Exogenous systemin has a contrasting effect on disease resistance in mycorrhizal tomato (Solanum lycopersicum) plants infected with necrotrophic or hemibiotrophic pathogens.
A study was performed to determine the effect of the systemin polypeptide on the bio-protective effect of arbuscular mycorrhizal fungi (AMF) in tomato plants infected with Alternaria solani, Phytophthora infestans or P. parasitica. Before infection, tomato plants were colonized with two different AMF, Glomus fasciculatum or G. clarum. In addition, a group of inoculated plants was treated with systemin, just after emergence. The exogenous application of systemin marginally suppressed the resistance against A. solani leaf blight observed in G. fasciculatum mycorrhizal plants but significantly enhanced it in plants colonized with G. clarum. Systemin induced resistance to P. parasitica in leaves of G. fasciculatum mycorrhizal plants, in which AMF colonization alone was shown to have no protective effect. Conversely, none of the treatments led to resistance to root or stem rots caused by P. infestans or P. parasitica. The above effects did not correlate with changes in the activity levels of beta-1,3-glucanase (BG), chitinase (CHI), peroxidase (PRX), and phenylalanine ammonium lyase (PAL) in leaves of infected plants. However, they corroborated previous reports showing that colonization by AMF can lead to a systemic resistance response against A. solani. Systemic resistance to A. solani was similarly observed in non-mycorrhizal systemin-treated plants, which, in contrast, showed increased susceptibility to P. infestans and P. parasitica. The results indicated that the pattern of systemic disease resistance conferred by mycorrhizal colonization was dependent on the AMF employed and could be altered by the exogenous application of systemin, by means of a still undefined mechanism.
de la Noval
Blanca
B
Instituto Nacional de Ciencias Agrícolas (INCA), Carretera de Tapaste, Km. 3.5, Gaveta Postal 1, 32700, San José de las Lajas, La Habana, Cuba.
Pérez
Eduardo
E
Instituto Nacional de Ciencias Agrícolas (INCA), Carretera de Tapaste, Km. 3.5, Gaveta Postal 1, 32700, San José de las Lajas, La Habana, Cuba.
Martínez
Benedicto
B
Centro Nacional de Sanidad Agropecuaria (CENSA), Carretera de Tapaste, Km. 3.5, Gaveta Postal 1, 32700, San José de las Lajas, La Habana, Cuba.
León
Ondina
O
Instituto Nacional de Ciencias Agrícolas (INCA), Carretera de Tapaste, Km. 3.5, Gaveta Postal 1, 32700, San José de las Lajas, La Habana, Cuba.
Martínez-Gallardo
Norma
N
Unidad de Biotecnología e Ingeniería Genética de Plantas del Cinvestav-Campus Guanajuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León. Apartado Postal 629, 36500, Irapuato, Gto., Mexico.
Délano-Frier
John
J
Unidad de Biotecnología e Ingeniería Genética de Plantas del Cinvestav-Campus Guanajuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León. Apartado Postal 629, 36500, Irapuato, Gto., Mexico. jdelano@ira.cinvestav.mx.
D000528:Alternaria / Q000254:growth & development*; D002688:Chitinases / Q000032:analysis; D005658:Fungi / Q000254:growth & development*; D043326:Glucan 1,3-beta-Glucosidase / Q000032:analysis; D007113:Immunity, Innate / Q000187:drug effects*; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000382:microbiology*; D010455:Peptides / Q000494:pharmacology*; D009195:Peroxidase / Q000032:analysis; D010650:Phenylalanine Ammonia-Lyase / Q000032:analysis; D010838:Phytophthora / Q000254:growth & development*; D010935:Plant Diseases / Q000276:immunology*; D018515:Plant Leaves / Q000737:chemistry / Q000382:microbiology
D010455:Peptides; C073704:systemin; D009195:Peroxidase; D002688:Chitinases; D043326:Glucan 1,3-beta-Glucosidase; D010650:Phenylalanine Ammonia-Lyase