Chile is one of the worlds largest producers of avocados contributing to its economy growth. Increased production and international competition, in addition to changes in production conditions, require Chilean producers to focus on developing competitive advantages. Recently, a new problem for Chilean Hass exported avocado has appeared and it is known as black spot, which caused rejections of up to 20%. The causes of this disorder are still unknown and sometimes associated to physiological or pathological disorders. The symptoms visible after storage are variable and the causes of the black spot symptoms are not known in the literature and there is no scientific consensus regarding the causesof black spot disorder in avocado.
Preliminary work of our group at PUCV has analyzed fruit from orchards from different agro-ecological regions during the season 2017/2018 and recorded different incidence of black spot associated to climatological conditions and to the defense mechanisms of the fruit. A deep study for better understanding the causal factors of black spot is needed.
In this project we hypothesized that black spot development in Hass avocado epidermis is driven by an imbalance of oxidative stress markers and antioxidant defense system. Thus, the main objectives of this proposal are to evaluate the balance/imbalance between oxidative stress markers and antioxidant defense systems of Hass avocado epidermis at different levels (enzymatic, transcriptomic and metabolomic) and its correlation to black spot development under different scenarios.
We will use a metabolomics approach (GC-MS, HPLC and transcriptomics) to monitor changes in antioxidant defense system, reactive oxygen species and fruit quality parameters of stored Hass avocado combined with chemometrics for data integration. Fruits from 2 different orchards (high and no incidence of black spot based on historical data) during two subsequent harvests and two different seasons (early and late season) will be collected and stored in two different storage conditions for subsequent laboratory analyses.
The results of this study are expected not only to provide more foundation into the biochemical processes associated to black spot of Hass avocados but also provide potential biomarkers involved in this disorder, which may help to implement postharvest protocols to reduce this problem in practice. Important variables or biomarkers found will be also used in model building to predict black spot development during storage. This project will generate scientific and academic publications, extension and training of young researchers and will strengthen the network with our national and international key partners. The findings of this project will help growers, agronomists, and packing houses achieve significant cost savings during postharvest handling and storage of avocados.