New insights into the origin and evolution of α-amylase genes in green plants

PpMYB10.1 regulates peach fruit starch degradation by activating PpBAM2

Starch degradation, a crucial source for soluble sugar, significantly influences fruit flavor development during ripening. Key enzymes in this process include α-amylases (AMYs) and β-amylases (BAMs). In this study, we identified 5 PpAMYs and 9 PpBAMs in peach and categorized them into three and four groups, respectively, based on the gene structures and the phylogenetic analysis. Subsequent expression analysis revealed that elevated levels of PpAMY1, PpAMY5, and PpBAM2 were detected in the middle and late stages of fruit development, suggesting their positive involvement in starch degradation during peach fruit ripening. Transient overexpression experiments conducted in peach fruits and callus further demonstrated that overexpression of PpBAM2 significantly reduced starch content, indicating its important role in starch degradation during peach fruit ripening. Furthermore, we identified a R2R3-MYB transcription factor, PpMYB10.1, which activated the expression of PpBAM2 through the direct interacting with its promoter. In addition, transient overexpression of PpMYB10.1 could significantly reduce starch content in peach callus. Consequently, our findings highlight the positive role of PpBAM2 in peach starch degradation, with PpMYB10.1 serving as an activator during this process.

PpAmy1 Plays a Role in Fruit-Cracking by Regulating Mesocarp Starch Hydrolysis of Nectarines

Nectarine [Prunus persica (L.) Batsch var.] fruits are highly susceptible to cracking during the ripening process, which significantly decreases their commercial value. In this study, we investigated the underlying mechanism of nectarine fruit-cracking using two nectarine varieties, namely, "Qiannianhong" (cracking-susceptible) and "CR1012" (cracking-resistant). Our findings indicate that nectarine fruit-cracking occurs during the second stage of fruit expansion. Despite no differences in epicarp cell size between "Qiannianhong" and "CR1012", the mesocarp cells of "Qiannianhong" were larger than those of "CR1012". Moreover, a comparison of starch hydrolysis between the two varieties revealed that "CR1012" had higher starch content in the mesocarp but lower soluble sugar content compared to "Qiannianhong". Additionally, by testing the α-amylase and β-amylase activity of the mesocarp, our results showed a difference only in α-amylase activity between the two varieties. Furthermore, qRT-PCR detection indicated a higher expression level of the PpAmy1 (α-amylase synthesis gene) in "Qiannianhong" compared to "CR1012". To further investigate the role of PpAmy1, we employed RNAi technology to suppress its expression in "Qiannianhong" fruits. The results showed a significant reduction in α-amylase activity, starch hydrolysis, soluble sugar content, cell size of the mesocarp, and fruit-cracking. These findings underscore the pivotal role of PpAmy1 in the occurrence of nectarine fruit cracking.

Traits variation of acorns and cupules during maturation process in Quercus variabilis and Quercus aliena

Quercus variabilis and Quercus aliena are two native tree species in China, which have similar habitats, and their regeneration mainly depends on acorn dispersal. This study analyzed the contents of water, soluble sugar, starch, soluble protein, and total phenolics in acorns and cupules during the whole development process to explore the difference between species. Thereinto, starch and total phenol occupied the dominant roles as their high contents. The acorn starch contents increased sharply during development in both species, but the contents in Q. variabilis were almost twice those of Q. aliena when mature. Similarly, high expression levels of starch synthase, soluble starch synthase 2 (SSS2) were also found in the acorns of Q. variabilis. The total phenol contents in Q. variabilis acorns were high at the early stages, and decreased sharply to similar contents in Q. aliena when mature. Additionally, the cupules in Q. variabilis had high contents of total phenols during the whole development period. Similar trends were also found in the expression patterns of UGT84A13 and SDH. The high total phenols in acorns and cupules of Q. variabilis probably protect the acorns from Mechoris ursulus, as only Q. aliena suffered a severe pest infestation in the early development stages. This study not only clarifies the interspecific difference between storage and defense substances during the development process in acorns and cupules, but also deepens understanding the specialized mechanisms of plant-pest/animal interactions in Quercus.

Potential Roles of α-amylase in Alzheimer's Disease: Biomarker and Drug Target

Alzheimer's disease (AD), the most common form of dementia, is pathologically characterized by the deposition of amyloid-β plaques and the formation of neurofibrillary tangles. In a neurodegenerative brain, glucose metabolism is also impaired and considered as one of the key features in AD patients. The impairment causes a reduction in glucose transporters and the uptake of glucose as well as alterations in the specific activity of glycolytic enzymes. Recently, it has been reported that α-amylase, a polysaccharide-degrading enzyme, is present in the human brain. The enzyme is known to be associated with various diseases such as type 2 diabetes mellitus and hyperamylasaemia. With this information at hand, we hypothesize that α-amylase could have a vital role in the demented brains of AD patients. This review aims to shed insight into the possible link between the expression levels of α-amylase and AD. Lastly, we also cover the diverse role of amylase inhibitors and how they could serve as a therapeutic agent to manage or stop AD progression.

Magneto-priming promotes nitric oxide via nitric oxide synthase to ameliorate the UV-B stress during germination of soybean seedlings

We have evaluated the contribution of nitric oxide (NO) in static magnetic field (SMF-200 mT for 1h) induced tolerance towards UV-B stress in soybean seedlings using various NO modulators like sodium nitroprusside (SNP), inhibitor of nitrate reductase (NR) sodium tungstate (ST), NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) and diphenylene iodonium (DPI) a NADPH oxidase inhibitor. The UV-B exposure significantly reduced germination, seedling growth together with activities of total amylase, NOS and NR in seedlings from un-primed seeds whereas SMF-primed seedlings showed significant enhancement in all these parameters along with higher level of NO/ROS. The supply of NO donor, SNP further improved all the seedlings parameters in un-primed and SMF-primed seeds after UV-B exposure. While ST, L-NAME and DPI significantly reduced the SMF-induced seedling performance after UV-B exposure. The gene expression study also showed significant up-regulation of α-amylase (GmAMY1, GmAMY2), nitric oxide synthase (GmNOS2) and nitrate reductase (GmNR2) encoding genes in UV-B exposed SMF-primed seedlings over un-primed seedlings. In particular, SNP+UV-B treatment enhanced the GmNOS2 expression in both unprimed (31.9-fold) and SMF-primed (93.2-fold) seedlings in comparison to their respective controls of CK+UV-B. In contrast, L-NAME+UV-B treatment reduced the SMF-induced GmNOS2 expression (4.8-fold) and NOS activity (76%). It confirmed that NO may be the key signaling molecule in SMF stimulated tolerance towards UV-B stress during early seedling growth and NOS may possibly be accountable for SMF-triggered NO production in soybean seedlings exposed to UV-B irradiations.

Escherichia coli expression and characterization of α-amylase from Geobacillus thermodenitrificans DSM-465

Alpha amylase, catalyzing the hydrolysis of starch is a ubiquitous enzyme with tremendous industrial applications. A 1698 bp gene coding for 565 amino acid amylase was PCR amplified from Geobacillus thermodenitrificans DSM-465, cloned in pET21a (+) plasmid, expressed in BL21 (DE3) strain of E. coli and characterized. The recombinant enzyme exhibited molecular weight of 63 kDa, optimum pH 8, optimum temperature 70°C, and KM value of 157.7µM. On pilot scale, the purified enzyme efficiently removed up to 95% starch from the cotton fabric indicating its desizing ability at high temperature. 3D model of enzyme built by Raptor-X and validated by Ramachandran plot appeared as a monomer having 31% α-helices, 15% β-sheets, and 52% loops. Docking studies have shown the best binding affinity of enzyme with amylopectin (∆G -10.59). According to our results, Asp 232, Glu274, Arg448, Glu385, Asp34, Asn276, and Arg175 constitute the potential active site of enzyme.

Adaptive innovation of green plants by horizontal gene transfer

Horizontal gene transfer (HGT) refers to the movement of genetic material between distinct species by means other than sexual reproduction. HGT has contributed tremendously to the genome plasticity and adaptive evolution of prokaryotes and certain unicellular eukaryotes. The evolution of green plants from chlorophyte algae to angiosperms and from water to land represents a process of adaptation to diverse environments, which has been facilitated by acquisition of genetic material from other organisms. In this article, we review the occurrence of HGT in major lineages of green plants, including chlorophyte and charophyte green algae, bryophytes, lycophytes, ferns, and seed plants. In addition, we discuss the significance of horizontally acquired genes in the adaptive innovations of green plants and their potential applications to crop breeding and improvement.

The tale of a versatile enzyme: Alpha-amylase evolution, structure, and potential biotechnological applications for the bioremediation of n-alkanes

As the primary source of a wide range of industrial products, the study of petroleum-derived compounds is of pivotal importance. However, the process of oil extraction and refinement is among the most environmentally hazardous practices, impacting almost all levels of the ecological chain. So far, the most appropriate strategy to overcome such an issue is through bioremediation, which revolves around the employment of different microorganisms to degrade hazardous compounds, generating less environmental impact and lower monetary costs. In this sense, a myriad of organisms and enzymes are considered possible candidates for the bioremediation process. Amidst the potential candidates is α-amylase, an evolutionary conserved starch-degrading enzyme. Notably, α-amylase was not only seen to degrade n-alkanes, a subclass of alkanes considered the most abundant petroleum-derived compounds but also low-density polyethylene, a dangerous pollutant produced from petroleum. Thus, due to its high conservation in both eukaryotic and prokaryotic lineages, in addition to the capability to degrade different types of hazardous compounds, the study of α-amylase becomes a rising interest. Nevertheless, there are no studies that review all biotechnological applications of α-amylase for bioremediation. In this work, we critically review the potential biotechnological applications of α-amylase, focusing on the biodegradation of petroleum-derived compounds. Evolutionary aspects are discussed, as well for all structural information and all features that could impact on the employment of this protein in the biotechnological industry, such as pH, temperature, and medium conditions. New perspectives and critical assessments are conducted regarding the application of α-amylase in the bioremediation of n-alkanes.

From reproduction to production, stomata are the master regulators

The best predictor of leaf level photosynthetic rate is the porosity of the leaf surface, as determined by the number and aperture of stomata on the leaf. This remarkable correlation between stomatal porosity (or diffusive conductance to water vapour g_s ) and CO₂ assimilation rate (A) applies to all major lineages of vascular plants (Figure 1) and is sufficiently predictable that it provides the basis for the model most widely used to predict water and CO₂ fluxes from leaves and canopies. Yet the Ball-Berry formulation is only a phenomenological approximation that captures the emergent character of stomatal behaviour. Progressing to a more mechanistic prediction of plant gas exchange is challenging because of the diversity of biological components regulating stomatal action. These processes are the product of more than 400 million years of co-evolution between stomatal, vascular and photosynthetic tissues. Both molecular and structural components link the abiotic world of the whole plant with the turgor pressure of the epidermis and guard cells, which ultimately determine stomatal pore size and porosity to water and CO₂ exchange (New Phytol., 168, 2005, 275). In this review we seek to simplify stomatal behaviour by using an evolutionary perspective to understand the principal selective pressures involved in stomatal evolution, thus identifying the primary regulators of stomatal aperture. We start by considering the adaptive process that has locked together the regulation of water and carbon fluxes in vascular plants, finally examining specific evidence for evolution in the proteins responsible for regulating guard cell turgor.