ABSTRACT
Groundnut is an important global food and oil crop that underpins agriculture-dependent livelihood strategies meeting food, nutrition, and income security. Aflatoxins, pose a major challenge to increased competitiveness of groundnut limiting access to lucrative markets and affecting populations that consume it. Other drivers of low competitiveness include allergens and limited shelf life occasioned by low oleic acid profile in the oil. Thus grain off-takers such as consumers, domestic, and export markets as well as processors need solutions to increase profitability of the grain. There are some technological solutions to these challenges and this review paper highlights advances in crop improvement to enhance groundnut grain quality and nutrient profile for food, nutrition, and economic benefits. Significant advances have been made in setting the stage for marker-assisted allele pyramiding for different aflatoxin resistance mechanisms-in vitro seed colonization, pre-harvest aflatoxin contamination, and aflatoxin production-which, together with pre- and post-harvest management practices, will go a long way in mitigating the aflatoxin menace. A breakthrough in aflatoxin control is in sight with overexpression of antifungal plant defensins, and through host-induced gene silencing in the aflatoxin biosynthetic pathway. Similarly, genomic and biochemical approaches to allergen control are in good progress, with the identification of homologs of the allergen encoding genes and development of monoclonal antibody based ELISA protocol to screen for and quantify major allergens. Double mutation of the allotetraploid homeologous genes, FAD2A and FAD2B, has shown potential for achieving >75% oleic acid as demonstrated among introgression lines. Significant advances have been made in seed systems research to bridge the gap between trait discovery, deployment, and delivery through innovative partnerships and action learning.
ABSTRACT
This study was aimed at isolation and characterization of natural antifungal compounds for grain mold, a key parasitic fungal disease of sorghum. Pseudomonas fluorescens strain isolated from rhizosphere of groundnut crop was selected as a source. Its biocontrolling ability was assessed by testing some biochemical attributes such as phosphate-solubilization, and HCN, NH3 , indole-3-acetic acid, and siderophore production. The strain showed positive result for all except indole-3-acetic acid, revealing its suitability for a further study. The antibiotic-sensitivity pattern of the strain against 43 antibiotics was also established, which showed resistance to 15 antibiotics. The efficacy of P. fluorescens strain against grain mold was identified by dual culture technique. Hundred percent inhibition was found against Fusarium moniliforme, an important causative agent of this disease. The strain was fermented for secondary metabolites and extracted with AcOEt. Chromatographic separation of the extract yielded four known compounds, cyclo(L-Pro-L-Phe) (1), cyclo(trans-4-hydroxy-L-Pro-L-Leu) (2), cyclo(trans-4-hydroxy-L-Pro-L-Phe) (3), and cyclo(Gly-L-Pro) (4), which were characterized by spectral analysis and optical rotation. The crude extract, a mixture of 2 and 3, and isolated 1 were proved to be significantly effective against grain mold fungi. This is the first report on production of these cyclic dipeptides by P. fluorescens and their antagonistic properties.
