Process optimization for simultaneous production of phenolic acids and enzymes with high transfructosylation activity in cupuassu (Theobroma grandiflorum) residue by submerged fermentation with Aspergillus carbonarius

Cupuassu (Theobroma grandiflorum) generates a large amount of waste, which can be better used to obtain products with high added value through biotechnological processes. Thus, the present study aimed to obtain optimized conditions for the simultaneous production of phenolic acids, invertases and transferases enzymes in cupuassu residue with Aspergillus carbonarius. The main methodologies used to select the variables that influence the system were a Plackett-Burman design, followed by a Central Composite Rotational Design. The optimal conditions were use of 17.3% sucrose, 5.1% residue and 4.6% yeast extract to produce 2204.89 ± 5.75 mg GAE/100 g, 39.84 ± 2.08 U/mL of hydrolytic activity, 168.09 ± 3.81 U/mL of transfructosylation activity and 4.23 ± 0.19 of transfructosylation and hydrolytic activity ratio. Among the phenolic acids identified by the UFLC-DAD system, there was an increase of 148.17% in gallic acid and 205.51% in protocatechuic acid. The antioxidant activities also showed changes after fermentation, with an increase of 350% for the ABTS assay, 51.97% for FRAP, 22.65% for ORAC and 16.03% for DPPH. To the best of our knowledge, this is the first time that cupuassu residue is fermented with Aspergillus carbonarius to obtain invertases and transferases enzymes and phenolic acids.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05418-z.

Elevated carbon dioxide offers promise for wheat adaptation to heat stress by adjusting carbohydrate metabolism

Carbohydrate metabolism in plants is influenced by thermodynamics. The amount of carbon dioxide (CO₂) in the atmosphere is expected to rise in the future. As a result, understanding the effects of higher CO₂ on carbohydrate metabolism and heat stress tolerance is necessary for anticipating plant responses to global warming and elevated CO₂. In this study, five wheat cultivars were exposed to heat stress (40 °C) at the onset of anthesis for three continuous days. These cultivars were grown at two levels of CO₂ i.e. ambient CO₂ level (a[CO₂], 380 mmol L^-1) and elevated CO₂ level (e[CO₂], 780 mmol L^-1), to determine the interactive effect of elevated CO₂ and heat stress on carbohydrate metabolism and antioxidant enzyme activity in wheat. Heat stress reduced the photosynthetic rate (Pn) and grain yield in all five cultivars, but cultivars grown in e[CO₂] sustained Pn and grain yield in contrast to cultivars grown in a[CO₂]. Heat stress reduced the activity of ADP-glucose pyrophosphorylase, UDP-glucose pyrophosphorylase, invertases, Glutathione reductase (GR), Peroxidase (POX), and Superoxide dismutase (SOD) at a[CO₂] but increased at e[CO₂]. The concentration of sucrose, glucose, and fructose mainly increased in tolerant cultivars under heat stress at e[CO₂]. This study confirms the interaction between the heat stress and e[CO2] to mitigate the effect of heat stress on wheat and suggests to have in-depth knowledge and precise understanding of carbohydrate metabolism in heat stressed plants in order to prevent the negative effects of high temperatures on productivity and other physiological attributes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-01080-5.

Serendipita indica changes host sugar and defense status in Arabidopsis thaliana: cooperation or exploitation?

Manipulation of sugar metabolism upon S. indica root colonization triggers changes in sugar pools and defense responses in A. thaliana. Serendipita indica is an endophytic fungus that establishes mutualistic relationships with many different plants including important crops as well as the model plant A. thaliana. Successful root colonization typically results in growth promotion and enhanced tolerance against various biotic and abiotic stresses. The fungus delivers phosphorus to the host and receives in exchange carbohydrates. There are hints that S. indica prefers hexoses, glucose, and fructose, products of saccharose cleavage driven by invertases (INVs) and sucrose synthases (SUSs). Carbohydrate metabolism in this interaction, however, remains still widely unexplored. Therefore, in this work, the sugar pools as well as the expression of SUSs and cytosolic INVs in plants colonized by S. indica were analyzed. Using sus1/2/3/4 and cinv1/2 mutants the importance of these genes for the induction of growth promotion and proper root colonization was demonstrated. Furthermore, the expression of several defense-related marker genes in both multiple mutants in comparison to the wild-type plants was determined. Our results show that in colonized A. thaliana plants S. indica manipulates the sugar metabolism by altering the expression of host's INV and SUS and modulates both the sugar pools and plant defense in its favor. We conclude that the interaction A. thaliana-S. indica is a balancing act between cooperation and exploitation, in which sugar metabolism plays a crucial role. Small changes in this mechanism can lead to severe disruption resulting in the lack of growth promotion or altered colonization rate.

Developmental patterns of enzyme activity, gene expression, and sugar content in sucrose metabolism of two broomrape species

A better understanding of broomrape physiological features opens up new perspectives for developing specific management strategies. For this purpose, activities of key enzymes involved in osmoregulation (SAI1, CWI, M6PR, and SUS1) were considered at developmental stages of two important broomrape species (Egyptian and branched broomrape) on tomato. While Egyptian broomrape tubercles had high activities of invertases, branched broomrape shoots revealed high activities of M6PR and SUS1 during both pre- and post-emergence stages except for M6PR at post-emergence stages of P. aegyptiaca. Interestingly, the main accumulation of total reducing sugars was detected in tubercle during pre- and in shoot during post-emergence. Unlike low levels of genes expression (except for CWI) before parasite emergence, significantly higher expression levels of SAI1, SUS1 and M6PR were detected after parasite emergence. Matching the expression levels of SAI1 and SUS1 genes with their corresponding enzymes activities makes them as the suitable candidates for gene silencing strategies.

EMF radiations (1800 MHz)-inhibited early seedling growth of maize (Zea mays) involves alterations in starch and sucrose metabolism

The present study investigated the impact of 1800-MHz electromagnetic field radiations (EMF-r), widely used in mobile communication, on the growth and activity of starch-, sucrose-, and phosphate-hydrolyzing enzymes in Zea mays seedlings. We exposed Z. mays to modulated continuous wave homogenous EMF-r at specific absorption rate (SAR) of 1.69±0.0 × 10(-1) W kg(-1) for ½, 1, 2, and 4 h. The analysis of seedlings after 7 days revealed that short-term exposure did not induce any significant change, while longer exposure of 4 h caused significant growth and biochemical alterations. There was a reduction in the root and coleoptile length with more pronounced effect on coleoptile growth (23 % reduction on 4-h exposure). The contents of photosynthetic pigments and total carbohydrates declined by 13 and 18 %, respectively, in 4-h exposure treatments compared to unexposed control. The activity of starch-hydrolyzing enzymes-α- and β-amylases-increased by ∼92 and 94 %, respectively, at an exposure duration of 4 h, over that in the control. In response to 4-h exposure treatment, the activity of sucrolytic enzymes-acid invertases and alkaline invertases-was increased by 88 and 266 %, whereas the specific activities of phosphohydrolytic enzymes (acid phosphatases and alkaline phosphatases) showed initial increase up to ≤2 h duration and then declined at >2 h exposure duration. The study concludes that EMF-r-inhibited seedling growth of Z. mays involves interference with starch and sucrose metabolism.

Spatial distribution and dynamics of sucrose metabolising enzymes in radiation induced mutants of sugarcane

Sucrose metabolism in various source and sink organs of developing sugarcane (Saccharum officinarum L.) plant is accompanied with continuous synthesis and cleavage. In this regard, the involvement of four major enzymes viz. sucrose synthase (SS), sucrose phosphate synthase (SPS), soluble acid (SAI) and neutral invertases (NI) is considered crucial. In this study, we have analysed in vivo enzymatic activity of 12th month old field grown radiation-induced sugarcane mutants identified for sucrose accumulation. The mutants showed significant differences in the spatial enzymatic regulation in leaves, immature and mature internodes; SPS and SS activities were found highest in high sucrose accumulating mutants (AKTS-02 and AKTS-20) along with lower levels of SAI activity. Overall positive correlation of SPS, SS and negative correlation of SAI, NI activities with sucrose content of the respective tissue types was observed. The SPS activity was found strongly associated with sucrose content in leaves (r(2) = 0.558) and internodes (r(2) = 0.514), whereas, the SAI activity was found significant in leaves (r(2) = 0.379) and weakly associated in internodal tissues (r(2) = 0.248). However, the associations were found to be non-significant for SS and NI activities in both leaves and internodes. Despite this, the differences in the SPS and SAI activities (SPS-SAI) in leaves (r(2) = 0.828) and internodal tissues (r(2) = 0.619) had shown greater influence on net sucrose synthesis and accumulation. To summarize, our results suggest differential sugar metabolism in the induced mutants and that such contrasting mutant germplasm with a relatively uniform genetic makeup can be useful in molecular studies on sucrose accumulation.

Hormonal and metabolic regulation of source-sink relations under salinity and drought: from plant survival to crop yield stability

Securing food production for the growing population will require closing the gap between potential crop productivity under optimal conditions and the yield captured by farmers under a changing environment, which is termed agronomical stability. Drought and salinity are major environmental factors contributing to the yield gap ultimately by inducing premature senescence in the photosynthetic source tissues of the plant and by reducing the number and growth of the harvestable sink organs by affecting the transport and use of assimilates between and within them. However, the changes in source-sink relations induced by stress also include adaptive changes in the reallocation of photoassimilates that influence crop productivity, ranging from plant survival to yield stability. While the massive utilization of -omic technologies in model plants is discovering hundreds of genes with potential impacts in alleviating short-term applied drought and salinity stress (usually measured as plant survival), only in relatively few cases has an effect on crop yield stability been proven. However, achieving the former does not necessarily imply the latter. Plant survival only requires water status conservation and delayed leaf senescence (thus maintaining source activity) that is usually accompanied by growth inhibition. However, yield stability will additionally require the maintenance or increase in sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves and to delayed stress-induced leaf senescence. This review emphasizes the role of several metabolic and hormonal factors influencing not only the source strength, but especially the sink activity and their inter-relations, and their potential to improve yield stability under drought and salinity stresses.