Variability in Susceptibility to Anthracnose in the World Collection of Olive Cultivars of Cordoba (Spain)

Abstract

Anthracnose of olive (Olea europaea ssp. europaea L.), caused by Colletotrichum species, is a serious disease causing fruit rot and branch dieback, whose epidemics are highly dependent on cultivar susceptibility and environmental conditions. Over a period of 10 years, there have been three severe epidemics in Andalusia (southern Spain) that allowed us to complete the assessment of the World Olive Germplasm Bank of Córdoba, one of the most important cultivar collections worldwide.A total of 308 cultivars from 21 countries were evaluated, mainly Spain (174 cvs.), Syria (29 cvs.), Italy (20 cvs.), Turkey (15 cvs.), and Greece (16 cvs.). Disease assessments were performed using a 0–10 rating scale, specifically developed to estimate the incidence of symptomatic fruit in the tree canopy. Also, the susceptibility of five reference cultivars was confirmed by artificial inoculation. Because of the direct relationship between the maturity of the fruit and their susceptibility to the pathogen, evaluations were performed at the end of fruit ripening, which forced coupling assessments according to the maturity state of the trees. By applying the cluster analysis to the 308 cultivars, these were classified as follows: 66 cvs. highly susceptible (21.4%), 83 cvs. susceptible (26.9%), 66 cvs. moderately susceptible (21.4%), 61 cvs. resistant (19.8%), and 32 cvs. highly resistant (10.4%). Representative cultivars of these five categories are “Ocal,” “Lechín de Sevilla,” “Arbequina,” “Picual,” and “Frantoio,” respectively. With some exceptions, such as cvs. Arbosana, Empeltre and Picual, most of the Spanish cultivars, such as “Arbequina,” “Cornicabra,” “Hojiblanca,” “Manzanilla de Sevilla,” “Morisca,” “Picudo,” “Farga,” and “Verdial de Huévar” are included in the categories of moderately susceptible, susceptible or highly susceptible. The phenotypic evaluation of anthracnose reaction is a limiting factor for the selection of olive cultivars by farmers, technicians, and breeders.

INCIDENCE AND SEVERITY OF ANTHRACNOSE (Colletotrichum lindemuthianum) ON SELECTED COMMON BEAN (Phaseolus vulgaris L.) GENOTYPES

“…The analysis of variance of mean disease severity and incidence under field conditions revealed highly significant differences (P≤0.001) among the genotypes. The three regions of study showed site variations on incidence and severity among the genotypes and from these results therefore, it is evident that disease incidence and severity differs in different locations and this is in agreement with studies made by Moral et al 2017. From the results, Busia had high incidence and severity of anthracnose on the selected common bean genotypes, followed by Bungoma and University of Eldoret.…”

Olive anthracnose: a yield‐ and oil quality‐degrading disease caused by several species of Colletotrichum that differ in virulence, host preference and geographical distribution

“…The establishment of the Olive World Germplasm Bank in Córdoba (Spain) has enabled direct comparison of cultivars, contributing to the solution of homonymy and synonymy problems. It is a valuable source of germplasm which may help in the current expansion projects of the crop to other regions (Moral et al ., ). It also enables the performance of olive anthracnose resistance screening experiments.…”

“…Based on the same collection, Moral et al . () analysed 308 cultivars from 21 countries, 21% of which were classified as highly susceptible, 27% as susceptible, 21% as moderately susceptible, 20% as resistant and 10% as highly resistant. These authors selected cultivars as representative of each resistance class: ‘Ocal’, highly susceptible; ‘Lechín de Sevilla’, susceptible; ‘Arbequina’, moderately susceptible; ‘Picual’, resistant; ‘Frantoio’, highly resistant.…”

Impact of Colletotrichum acutatum Pathogen on Olive Phenylpropanoid Metabolism

“…Picual presented infection symptoms, on fruit mesocarp, only after 72 hai. The fruit ripeness increases the fruit susceptibility to pathogen infection, with the unripened (or developing) fruit being tolerant to the C. acutatum infection [9,13]. According to the total phenolic measures (Figure 3), the cultivars respond to the infection by increasing the level of phenols at 16 hai (crop year 2016) and 48 hai (crop year 2017) directly associated with the elicitation increases of the PAL enzyme activity (Figure 2).…”