Biology subjects

Ortega-Beltran, A.

Publications and source records attributed to Ortega-Beltran, A..

2 recordsLinked to original sources

bioRxiv2026

Provitamin A maize inbred lines exhibit resistance to multiple foliar diseases under laboratory and field conditions

Maize (Zea mays) is a staple food for millions in sub-Saharan Africa (SSA), contributing to both caloric intake and essential micronutrients. Recent breeding efforts have focused on enhancing its nutritional value by increasing provitamin A (PVA) carotenoid content to address vitamin A deficiency (VAD), a common problem among children under 5 years, pregnant and lactating mothers across SSA. However, high rainfall, and both warm and humid conditions in various SSA regions result in devastating foliar diseases such as maize streak virus (MSV), northern corn leaf blight (NCLB), southern corn leaf blight (SCLB), southern corn rust, grey leaf spot (GLS), and Curvularia leaf spot (CLS). Breeding for resistance can aid in mitigating yield losses caused by those diseases. Rapid, efficient screening methods can allow for examining large germplasm collections. The current study evaluated 21 maize inbred lines with contrasting PVA content, along with two commercial inbred controls, for resistance to Exserohilum turcicum, Bipolaris maydis, and Curvularia lunata, causal agents of NCLB, SCLB, and CLS, respectively, using a detached leaf assay (DLA) and under natural field infestation. Significant variation was detected among the inbreds, seven were classified as resistant to certain diseases, ten as moderately resistant, and six as susceptible to all foliar diseases. Overall, high PVA inbred lines had less susceptibility to NCLB, SCLB, and CLS. The results suggest that PVA-enriched maize inbred lines possess improved resistance to multiple foliar diseases. The field assessments of disease severity validated the effectiveness of the DLA in distinguishing resistant from susceptible inbred lines, and resistance to other diseases in field conditions was detected in parallel. The results indicate that high PVA maize has the potential to simultaneously address VAD, mycotoxin contamination in SSA with improved resistance to multiple foliar diseases.

plant biology↗

bioRxiv2024

Morphological, pathological and phylogenetic analyses identify a diverse group of Colletotrichum spp. causing leaf, pod, and flower diseases on the orphan legume African yam bean

African yam bean (AYB; Sphenostylis stenocarpa Hochst. Ex A. Rich.) is an underutilized legume indigenous to Africa. The crop has great potential as it can enhance food security and its chemical composition offers nutritional and medicinal opportunities. However, the low grain yield caused by fungal diseases, including pod blight and leaf tip dieback, deters farmers from large-scale cultivation. The causal agents of pod and leaf tip dieback on AYB are largely uncharacterized. To determine the prevalence of fungal diseases affecting leaves, pods, and flowers of AYB, a survey was conducted in 2018 and 2019 in major AYB-growing areas in Nigeria. Leaf tip dieback, flower bud rot, and pod blight were the most common symptoms. Morphological and molecular assays were conducted to identify the causal agents of the observed diseases. In all the samples examined, fungi from eight genera were isolated from leaves and pods showing disease symptoms. However, Kochs postulates were fulfilled only for fungi belonging to the Colletotrichum genus. Fungi from the other seven genera did not produce disease symptoms in healthy AYB tissues. Several Colletotrichum isolates were characterized by sequencing the ITS, glyceraldehyde-3-phosphate dehydrogenase, calmodulin, and ApMAT loci. A combined phylogenetic analysis revealed four Colletotrichum species: C. siamense, C. theobromicola, and C. fructicola, which were recovered from the diseased leaves, and C. truncatum, which was recovered from diseased pods and buds. Our results are useful to gear efforts to develop integrated management strategies to control diseases affecting AYB in Nigeria and other parts of Africa. The availability of such strategies may stimulate greater cultivation of AYB to contribute to diet diversification, which has been repeatedly advocated by a range of stakeholders to increase food security and the prosperity of smallholder farmers.

microbiology↗