Comparative analysis of phylogenetic relationships, morphologies, and pathogenicities among Curvularia lunata isolates from maize in China

Global invasive Cochliobolus species: cohort of destroyers with implications in food losses and insecurity in the twenty-first century

Matching the global food demand by 2050 and to ensure the stability of food security in over than 99 countries, it is necessary to scale up the production of food such as sorghum, wheat, rice, maize and sugarcane which are however natural hosts of Cochliobolus species. Cochliobolus species major epidemics such as the Great Bengal famine, Southern corn leaf blight, and Northern leaf spot blight were associated with substantial economic losses in the past decades. Thus, there is an urgent need to establish a specific coordinated global surveillance program for the migration of invasive Cochliobolus species, planning contextual control programs engaging all agricultural stakeholders and information sharing in real time for prevention of disastrous Cochliobolus disease outbreak effects. We discuss pertinent outcome of interactions of cash crops with Cochliobolus species having devastating impact on the livelihood of farmers and food security. While post-genomic era elucidated prominent differences among Cochliobolus heterostrophus, C. carbonum, C. victoriae, C. lunatus and C. miyabeanus, their destructive potentials and implications in food losses remained unearthed. Intriguingly, the annual colossal losses caused by Cochliobolus species in the production perspective of sorghum, wheat, rice, maize, cassava and soybean is estimated over 10 billion USD worldwide. This paper provides a comprehensive analysis of the invasive Cochliobolus species distribution and diversity, evolving pathogenicity, persistent diseases, threats and epidemics, consequences on food crops production and increasing global food insecurity issues.

Clg2p interacts with Clf and ClUrase to regulate appressorium formation, pathogenicity and conidial morphology in Curvularia lunata

Ras is a small GTPase that regulates numerous processes in the cellular development and morphogenesis of many organisms. In this study, we identified and functionally characterized the Clg2p gene of Curvularia lunata, which is homologous with the Ras protein. The Clg2p deletion mutant (ΔClg2p) had altered appressorium formation and conidial morphology and produced fewer, smaller lesions compared with the wild-type strain. When a dominant Clg2p allele was introduced into the mutant, all of these defective phenotypes were completely restored. To further understand the regulation of Clg2p in appressorium formation and conidial morphology, and its role in pathogenicity, seven Clg2p-interacting proteins were screened using a yeast two-hybrid assay. Two of these proteins, Clf, a homologue of Mst11, which corresponds to MAP kinase kinase kinase in Magnaporthe oryzae, and urate oxidase (designated ClUrase) were functionally characterized. Clg2p specifically interacted with Clf through its RA domain to regulate appressorium formation and pathogenicity, whereas the Clg2p-ClUrase interaction regulated conidial morphology without affecting fungal pathogenicity. This report is the first to elucidate the regulatory mechanism of the key Ras protein Clg2p in C. lunata.