Biology subjects

Afolabi, C. G.

Publications and source records attributed to Afolabi, C. G..

2 recordsLinked to original sources

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↗

bioRxiv2020

Testing for the resistance of newly generated hybrid cacao germplasm in the gene pool of Cocoa Research Institute of Nigeria (CRIN) against Phytophthora megakarya pathogen causing black pod disease of cocoa.

Black pod disease caused by P. Palmivora and P. megakarya is an important disease affecting cacao in West Africa which produces 70% of the world output. Resistance to the pathogen is therefore, an important factor to be considered when breeding for high yielding and earliness in fruiting. Resistance to the pathogen using Leaf Disc Test (LDT) was conducted at the Plant Pathology Laboratory, Ibadan, on detached 15mm diameter discs of two-month-old leaves obtained from nineteen newly generated cacao hybrids in the gene pool of the Institute. Attached Whole Leaf Test (AWLT) was also conducted on few selected hybrids in the screen house at the same institute. Ten l zoospores suspension of P. megakarya pathogen adjusted to inoculum strength of 3x105 zoospores/ml using haemocytometer was used for the inoculation of the cacao LD. Using 0-5 disease rating scale, data was taken on the 5th and 7th day after inoculation for LDT and on the 6th day after inoculation for AWLT. Data obtained were subjected to Analysis of Variance and significant means were separated using Student Newman Kuels Test at p<0.05. The LDT classified the hybrids into five groups namely: Resistant (hybrid 001, 003 and 005); Moderately Resistant (hybrid 006, 007, 008,013,015,018 and 019) Moderately Susceptible (hybrid 004, 014 and 017); Susceptible (hybrid 002, 010, 011 and 016) and Highly Susceptible (hybrid 009 and 012). Scores from LDT significantly correlated (r= 0.92**) with that of AWLT. It was observed from the study that cacao hybrid 001, 003 and 005 showed traits of resistant and therefore, could be incorporated into the national breeding programs for the development of high-yielding and resistant cacao cultivars. The moderately resistant hybrids could be conserved for future germplasm enhancement program.

pathology↗