Link to home

​2024 Fellow: Marcial Pastor-Corrales​

Marcial A. Pastor-Corrales, “Talo," was born in Arrozal, Northern Peru. He earned a B.S. degree (1972) in botany; an M.S. degree (1974) in botany/mycology from Eastern Illinois University; and an M.S. degree (1977) and a Ph.D. degree (1980) in plant pathology from Texas A&M University. In 1980, Talo joined the International Center for Tropical Agriculture (CIAT), Cali, Colombia, where he spent 17 years as a senior staff plant pathologist. He then worked for three years at Novartis Crop protection in Hudson, NY. In 2000, Talo accepted the USDA-ARS Research plant pathologist position at the Beltsville Agricultural Research Center in Maryland.

Talo is a world-renowned authority on common bean diseases and understanding their virulence spectrum, using genetic resistance to manage these diseases, and the development of common bean cultivars with durable resistance.

At CIAT, he studied the virulence diversity of the anthracnose and angular leaf spot (ALS) pathogens in Latin America. He collected hundreds of isolates of these pathogens and developed two new sets of differential cultivars containing cultivars from the Andean and Mesoamerican gene pools of the common bean to study their virulence spectra. He uncovered an extensive virulence diversity of both pathogens that segregated into two distinct virulence groups, named Mesoamerican and Andean. The Mesoamerican races infected Mesoamerican and Andean differential cultivars and had a broad virulence span, while the Andean races infected only Andean differential cultivars and had a narrow virulence span. These insightful findings suggested coevolution; Andean isolates of both pathogens would have coevolved with Andean beans in the highlands of South America, and Mesoamerican isolates would have evolved with Mesoamerican beans in Mexico and Central America.

At USDA-ARS, Talo initiated similar research into the virulence diversity of the bean rust pathogen. He developed a new set of differential cultivars, also containing Andean and Mesoamerican differential cultivars, to characterize the virulence spectrum of the rust pathogen. He adopted a binary system to name the newly identified races, providing virulence information for each race. This led to the characterization of 43 old races that separated into two virulence groups—Andean and Mesoamerican. His pioneering research identified three distinct fungal pathogens of common bean with shared virulence patterns and large virulence diversity that separated into two distinct virulence groups.

Based on these findings, Talo next launched collaborations with scientists from U.S. universities and other countries to identify new resistance genes and develop molecular markers for the creation of new common beans combining both broad and effective resistance with desirable agronomic traits. Together, they have registered 22 cultivars/germplasm lines in the Journal of Plant Registrations. Among these, Talo developed six great northern common bean germplasm lines that contained four rust resistance genes along with two viral resistance genes, conferring resistance to all known races of the bean rust pathogen and to all known strains of the Bean common mosaic and Bean common mosaic necrosis viruses.
Following the first report in 2004 of the soybean rust pathogen in the United States and the report in 2005 that this pathogen was infecting common beans in South Africa, Talo studied the response of common bean cultivars to six isolates of the soybean rust pathogen from Asia, Africa, and South America in collaboration with ARS scientists at Ft. Detrick, MD. Subsequently, Talo identified common cultivars with high levels of resistance to all isolates of the soybean rust pathogen.

After the publication in 2014 of the reference genome of the common bean and the development of high-throughput genotyping technologies, Talo used genomics and related technologies, including fine mapping, to develop highly accurate molecular markers tagging common bean disease resistance genes. He first published the fine mapping of the historically important Ur-3 rust resistance gene. This was followed by the fine mapping of seven rust and three anthracnose resistance genes and the development of single sequence repeat makers, single nucleotide polymorphism, and Kompetitive allele-specific PCR markers. Based on his research findings, U.S. bean breeders have developed commercial common bean cultivars with high levels of disease resistance.

Recently, Talo collaborated with a scientist from Sri Lanka to study the virulence of the bean rust pathogen infecting snap beans. Together they published the first races of the rust pathogen in Sri Lanka and the development of a snap bean cultivar containing the Ur-11 rust gene conferring resistance to all known races of this pathogen in Sri Lanka.

Talo has been a very active APS member, contributing significantly and consistently to our society. He was a member of the Office of International Programs (OIP) for 20 years and served twice as director of OIP, chair of the OIP International Travel Fund, the OIP John and Anne Niederhauser Endowment Fund, and OIP Advisory Board Member. Internationally, Talo served as an associate editor of the Tropical Plant Pathology Journal and as a member of the editorial board of Acta Scientiarum, an agronomy journal, both from Brazil. Talo has been a member of the following organizing committees: the 5th International Conference on Plant Pathogenic Bacteria, the Joint XXII Meeting of the APS Caribbean Division with the V Congress of the Colombian Phytopathology Society, the Joint XXIX Triple Meeting of the APS Caribbean Division with the 10th Congress of the Colombian Phytopathology Society and the 5th Congress of the Latin American Phytopathological Association. In the United States, Talo has been the secretary of the W-2150 (Genetic Improvement of Beans [Phaseolus vulgaris L.] for Yield, Disease Resistance, and Food value) and a member of the organizing committee for the Advanced Phaseolus Bean Research Network.

Talo is considered by the international community as an expert in the identification and characterization of new virulence spectra of plant pathogens infecting common bean, in the discovery of disease resistance genes, and in the development of durable resistant, commercial bean cultivars. His outstanding service to APS makes him worthy of recognition as an APS Fellow.​