Alterations induced by Avocado sunblotch viroid in the postharvest physiology and quality of avocado ‘Hass’ fruit

Abstract

Avocado sunblotch viroid (ASBVd) is an economically important pathogen that reduces the yield and quality standards of infected avocado trees. There are no reports on the effects of the viroid in the postharvest quality of avocado fruits. The present study has focused on three phenotypic classes: asymptomatic fruits harvested from vigorous trees (AF-V), asymptomatic fruits harvested from trees of regular vigor (AF-R) and symptomatic fruits harvested from trees expressing the disease (SF-S). The water loss was similar in the three fruit classes. The abnormal firmness condition, skin color and size reduction occurred only in SF-S fruits, which did not ripe uniformly due to reduced CO 2 and ethylene production. The proximal analyses showed no significant differences in the variables analyzed, except for the lipid content and dry matter, which was lower in SF-S and AF-R fruits. ASBVd affects physiology and postharvest quality of symptomatic avocado fruits. In contrast, the ripening process of AF-V and AF-R fruits was normal and their physical characteristics and nutrient input were not altered, therefore, these fruits were classified as Supreme Quality, Extra Size (221-265 g) and Premium (172-210 g) according to the NMX-FF-016-SCFI-2006 standards.

The Avocado Sunblotch Viroid: An Invisible Foe of Avocado

“…The most typical symptom on fruits is sunken crevices of white, yellow, or reddish color (Figure 2A) [25,26]. On severely affected fruits, the sunken areas may become necrotic (Figure 2F) [27,28]. The bases of some shoots and young branches of infected trees may show discolored streaks or stripes (Figure 2B).…”

“…ASBVd symptomatic fruits are disqualified for human consumption during the packing process, generating important postharvest losses. Postharvest physiology studies about the effects of ASBVd in fruits indicate a reduction in ethylene and CO 2 production, which causes a delay in fruit maturation, an effect that becomes more evident for symptomatic fruits [28]. Nevertheless, the weight loss, coloration changes, fruit size, mineral content and proximate analysis (protein, carbohydrates dietary fiber, and total ash) were similar in asymptomatic and control fruits.…”

“…The lipid content is affected by ASBVd, but these fruits exceed the minimum required value for the quality standards (22% of dry matter and 8% oil). Symptomatic avocado fruits still fulfill the minimum requirements to be industrialized [28,54]. The ASBVd may induce anatomical and chemical changes in the cellular structure, more evident in the symptomatic tissues, including cellular disorganization, accumulation of phenolic compounds in the cytoplasm and cell walls, and reduction of chlorophyll and cytoplasmic content that may be conducive to cell collapse (Figure 3) [27,28].…”

Expresión diferencial de genes de defensa en aguacate en respuesta a la infección del viroide de la mancha de sol del aguacate

“…Esta enfermedad causa efectos citopáticos y cambios fisiológicos (Di Serio et al, 2013;SaucedoCarabez et al, 2014;Vallejo-Pérez et al, 2014;Saucedo-Carabez et al, 2015;Vallejo-Pérez et al, 2015), que finalmente resultan en frutos de menor tamaño y calidad externa e interna, y con menor rendimiento de fruto. En los frutos, los daños severos incluyen heridas deprimidas en su superficie que varían desde un color amarillo hasta manchas necróticas (Desjardins, 1987).…”

“…Avocado sunblotch causes cytopathic effects and physiological changes (Di Serio et al, 2013;Saucedo-Carabez et al, 2014;Vallejo-Pérez et al, 2014;Saucedo-Carabez et al, 2015;Vallejo-Pérez et al, 2015) that result in smaller fruit, low external and internal quality and reduced yield. Severe damages on fruit include depressed wounds on the surface with yellow to necrotic spots (Desjardins, 1987).…”