Conservation Agriculture Affects Grain and Nutrient Yields of Maize (Zea Mays L.) and Can Impact Food and Nutrition Security in Sub-Saharan Africa

TaLAC129 is a negative regulator of arbuscular mycorrhizal symbiosis but enhanced the growth and yield of bread wheat

Arbuscular mycorrhizal (AM) symbiosis enhances nutrient acquisition and stress resilience in plants, yet the genetic mechanisms regulating this interaction in wheat remain poorly understood. This study explores the variation in AM colonization rates across a diverse set of wheat varieties and aims to identify key genes that regulate the wheat-AM symbiosis. Understanding these molecular mechanisms is crucial for improving nutrient uptake efficiency and stress resistance in wheat breeding programs. Here, we conducted a genome-wide association study (GWAS) of 291 wheat varieties and integrated transcriptomic data to identify TaLAC129, a laccase (LAC)-encoding gene, as a critical negative regulator of AM colonization in wheat roots. Overexpression of TaLAC129 significantly increased root LAC activity and lignin content, concurrently suppressing AM colonization. While this suppression reduced nitrogen (N), phosphorus (P), and potassium (K) uptake in stems, leaves, and glumes, it markedly enhanced nutrient utilization efficiency (NUE) in grains. Furthermore, TaLAC129 overexpression improved agronomic traits, including grains per panicle, 1000-grain weight, and overall yield. Our findings reveal the dual role of TaLAC129 in balancing AM symbiosis and nutrient allocation, offering a novel genetic target for breeding wheat varieties with improved yield and nutrient efficiency. This study provides critical insights into the molecular coordination between symbiotic trade-offs and agricultural productivity in cereal crops.

Exposure to Aflatoxins and Ochratoxin A From the Consumption of Selected Staples and Fresh Cow Milk in the Wet and Dry Seasons in Ghana

Across sub-Saharan Africa, the heavy reliance on mycotoxin-susceptible staple foods means that populations in the region are particularly vulnerable to chronic mycotoxin exposure. This study assessed the exposure risk to ochratoxin A (OTA) and aflatoxins (AFs) from 18 samples of selected staple foods (maize, millet, groundnut) and 56 fresh cow milk samples collected from across Ghana. The foods were sampled simultaneously to maximise comparability, and at two timepoints in March/April (during the dry season) and July/August (during the rainy season) to assess the effects of duration of storage and seasonal conditions on the mycotoxin levels as measured by high-performance liquid chromatography. The margin of exposure (MOE) approach was used to assess the exposure risk from consumption of the sampled foods. Each of the sampled staples was contaminated with OTA (0.19-3.11 ng/g) and at least one AF (0.75-13.05 ng/g B1, ND-12.12 ng/g B2, 0.1-9.95 ng/g G1, ND-16.78 ng/g G2). Up to 67% had contamination above European Food Safety Authority (EFSA) maximum limits, and 50% were above Ghana Standards Authority (GSA) limits. The fresh cow milk samples were contaminated with AFM1 in the range of 0.05-1.49 ng/g, with 95% above EFSA limits and 36% above GSA limits. Aflatoxin contamination in the staples was high, particularly in July/August when the wet conditions may have adversely impacted the handling and storage of farm produce. Variation in AFM1 between the two sampling periods mirrored total aflatoxin in the staples, suggesting that even if dairy cattle were grazing in open pasture and not being rationed on stored feed, then there was a high environmental presence of aflatoxigenic fungi. The MOE estimates were ≤ 533.09, far below the safe cut-off of 10,000 for suspected carcinogenic compounds. The high mycotoxin levels indicate a priority risk to child nutrition which relies heavily on cereal mixes based on one or all the three sampled staples. The data from this study underscore the urgent need for interventions to better appreciate and address mycotoxin exposure for enhanced food security and public health in Ghana and across sub-Saharan Africa.

Selenium Status of Southern Africa

Selenium is an essential trace element that exists in inorganic forms (selenite and selenates) and organic forms (selenoamino acids, seleno peptides, and selenoproteins). Selenium is known to aid in the function of the immune system for populations where human immunodeficiency virus (HIV) is endemic, as studies suggest that a lack of selenium is associated with a higher risk of mortality among those with HIV. In a recent study conducted in Zambia, adults had a median plasma selenium concentration of 0.27 μmol/L (IQR 0.14-0.43). Concentrations consistent with deficiency (<0.63 μmol/L) were found in 83% of adults. With these results, it can be clearly seen that selenium levels in Southern Africa should be investigated to ensure the good health of both livestock and humans. The recommended selenium dietary requirement of most domesticated livestock is 0.3 mg Se/kg, and in humans above 19 years, anRDA (recommended daily allowance) of 55 mcg Se/per dayisis recommended, but most of the research findings of Southern African countries have recorded low levels. With research findings showing alarming low levels of selenium in soils, humans, and raw feed materials in Southern Africa, further research will be vital in answering questions on how best to improve the selenium status of Southern African soils and plants for livestock and humans to attain sufficient quantities.

The Impact of Permethrin and Cypermethrin on Plants, Soil Enzyme Activity, and Microbial Communities

Pyrethroids are insecticides most commonly used for insect control to boost agricultural production. The aim of the present research was to determine the effect of permethrin and cypermethrin on cultured and non-cultivated bacteria and fungi and on the activity of soil enzymes, as well as to determine the usefulness of Zea mays in mitigating the adverse effects of the tested pyrethroids on the soil microbiome. The analyses were carried out in the samples of both soil not sown with any plant and soil sown with Zea mays. Permethrin and cypermethrin were found to stimulate the multiplication of cultured organotrophic bacteria (on average by 38.3%) and actinomycetes (on average by 80.2%), and to inhibit fungi growth (on average by 31.7%) and the enzymatic activity of the soil, reducing the soil biochemical fertility index (BA) by 27.7%. They also modified the number of operational taxonomic units (OTUs) of the Actinobacteria and Proteobacteria phyla and the Ascomycota and Basidiomycota phyla. The pressure of permethrin and cypermethrin was tolerated well by the bacteria Sphingomonas (clone 3214512, 1052559, 237613, 1048605) and Bacillus (clone New.ReferenceOTU111, 593219, 578257), and by the fungi Penicillium (SH1533734.08FU, SH1692798.08FU) and Trichocladium (SH1615601.08FU). Both insecticides disturbed the growth and yielding of Zea mays, as a result of which its yield and leaf greenness index decreased. The cultivation of Zea mays had a positive effect on both soil enzymes and soil microorganisms and mitigated the anomalies caused by the tested insecticides in the microbiome and activity of soil enzymes. Permethrin decreased the yield of its aerial parts by 37.9% and its roots by 33.9%, whereas respective decreases caused by cypermethrin reached 16.8% and 4.3%.