|Brown, Charles - Chuck|
|Grunwald, Niklaus - Nik|
Submitted to: Mexican Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2002
Publication Date: 11/15/2002
Citation: LOZOYA-SALDANA, H., HERNANDEZ-VILCHIS, A., GARAY-SERRANO, E., BROWN, C.R., GRUNWALD, N.J., HELGESON, J.P. GENETIC STUDIES AND BREEDING OF STABLE LATE BLIGHT RESISTANCE OF POTATO IN THE UNITED STATES AND MEXICO. MEXICAN JOURNAL OF PHYTOPATHOLOGY. 19(2):253-260. 2002. Interpretive Summary: Late blight, a severe disease of potato, caused by a water mold, is important throughout the world. It costs $100 million a year in the United States to control this disease. It results in foliage death and can cause extensive tuber rot in storage if the tubers become infected during the growing season. Effective use of fungicides is the current method of control, but current cultivars differ slightly in susceptibility and this can help a lot. The breeding research in Mexico on resistance is located in the probable birthplace of the disease organism, the Toluca Valley. The pathogen is extremely variable there and tends to break down most types of resistance except so-called durable resistance. Durable resistance consists of many components that work together to slow down the disease development no matter what the genetic variation in the pathogen is like. Recent changes in the late blight organism which have revived fears of an Irish Potato Famine-like crop failure in the US have emerged right out Mexico. US scientists are therefore breeding for the future by exposing the potato breeding clones to late blight in the Toluca Valley, anticipating the next attack by the potatoes most serious enemy.
Technical Abstract: The Toluca Valley of Mexico is the putative center of origin of Phytophthora infestans. This oomycete shows tremendous variability found no where else in the world. It is an excellent site to test for durable resistance in potato. During a five year period breeding materials derived from highly diverse breeding populations have been tested in successive years. Clones derived from Solanum bulbocastanum, S. hougasii, and materials derived from the Polish Breeding Program with numerous wild and cultivated progenitors have been found to have partial field resistance that is effective in limiting disease and has not been diminished in a significant way over the years. Several clones derived from the US representing Polish ancestry, S. bulbocastanum were compared to locally bred blight resistant varieties both for resistance and the diversity of the late blight organism. It was found that the US breeding materials showed comparable resistance over two years testing. Isolation of late blight cultures failed to show differentiation of late blight genotypes on the US versus the Mexican clones either in overall diversity or uniqueness. The stability of resistance and lack of evidence of selection by the host for new genotypic diversity or greater virulence of the pathogen augurs well for the durability of the US sources of resistance. There use as parents will most likely lead to new varieties with non-race-specific resistance to late blight in the future.