Fruit softening is a key component of ripening, causing the damage and loss in the fruit food supply chain. It has thus become a scientific and industrial hotspot in the field of post-harvest biology, storage and logistics.
Modern breeding often sacrifices fruit quality, such as flavor, aroma and nutrition. Biotechnology has become an important pathway to improving agronomic traits of fruit. One of the most common strategies is to modify ethylene emission, such as antisense of ACS/ACO. RIN (ripening inhibitor) hybrid fruit (RIN/rin) can delay the ripening process and prolong shelf life by reducing the synthesis of ethylene, but it leads to the loss of favor, aroma and nutrition. It is thus essential to regain traditional flavor and improve fruit quality.
This work was led by Prof. CHEN Kunsong from Laboratory of Fruit Quality Biology in Zhejiang University, and Prof. James J. Giovannoni from Boyce Thompson Institute. A novel ripening-specific LATERAL ORGAN BOUNDRIES (LOB) domain transcription factor was functionally characterized and published in PNAS.
Gene expression and phenotypes following SlLOB1 repression
Their research revealed that SlLOB1 can up-regulate a suite of cell wall-associated genes during late maturation and ripening of locule and pericarp tissues. Silencing SlLOB1 can impede softening while producing no side-effect on the natural ripening and softening process. SlLOB1 overexpression can activate downstream cell wall genes and thereby induce premature softening.
Unlike other softening regulators, SlLOB1 participates in a regulatory subcircuit predominant to cell wall dynamics and softening independent of ethylene. Moreover, it can promote the accumulation of lycopene.
"Our study offers a key target for delaying fruit softening, extending shelf life and ensuring nutrition during breeding," said Chen. "It also opens up a new avenue to striking a balance between the amelioration of fruit firmness in storage and logistics and the improvement of fruit nutritional quality."
