Imagine living in a world where ripe tomatoes don’t shrivel, week-old grapes are always plump and the fruit drawer in the bottom of the refrigerator never smells musty.
Researchers at Purdue University in Indiana say it may not be far from reality.
Avtar Handa, a researcher and professor of horticulture at Purdue, has identified a process that can extend the shelf life of tomatoes by more than a week.
He thinks the process could also be used to extend the shelf lives of other fleshy fruits such as peaches, grapes and mangoes.
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“It could be especially effective on fruits that undergo rapid deterioration after ripening…. It would take much longer for them to undergo the wrinkling and aging process,” Handa said.
He and graduate student Savithri Nambeesan used genetic modification to isolate a yeast gene and add it to tomatoes.
The transplanted genes increased production of a compound known as spermidine, which delays deterioration in fruit, prolongs their nutritional value and improves processing quality.
Fully ripened genetically modified tomatoes lasted eight days longer than equally ripe tomatoes that did not contain the spermidine synthase gene.
Decay and rot symptoms associated with fungal growth were also delayed by three days.
“Most fruits, as they mature, begin to undergo disintegration, so we wanted to look at what can we do to improve the quality of fruit at that stage,” Handa said.
“Basically, we were trying to extend the fruit’s shelf life and improve fruit quality at that point because marketing is mostly done for ripe fruit.”
Spermidine is a type of polyamine, which is found in all living cells. However, its function is still not fully understood.
Scientists know polyamines are essential compounds that enable plants to perform basic biological functions such as cell division.
However, more research is needed before scientists understand the complex role of polyamines and their influence on genetic machinery.
Scientists have known about spermidine for many years, but research examining its relationship with aging and microbial decay in fruit has only recently gained the attention of the fresh fruit industry.
Spermidine occurs naturally in most fruit but rates of production vary between species. In most cases, spermidine levels decrease rapidly after ripening has occurred.
U.S. Department of Agriculture researcher Autar Mattoo said Handa’s work could have significant implications for the fresh fruit industry and for human nutrition in areas where access to fresh fruit is limited.
“Shelf life is a major problem for any produce in the world, especially in countries such as in southeast Asia and Africa that cannot afford controlled environment storage,” Mattoo said.
Additional polyamine research could lead to other discoveries that affect human health and commerce.
“At least a few hundred genes are influenced by polyamines, maybe more,” he said.
“We see that spermidine is important in reducing aging. It will be interesting to discover what other roles it can have.”
Handa said pubic acceptance of GM fruit and vegetables is still a stumbling block in many countries, but the development of new GM crops is still important, even if they do not gain immediate regulatory approval.
“I am in the business of discovering knowledge and I think that once that knowledge is there, other people could pick this idea up and do natural enhancements using other (non GM) techniques,” he said.
“It’s a big problem right now, getting approvals from regulatory agencies, but I think it’s a matter of finding proof of concept first, and once that proof of concept is there, then there may be many different ways you can accomplish the same thing, not only through genetic modification. Once we understand what’s going on, we could have many, many different ways to improve fruit quality.”
