An Institute of Food Research scientist has made a discovery concerning the flesh of mature Fuji apples that could prove a breakthrough in storage of the variety.
Mary Parker discovered clumps of previously unreported callus hairs growing in the flesh of mature Fuji apples and closely-related varieties. “To find out something new about apples is really exciting,” said Dr Parker. “The reason these hairs have not been spotted before is probably because the full extent of their growth can only be appreciated in 3D.”
Dr Parker used light microscopy and scanning electron microscopy to reveal clumps of small, elongated and branched cells in the air spaces between cells. She named them callus hairs because of their resemblance to the cells which make up the white velvety tufts (sometimes mistaken for fungus) which develop around the seeds in some apple varieties.
The presence of callus hairs filling the airspaces of mature Fuji could account for the susceptibility of late-harvested apples to internal browning. Unrestricted gas flow through the fruit is vital for successful long-term storage particularly in modified atmospheres. Callus hair growth, with its own oxygen requirement and carbon dioxide output, may reduce the efficiency of gas transport through the spaces between cells.
“With this new knowledge, breeders could pick parent varieties with all the positive traits of Fuji apples but with less-developed callus hairs”, she said. Preliminary studies have shown that callus hairs are rich in phytonutrients but may also contain allergens. Further investigation is now needed to establish how growth conditions and orchard management affect the extent of callus hair development, added Dr Parker.
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