Researchers decoded the kiwifruit genome and found it has similarities between its 39,040 genes. It also has common features with plant other species such as potatoes and tomatoes.
"The kiwifruit is an economically and nutritionally important fruit crop. It has long been called 'the king of fruits' because of its remarkably high vitamin C content and balanced nutritional composition of minerals, dietary fiber and other health-benefits," Zhangjun Fei, a scientist from the Boyce Thompson Institute at Cornell University, said in a Cornell news release.
"The genome sequence will serve as a valuable resource for kiwifruit research and may facilitate the breeding program for improved fruit quality and disease resistance," Fei said.
The kiwifruit did not become a commercial crop until it was discovered by New Zealanders in the 20th century. It grows on "woody vines" similar to grapes' and belongs to the Ericales order which also encompasses blueberries and Brazil nuts.
The research team was surprised to find a number of similarities within the kiwi's own DNA. They found evidence of two "unusual mishaps" that occurred during cell division as far back as 80 million years ago, when an "extensive expansion of genes arose from an entire extra copy of the genome, followed by extensive gene loss," the news release reported.
"The kiwifruit genome has undergone two recent whole-genome duplication events," Fei said.
The team found that when the genes were duplicated they were able to mutate and perform entirely new functions within the organisms. The process, called neofunctionalization, did not cause any harm to the fruit.
"The duplication contributed to adding additional members of gene families that are involved in regulating important kiwifruit characteristics, such as fruit vitamin C, flavonoid and carotenoid metabolism," Fei said.
The team compared the genomes of a Chinese kiwi variety called "Hongyang," with other plant species such as "tomato, rice, grape and the mustard weed Arabidopsis." They found at least 8,000 common genes among the five species.
The discovery showed "important evolutionary relationships," including how genes developed in traits like ripening, resistance to disease, and metabolism.
"The kiwifruit genome sequence represents the first of a member in the order Ericales, thus providing a valuable resource for comparative genomics and evolutionary studies," Fei said. "We expect to continue generating genome sequences from other kiwifruit varieties to investigate the genetic diversity of kiwifruit and elucidate regulatory networks of important biological processes."
This study marks the first time the kiwifruit's genome was sequenced in terms of "breeding and improvement."
