24 and 33-29°C). The growth rate of the allopolyploid C. arabica was similar to that of C. canephora under the hottest TR and that of C. eugenioides under the coldest TR. For metabolite contents measured at the hottest TR, the allopolyploid showed similar behavior to C. canephora, the parent which tolerates higher growth temperatures in the natural environment. However, at the coldest TR, the allopolyploid displayed higher sucrose, raffinose and ABA contents than those of its two parents and similar linolenic acid leaf composition and Chl content to those of C. eugenioides. At the gene expression level, few differences between the allopolyploid and its parents were observed for studied genes linked to photosynthesis, respiration and the circadian clock, whereas genes linked to redox activity showed a greater capacity of the allopolyploid for homeostasis. Finally, we found that the overall transcriptional response to TRs of the allopolyploid was more homeostatic compared with its parents. This better transcriptional homeostasis of the allopolyploid C. arabica afforded a greater phenotypic homeostasis when faced with environments that are unsuited to the diploid parental species.

The plasma membrane transport systems and adaptation to salinity

Salt stress represents one of the environmental challenges that drastically affect plant growth and yield. Evidence suggests that glycophytes and halophytes have a salt tolerance mechanisms working at the cellular level, and the plasma membrane (PM) is believed to be one facet of the cellular mechanisms. The responses of the PM transport proteins to salinity in contrasting species/cultivars were discussed. The review provides a comprehensive overview of the recent advances describing the crucial roles that the PM transport systems have in plant adaptation to salt. Several lines of evidence were presented to demonstrate the correlation between the PM transport proteins and adaptation of plants to high salinity. How alterations in these transport systems of the PM allow plants to cope with the salt stress was also addressed. Although inconsistencies exist in some of the information related to the responses of the PM transport proteins to salinity in different species/cultivars, their key roles in adaptation of plants to high salinity is obvious and evident, and cannot be precluded. Despite the promising results, detailed investigations at the cellular/molecular level are needed in some issues of the PM transport systems in response to salinity to further evaluate their implication in salt tolerance.

Sustained photosynthetic performance of Coffea spp. under long-term enhanced [CO2]

Coffee is one of the world's most traded agricultural products. Modeling studies have predicted that climate change will have a strong impact on the suitability of current cultivation areas, but these studies have not anticipated possible mitigating effects of the elevated atmospheric [CO2] because no information exists for the coffee plant. Potted plants from two genotypes of Coffea arabica and one of C. canephora were grown under controlled conditions of irradiance (800 μmol m(-2) s(-1)), RH (75%) and 380 or 700 μL CO2 L(-1) for 1 year, without water, nutrient or root development restrictions. In all genotypes, the high [CO2] treatment promoted opposite trends for stomatal density and size, which decreased and increased, respectively. Regardless of the genotype or the growth [CO2], the net rate of CO2 assimilation increased (34-49%) when measured at 700 than at 380 μL CO2 L(-1). This result, together with the almost unchanged stomatal conductance, led to an instantaneous water use efficiency increase. The results also showed a reinforcement of photosynthetic (and respiratory) components, namely thylakoid electron transport and the activities of RuBisCo, ribulose 5-phosphate kinase, malate dehydrogenase and pyruvate kinase, what may have contributed to the enhancements in the maximum rates of electron transport, carboxylation and photosynthetic capacity under elevated [CO2], although these responses were genotype dependent. The photosystem II efficiency, energy driven to photochemical events, non-structural carbohydrates, photosynthetic pigment and membrane permeability did not respond to [CO2] supply. Some alterations in total fatty acid content and the unsaturation level of the chloroplast membranes were noted but, apparently, did not affect photosynthetic functioning. Despite some differences among the genotypes, no clear species-dependent responses to elevated [CO2] were observed. Overall, as no apparent sign of photosynthetic down-regulation was found, our data suggest that Coffea spp. plants may successfully cope with high [CO2] under the present experimental conditions.