Taro (Colocasia esculenta) is a major staple crop in Cameroon; since 2010, however, its production has been severely affected by taro leaf blight (TLB), caused by the oomycete Phytophthora colocasiae. To date, TLB remains the primary constraint to taro production, leading to significant yield losses and threatening food security and rural livelihoods. Despite its growing impact, little is known about the genetic diversity and population structure of this pathogen in Cameroon. To fill this gap, 67 isolates of P. colocasiae were collected from 9 localities (grouped into 5 populations) within major taro-producing regions of Cameroon and their ITS locus was sequenced. Genetic analyses revealed low diversity within and among populations, with seven haplotypes identified that differed at six polymorphic sites: four single-base substitutions and two deletions, one involving a single base and the other involving two bases. The haplotype network displayed a star-like pattern, characteristic of a recent range expansion. The central and most frequent ITS haplotype (shared by 52 Cameroonian isolates) was identical to sequences previously reported from Ghana and Nigeria in Africa; Chagos and India in South India; China and Taiwan in East Asia; Indonesia and Philippines in South-East Asia; as well as from Hawaii; whereas the second most frequent haplotype (shared by 9 Cameroonian isolates) was identical to sequences previously reported from Malaysia in South-East Asia and from Hawaii. These findings provide novel insights into the genetic diversity and population structure of P. colocasiae in Cameroon and underscore the urgent need for enhanced surveillance and integrated disease management strategies to mitigate the ongoing impact of TLB.
Microbe-associated molecular patterns (MAMPs) play a central role in activating plant immune responses. Bacillus velezensis A6 secretes elicitor molecules, such as flagellin and exopolysaccharides (EPS), that contribute to resistance to bacterial leaf spot caused by Xanthomonas euvesicatoria pv. perforans. In this study, flagellin and EPS were extracted and partially purified from B. velezensis A6 and biochemically characterized to evaluate their ability to prime host defense responses. Tomato seedlings (Solanum lycopersicum cv. Shivam) primed with flagellin (100 µg/ml) and EPS (20 µg/ml) exhibited reduced disease severity (6.79–7.24
Moko disease, caused by phylotype II strains of the Ralstonia solanacearum species complex (RSSC) historically known as “Race 2”, is one of the most important bacterial threats to banana production because of its lethality, soil persistence, and difficulty of eradication. To establish a national genomic surveillance baseline and characterize the identity, population structure, and geo-temporal patterns of the Moko pathogen, we analyzed 46 quality-controlled R. solanacearum genomes collected from Moko-affected banana (Musa AAA) plantations across four principal producing regions of Costa Rica, spanning 2010 to 2024. Whole-genome comparison against a reference panel of characterised Moko strains shows that all Costa Rican isolates belong to phylotype IIA, sequevar 6, sharing 100
