Stem canker caused by Phomopsis spp. induces changes in polyamine levels and chlorophyll fluorescence parameters in pecan leaves

MANTZ GUILLERMO MARTÍN; ROSSI FRANCO RUBÉN (CO-FIRST AUTHOR); VIRETTO PABLO ESTEBAN; NOELTING MARÍA CRISTINA; MAIALE SANTAGO JAVIER

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2021 vol. 166 p. 761 - 769

0981-9428

Pecan plants are attacked by the fungus Phomopsis spp. thatcauses stem canker, a serious and emerging disease in commercial orchards. Stemcanker, which has been reported in several countries, negatively affects treecanopy health, eventually leading to production losses. The purpose of thisstudy was to inquire into the physiology of pecan plants under stem cankerattack by Phomopsis spp. To this end, pecan plants were inoculated withan isolate of Phomopsis spp. and several parameters, such as polyamines,proline, sugars, starch, chlorophyll fluorescence and canopy temperature wereanalysed. Under artificial inoculation, a high disease incidence was observedwith symptoms similar to those in plants showing stem canker under fieldconditions. Furthermore, the infected stem showed dead tissue with brownnecrotic discolouration in the xylem tissue. The free polyamines putrescine,spermidine, and spermine were detected and their levels decreased as leavesaged in the infected plants with respect to the controls. Chlorophyll fluorescenceparameters, such as Sm, ψEO, and QbRC decreased under plant infection andtherefore the K-band increased. Canopy temperature and proline contentincreased in the infected plants with respect to the controls while sugarcontent decreased. These data suggest that stem canker caused by Phomopsisspp. induces physiological changes that are similar to those observed inplants under drought stress. To our knowledge, this is the first study thatdocuments the physiological and biochemical effects derived from pecan-Phomopsisinteraction.