Insights into Blossom End-Rot Disorder in Tomato (Solanum lycopersicum)

Blossom end rot (BER) is mainly a calcium (Ca²⁺) deficiency-related physiological disorder of fruits that affects various crop production worldwide including tomato (Solanum lycopersicum). The visible symptoms of BER include cell wall disintegration, cell plasmolysis, and water-soaked signs at the distal end of the fruits. During fruit development increase in cell expansion and a decrease in the transport of Ca²⁺ to the distal part of the fruits, can lead to the development of BER. It is hypothesized that insufficient Ca²⁺ is available for essential apoplastic and cytoplasmic functions during the cell expansion phase of fruits when the cellular Ca²⁺ demand exceeds the Ca²⁺ supply. Therefore, abnormal intracellular Ca²⁺ content or signals, cause weakening of cell walls, and a loss of cellular integrity, potentially leading to cell death and the outward manifestations of BER. The occurrence of BER in tomatoes is also influenced by environmental factors that affect the cellular growth of the fruits. These factors such as drought, high salinity, high temperature, insufficient xylem tissue development, phytohormones, and oxidative stress can influence the development of BER. The availability of a high-quality reference genome and whole genome sequencing allowed us to identify selected loci that can cause BER, facilitating genetic dissection and a deeper comprehension of the molecular mechanisms underlying this disorder. This review summarized the various factors and genes involved in BER development and management strategies.