Isolation, identification and in silico analysis of alpha-amylase gene of Aspergillus niger strain CSA35 obtained from cassava undergoing spoilage

In this investigation, a gene (CDF_Amyl) encoding extracellular α-amylase in Aspergillus niger strain CSA35 associated with cassava spoilage was amplified using specific primers and characterized in silico. The gene had a partial nucleotide sequence of 968 bp and encoded a protein of 222 aa residues with a molecular weight and isoelectric point of 25.13 kDa and 4.17, respectively. Its catalytic site was located in the active site domain. BLASTp analysis showed that the protein primary sequence of the α-amylase gene had 98% and 99% homologies with the α-amylase of A. niger and A. oryzae RIB40, respectively. The gene is more closely related to α-amylase genes from fungi than to bacterial, plant, or animal α-amylase genes. Restriction mapping of the gene showed it can be digested with restriction enzymes like NcoI, PstI, SmaI, and BcLI among others but not with EcoRI and EcoRV. Its protein product had a hydrophobicity score of − 0.43 but no transmembrane helix. The CDF_Amyl protein was subcellularly localized in the secretory pathway, an indication of its release into extracellular space after secretion. Also, the 3D structure of the CDF-Amyl protein was barrel-shaped with domains characteristic of α-amylases. The encoded α-amylase Vmax is 6.90 U/mg protein and Km is 6.70 mg/ml. It was concluded that the unique characteristics of the CDF_Amyl gene and its deduced protein could find applications in biotechnological, food and pharmaceutical industries where cloning and further modification of this gene would be required for product development and improvement

Contrasting Response Mechanisms of Maize Lines to Striga hermonthica

Strigahermonthica (Del.) Benth is a parasitic weed that devastates cereals in Sub-Saharan Africa. Several control measures have been proposed for the parasite, of these, host plant resistance is considered the most cost-effective for poor farmers. Some tolerant/resistant lines have been developed and these lines display tolerance/resistance mechanisms to the parasite. A series of studies was done to investigate some of the mechanisms through which a resistant (TZISTR1108) and a susceptible (5057) maize line responds to S. hermonthica infestation, as well as the effects of parasitism on these lines. In this study, TZISTR1108 stimulated the germination and attachment of fewer S. hermonthica plants than 5057, both in the laboratory and on the field. In TZISTR1108, the growth of the S. hermonthica plants, that successfully attached, was slowed. When compared to the un-infested plants, the infested resistant plants showed fewer effects of parasitism than the infested susceptible plants. The infested TZISTR1108 plants were more vigorous, taller and resembled their un-infected counterparts. There were substantial reductions in the stomatal conductance and nitrogen content of the 5057 upon infestation. The resistant inbred line showed multiple mechanisms of resistance to S. hermonthica infestation. It thrives better than the susceptible line by reducing the attachment of S. hermonthica and it delays the parasite’s development