Adenylate cyclases (ACs), much like guanylate cyclases (GCs), are increasingly recognized as essential parts of many plant processes including biotic and abiotic stress responses. In order to identify novel ACs, we have applied a search motif derived from experimentally tested GCs and identified a number of Arabidopsis thaliana candidates including a clathrin assembly protein (AT1G68110; AtClAP). AtClAP contains a catalytic centre that can complement the AC-deficient mutant cyaA in E. coli, and a recombinant AtClAP fragment (AtClAP261–379) can produce cyclic adenosine 3′,5′ monophosphate (cAMP) from adenosine triphosphate (ATP) in vitro. Furthermore, an integrated analysis of gene expression and expression correlation implicate cAMP in pathogen defense and in actin cytoskeletal remodeling during endocytic internalization.

Adenylate cyclases (ACs) are enzymes capable of converting adenosine-5'-triphosphate to cyclic 3', 5'--adenosine monophosphate (cAMP). In animals and lower eukaryotes, ACs and their product cAMP have firmly been established as important signalling molecules with important roles in several cellular signal transduction pathways. However, in higher plants, the only annotated and experimentally confirmed AC is a Zea mays pollen protein capable of generating cAMP. Recently a number of candidate AC-encoding genes in Arabidopsis thaliana have been proposed based on functionally assigned amino acids in the catalytic center of annotated and/or experimentally tested nucleotide cyclases in lower and higher eukaryotes. Here we detail the cloning and recombinant expression of functional candidate AC domains using, as an example, the A. thaliana pentatricopeptide repeat-containing protein (AtPPR-AC; At1g62590). Through a complementation test, in vivo adenylate cyclase activity of candidate recombinant molecules can be prescreened and promising candidates can subsequently be further evaluated in an in vitro AC immunoassay.

Most plants demonstrate wide interactive and complex adaptive morphological, biochemical, and physiological responses when subjected to salinity stress. Salt stress negatively impacts agricultural yields more especially cultivated crops throughout the world. Of interest to this study is maize a saltsensitive crop that is widely grown worldwide, and receiving most attention due to its significant attributes and ability to serve as a great model for stress response studies. We exposed QN701 maize cultivar, to simulated salinity stress and investigated its morphological and physiological responses. Salinity negatively induced various morphological responses such as the reduction in plant height, number of leaves, shoot and root (length and biomass), and leaf width; however, it significantly increased the leaf area. On the physiological aspect, salt stress decreased the number of stomata, stomatal density, and photosynthesis, while it increased the respiration rate. This study expanded our knowledge of the morphological and physiological responses of maize to salinity stress. Additionally, these findings may serve as a recommendation for salinity breeding programs in maize and related cereal crops.

No abstract

Soybean [Glycine max (L.) Merrill] is a high value leguminous crop characterized by its excellent protein content and ability to improve soil quality through nitrogen fixation. Whereas this plant has attractive human and animal feed attributes in addition to its pharmaceutical and industrial uses, its growth and yield are severely affected by drought. Thus any research aimed at understanding the genome response of this plant to drought and other related environmental stress factors would be worthwhile. In plants, in general, second messengers have a key role in linking and coordinating environmental stimuli to cellular communication and responses. One group of such messengers are adenylyl cyclases (ACs) and their catalytic product 3′,5′-cyclic adenosine monophosphate (cAMP), involved in plant growth, cell division, reproduction, development and response to stress. However, while ACs have been reported in some plant species such as Arabidopsis and maize, their presence together with their cAMP-dependent systems in G. max have largely remained unavailable. Fortunately, a putative molecule, Glyma.07G251000 (accession number: XP_003529590), with a predicted function as an AC in G. max has at some point been reported. This molecule harbors a domain annotated AC catalytic center and therefore, was herein targeted for study. In order to characterize the Glyma.07G251000, we cloned and expressed it, followed by purification of the resultant recombinant protein (GmAC). When tested in vitro for AC activity, the GmAC protein showed a Mn 2+ -dependent activity that is positively enhanced by calcium. GmAC also complemented the AC-deficiency (cyaA mutation) of an SP850 mutant strain when expressed in Escherichia coli. When analysed by a web-based approach system, the GmAC protein was found to be co-expressed and co-regulated with various other proteins responsible for early plant development and stress response, strongly suggesting that it has a central role in these two key cellular processes. In addition, the GmAC protein conferred stress resistance to EXPRESS BL21 (DE3) pLysS DUOs cells when expressed in these host cells under salt (200 mM NaCl) and oxidative stress (0.2 mM H2O2). Conceivably, our findings showed that GmAC is an AC protein with a role in early plant development and stress response. Highlighted Conclusions1. GmAC is an adenylyl cyclase and the first ever such protein to be identified in soybean. 2. GmAC confers stress tolerance to Escherichia coli and is co-expressed/co-regulated with other soybean proteins responsible for early plant development and stress response.

Introduction: Drought is the main abiotic stress responsible for crop loss worldwide. Maize (Zea mays L.) is a widely grown drought-sensitive crop used as a staple food by the growing population. Therefore, it is imperative to assess the molecular mechanisms behind drought response and tolerance in maize. Transcriptomic profiling of abiotic stress responsive pathways in various crops appeared to be an unreliable approach due to post-transcriptional modifications, while there is limited published data on molecular mechanisms of osmotic-stress response in maize. Hence our study aimed at profiling osmotic stress responsive proteins augmented by their associated morphological features in Z. mays. Materials and Methods: In this regard, morphological and proteomic investigations were carried out on 16-day maize seedlings exposed to 5% (w/v) and 10% (w/v) polyethylene glycol(PEG) to induce osmotic-stress. Proteomics approach (one-dimensional (1D) and two-dimensional (2D) gel electrophoresis) compared differential protein abundance between controls and the osmotic stressed maize plants. Results: Morphological parameters such as plant growth, height, shoot diameter, leaf area, and colour were highly affected with PEG treatment as compared to the untreated ones. Molecular evaluation by 1D gel electrophoresis revealed that the separated protein patterns were highly expressed in the experiments than the controls. Using 2D gel electrophoresis, a total of seven and eight protein spots were revealed in experimental plants under 5% (w/v) and 10% (w/v) PEG treatment respectively while the control plants only expressed one protein. Increased drought stress resulted in a greater number of proteins with differential abundance. Conclusion: This study has successfully profiled the total osmotic stress responsive proteins and revealed the efficiency of proteomic tools in the qualitative detection of differential proteins from maize.

Water stress affects plant growth and development, leading to agricultural crop losses in maize cultivation. It also threatens food security in economical crops such as maize, one of the major crops produced worldwide. Transcriptomic studies associated with morphological assessments have been widely conducted on the mechanisms of crop development and stress response; however, data on maize is still very much limited. Hence herein, we used both the morphological and proteomic analyses to investigate and establish physical features and proteins associated with maize in response to osmotic stress. In addition, proteomic analysis (1DE and 2DE techniques) was used to separate and enumerate water stress responsive proteins. Morphologically, a decrease in the overall growth of the maize plant as a result of water stress was observed, whereby features such as leaf colour and size, shoot height and stem diameter were negatively affected. Through proteomics analyses, a total of nine expressed proteins were revealed in response to water stress. Overall, this work, has successfully profiled the water stress responsive proteins and specifically indicating the efficiency of proteomic tools in the detection and analysis of qualitative proteins from maize.

The rapid expansion and reproduction of certain plant species represents one of the biggest problems in aquatic environments, ranging from eutrophication to the limited availability of water for human consumption. Among these plants is water hyacinth (Eichhornia crassipes), a herbaceous hydrophyte often branded the world's worst aquatic weed due to its invasive aggression, negative impact on aquatic environments, and the cost usually associated with its management. Water hyacinth is a biomass, typically rich in lignocellulosic material and making it a potential raw material for the synthesis of products of industrial and domestic interest; e.g. edible fungi. Among the commonly known edible fungi is Lentinus edodes, a commercial mushroom whose versatile nature as a white rot fungus provides basis for the continued exploration of its biochemical processes during solid state fermentation on various lignocellulosic biomass as potential substrates. The fungus naturally feeds on lignocellulose by secreting various extracellular enzymes responsible for breaking down this organic polymer into simple soluble molecules that the hyphae can absorb and develop into mycelia. In this study, L. edodes was assessed for its ability to grow on water hyacinth and possibly utilizing it as a substrate. When cultured onto this noxious biomass followed by assessment by agar plate-based clearing assay and spectrophotometry, the fungus demonstrated its ability to secrete cellulases, xylanases, pectinases, peroxidases and laccases, thus showing its capabilities to physiologically utilize this hydrophyte as a substrate. If properly optimized, this approach can be remarkably used as a sustainable way to control water hyacinth in Zimbabwe.