Abstract. Cano-Reinoso DM, Soesanto L, Kharisun, Wibowo C. 2021. Review: Fruit collapse and heart rot disease: Pathogen characterization, ultrastructure infections of plant and cell mechanism resistance. Biodiversitas 22: 2477-2488. Fruit collapse and bacterial heart rot are diseases in pineapple caused by Erwinia chrysanthemi (later classified as Dickeya zeae) which are increasingly prevalent in the last decade, causing devastating production loss in pineapple cultivation. Yet, comprehensive knowledge to tackle such diseases is limited, understandably due to the relatively new emerge of the diseases. Here, we review the causes of bacterial heart rot and fruit collapse, stages of infection, typical symptoms and the occurrence of resistance mechanisms in plants. In pineapple, the fruit collapse is noticeable by the release of juice and gas bubbles, also the shell of the fruit that turns into olive-green. Meanwhile, bacterial heart rot is characterized by water-soaked zones on the leaves, the formation of brown streaks on the lamina and in the mesophyll, and light-brown exudate in the blisters. The most common means of penetration into the host plant used by this type of pathogen is through plant natural openings, injuries and wounds, and entire surfaces. Concurrently, plants and fruits develop disease-resistant mechanisms to inhibit infection growth under this pathogenic attack. These mechanisms can be divided into hypersensitive reactions, locally acquired resistance, and systematic acquired resistance. In addition, pathological infections produce an interaction of the cell wall with pectolytic enzymes. Understanding the membrane breakdown process carried out by these enzymes has become critical to a pineapple protection plan. This review suggests that future research to tackle fruit collapse and bacterial heart rot can be focused on disease-resistant mechanisms, and their effects on the cell wall status with an enzymatic characterization.

Salicylic acid applied pre-and postharvest can impact positively the fruit quality, although more experiments are necessary to clarify its influence on pineapple. Therefore, this study aimed to evaluate the effect of pre-and postharvest treatments with salicylic acid on physicochemical properties of MD2 pineapple. Treatments were, A (Control: Waxing but without SA application pre-and postharvest), B (SA (2 mM) preharvest (sprayed) + SA (5 mM) postharvest (dipping)), C SA (2 mM) preharvest (sprayed) + SA (7 mM) postharvest (dipping)) and D (SA (2 mM) preharvest (sprayed) + SA (9 mM) postharvest (dipping)). Fruit total soluble solids, total acidity, ascorbic acid, β-carotene, fruit weight, percentage of weight loss, firmness, respiration rate, shell colour and flesh translucency were examined. The ascorbic acid, respiration rate and flesh translucency were determined as the variables more influential in this study. Treatments with postharvest concentrations higher than 5 mM increased the ascorbic acid (˃ 300 mg/kg) and reduced the translucency incidence (˂ 20 %), while with postharvest concentrations between 5-7 mM reduced the respiration rate (˂ 12 mL CO2/kg*h). All the treatments provided ideal values for the rest of the quality variables studied. Finally, treatment C was considered the most beneficial for the fruit, delivering the most elevated ascorbic acid content (385.89 mg/kg), the lowest respiration rate (10.46 mL CO2/kg*h) and translucency incidence (16.67 %). Keywords: Antioxidants, Ascorbic acid, Enzyme, Respiration rate, Translucency

No abstract

postharvest applications of Calcium and gibberellic acid have proved to maintain optimal fruit quality and control decay during cold storage. This study evaluated the effect of calcium and gibberellic acid dipping application on pineapple quality and internal browning. The experiment implemented two factors. The first factor concerning two dipping times (five and ten minutes) and the second factor related to four treatments, A (gibberellic acid), B (calcium), C (calcium + gibberellic), and control (D) - (no calcium or gibberellic acid applied). Total soluble solids (TSS), total acidity (TA), TSS/TA ratio, sugar, citric and ascorbic acid content, together with browning severity and incidence, were determined. Treatment B, essentially using a dipping time of five minutes, delivered the best performance having the lowest severity and incidence of browning (4.44 and 22.22 %, respectively), the highest citric acid (0.61 %), ascorbic acid content (405.18 mg kg-1) and TSS/TA ratio (25.53). Meanwhile, the other treatments were considered less satisfactory, due to their highest browning severity and incidence, without remarkable impact on the citric acid and ascorbic acid content, especially with a dipping time of ten minutes. In conclusion, dipping applications of calcium and gibberellic in postharvest enhanced pineapple quality and reduced the internal browning.

No abstract