Print version ISSN 1405-3195
ALARCON-RODRIGUEZ, Norma M.; LOZOYA-SALDANA, Héctor and VALADEZ-MOCTEZUMA, Ernestina. Characterization of DNA of potato clones and identification of phytoplasms associated with purple top syndrome. Agrociencia [online]. 2009, vol.43, n.4, pp. 357-370. ISSN 1405-3195.
In many potato growing areas in México, there is presence of purple top syndrome, which reduces the yield and quality of this tuber. A main factor of this syndrome is the presence of phytoplasms and inadequate management of its insect vector. One option for controlling this disease is to generate resistant potato genotypes and early diagnosis to prevent its disemination. Therefore, the objectives of the present study were to detect phytoplasms associated with purple top present in asymptomatic potato clones, but which were exposed to the disease for four seasons, and to identify the host-pathogen relationship. At the end of the 2005 growing season, leaves of 18 asymptomatic potato clones, in Toluca, State of México, were collected, originating from two breeding programs of the United States Department of Agriculture (USDA/ARS). Also included were the Alpha cultivar with symptoms of the disease as positive control and plants free of phytoplasm. The detection of the pathogen was made with direct PCR, nested PCR and RFLP markers, using the enzymes Alu 1, Hinf 1, Kpn 1, Eco R1, Tru 9, Taq 1, and identifying the presence of three groups of phytoplasm in all of the clones. The clones were clustered in three groups related to the positive control, using five primers of RAPDs markers. A limited specific host-pathogen relationship was detected as a function of the DNA fingerprints of both host and pathogen.
Keywords : Purple top; genetic resistence; RAPDs; RFLP.