TSHEGOFATSO DIKOBE

Agriculture is an essential sector for the increasing world population, hence the need for more food production.  However, the aim of increasing food crop production is mostly suppressed by abiotic stresses such as drought and salinity. Salinity is a major limiting factor that inhibits the potential of plant growth and productivity worldwide. Hence, understanding the mechanisms behind plant stress response is important for developing new biomarker approaches that will increase salt tolerance in crops.  To survive, plants exhibit various morphological, physiological, and biochemical processes when faced with saline conditions. This study was carried out to explore and evaluate the morphological and physiological effects of salinity on maize grown in the absence/presence of NaCl, followed by measurement of the various growth parameters at the end of a treatment cycle.  Results of the study revealed that salt stress significantly decreased growth parameters such as plant height, leaf n...

Background Second messengers have a key role in linking environmental stimuli to cellular responses. One such messenger, 3′,5′-cyclic adenosine monophosphate (cAMP) generated by adenylyl cyclase (AC), has long been established as an essential signaling molecule in many physiological processes of higher plants, including growth, development and stress response. To date, very few ACs have been identified in plants, thus a need to search for more. Objective To test the probable AC activity of an Arabidopsis MEE (AtMEE) protein and infer its function bioinformatically. Methods A truncated version of the AtMEE protein (encoded by At2g34780 gene) harboring the annotated AC catalytic center (AtMEE-AC) was cloned and expressed in BL21 Star pLysS Escherichia coli cells followed by its purification using the nickel-nitriloacetic acid (Ni-NTA) affinity system. The purified protein was tested for its probable in vitro AC activity by enzyme immunoassay. The AtMEE-AC protein was also expressed in...

Most countries including South Africa, process surface water from lakes, rivers, dams and ponds by filtration, chlorination, alum treatment before use for drinking purposes. In South Africa, the North West Province in particular, residents of most rural communities do not have access to treated water. This exposes them to contamination with pathogens such as Escherichia coli. The aim of the study was, therefore, to isolate, identify and characterize E. coli strains from water collected from Setumo Dam, located at the Modimola village, in the periphery of the Mmabatho suburban area using conventional microbiological methods and PCR analysis. Water samples were collected during the summer season from three different sites of the dam, viz; upstream, middle stream and the downstream of the dam. Tap water was used as a control during analysis. Bacterial loads were determined by spread plating on mFC and EMBA and incubating the plates aerobically at 45oC and 37oC, respectively for 24 hour...

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 posttranscriptional 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.

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 ofcandidates including a clathrin assembly protein (AT1G68110; AtClAP). AtClAP contains a catalytic centre that can complement the AC-deficient mutantA in, and a recombinant AtClAP fragment (AtClAP) 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.