Mar 26, 2019Genomics reveals secrets of optimal harvest, storage
The study of genomics is yielding useful information for preventing conditions such as soft scald and bitter pit in fruit.
Genomics, “the study of genes, their sequence, structure, function, evolution and their expression,” helps to reveal a useful blueprint, like an instruction manual for fruit, explained Nigel Gapper, global genomics leader for AgroFresh, who works in Wenatchee, Washington.
Speaking at the recent Washington State Tree Fruit Association’s annual meeting and Northwest Horticultural Expo in Yakima, Washington, Gapper highlighted how “plants need to respond rapidly to their ever-changing environment.” By understanding how “different genes switch on and off in response to different environmental impacts,” growers can help to optimize everything from harvest time to storage procedures, he suggested.
AgroFresh, based in Philadelphia, specializes in “higher-quality yields and better harvest management.” Thus far, they have focused on apple crops, but hope to expand to additional types of produce.
Through intricate studies of an apple’s tens of thousands of genes, including more than 300 genes which regulate ethylene in the fruit, researchers can narrow down specifics on harvest and storage recommendations. They look at everything from starch metabolism to cell wall metabolism and “stress response pathways,” Gapper said. More than 20,000 genes can change during a single day.
To study the genes, the fruit is peeled, the peel is juiced and then a spot applied to a sampling card.
Researchers also track everything from the time of day fruit is harvested, to how long the fruit is in transit and how it is treated at receiving. In 2017, for example, blocks of Honeycrisp apples were monitored, at hundreds of sites in the Pacific Northwest and on the East coast. Pilot results, which included sampling fruit as often as every two hours, showed that the risk of soft scald increased as the days progressed from early harvest to late harvest.
Now, by studying gene expression, researchers have been able to predict with 96 percent accuracy which fruit is at low risk for soft scald. These predictions also may help to determine whether apples should go through a “conditioning” process, spending 10 days at a 50-degree temperature after harvest and before being placed in controlled atmosphere storage. Fruit at low risk may be kept in storage longer, while higher-risk fruit might be sold before soft scald could develop, Gapper said.
Bitter pit testing is still in an early stage, with more detailed research expected to launch later this year.
“We (are working to) predict storage problems before they happen,” Gapper said. While strides were made in soft scald research for Honeycrisp in 2018, 2019 research is expected to focus on prevention of bitter pit for Honeycrisp, internal browning for Gala and superficial scald for several apple varieties.
“It really is the tip of the iceberg and apples are really just the tip of the iceberg,” Gapper said in a later conversation with Fruit Growers News. Genomics has the potential to affect storage disorders, pathogens and food safety for the entire industry, he said.
— Christine Corbett Conklin, FGN correspondent; top photo courtesy of Cornell University