Evaluation of tolerance to Phytophthora cinnamomi Rands in avocado germplasm Persea americana Miller

Abstract

Twenty one accessions from the Avocado Germplasm Bank of CORPOICA, Palmira Research Station, were evaluated with two pathogenic strains of the oomycete, Phytophthora cinnamomi Rands. The objective of this project was to identify avocado accessions that could be potentially used as rootstocks as a cultural control strategy for preventing root rot disease. Disease progression was evaluated by using mycelium of the pathogen by cut-stem inoculation. The length and width of symptom progression were measured periodically. These data were used to calculate the area under the disease progression curve (AUDPC). A randomized complete block design (RCBD), with a factorial design of 3 x 21 in subdivided parcels (two strains of the pathogen, a control strain, and 21 avocado accessions) was used. Eight readings were taken per plant through time. Statistical analysis showed significant differences using the AUDPC for some avocado accessions. Tukey's test revealed five tolerance levels. Accession ‘NATU-001’ from Tumaco, Nariño, was identified as promising for its high tolerance and ‘CANO-008’ from Norcasia, Caldas, as a tolerant control accession had the second lowest value of AUDPC. Susceptible accessions used as control, e.g. ‘Hass’ variety and rootstock ‘Topa-Topa’, had very high susceptibility to the pathogen along with ‘QUIQUI-030’ accession from Quimbaya, Quindío, Colombia

Rosellinia necatrix infection induces differential gene expression between tolerant and susceptible avocado rootstocks

“…Currently, there are commercial rootstocks with partial tolerance/resistance to P . cinnamom i (‘Thomas’, ‘Duke 7’ and ‘Dusa’), and significant efforts are in progress to select material with enhanced tolerance and other agronomic traits [3]. In addition, investigations are underway to gain a better knowledge of the avocado- P .…”

Relaciones fisiológicas entre la maduración del fruto y las semillas de tomate de árbol (Solanum betaceum Cav.)

“…Estrategias de manejo: Una de las mejores estrategias para el manejo de la pudrición radical por P. cinnamomi es el uso de patrones tolerantes a la enfermedad en Colombia, como por ejemplo las accesiones 'NATU-001' y CANO-008' (Rodríguez-Henao, Caicedo-Arana, Enríquez-Valencia, & Muñoz-Flórez, 2017). La fumigación al suelo con harina de las semillas de Brassica carinata y B. juncea permite el control del patógeno y sus estructuras de resistencia debido a su alto contenido de sinigrina (Ríos et al, 2018).…”

Development and validation of severity scales of avocado wilt complex caused by Phytophthora cinnamomi, Verticillium dahliae and hypoxia-anoxia disorder and their physiological responses in avocado plants

“…Therefore, the causal agents and disorders involved are difficult to identify under traditional diagnostic practices, especially in the first stage of development of the disease. This may lead to erroneous management practices that worsen the problem and cause large economic losses (Ramírez-Gil et al, 2017;Rodríguez et al, 2017;Hardham and Blackman, 2018;Ramírez-Gil, 2018;Ramírez-Gil and Morales-Osorio, 2019). AWC can affect various tissues in the avocado, especially the roots, inducing several symptoms.…”

“…The fungus Verticillium sp. has been less studied, but has been increasingly recognized as important because of problems of root rot associated with the disorder hypoxia-anoxia, especially under tropical conditions in Colombia (Ramírez-Gil et al, 2017;Rodríguez et al, 2017;Ramírez-Gil, 2018;Ramírez-Gil and Morales-Osorio, 2019). Hypoxia-anoxia is not only considered a disorder that causes the death of avocado plants, but it can also be a stress factor that is highly related to the presence of P. cinnamomic (Stolzy et al, 1967;Ploetz and Schaffer, 1989;Sanclemente et al, 2014;.…”