Scientists decode kiwifruit genome

Scientists have decoded the DNA sequence of the kiwifruit and found that the fruit has many genetic similarities between its 39,040 genes and other plant species, including potatoes and tomatoes.
The study also unveiled two major evolutionary events that occurred millions of years ago in the kiwifruit genome.
"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 fibre and other health-benefits," said Zhangjun Fei, a scientist from the Boyce Thompson Institute at Cornell University.
Fei contributed to the study, which was conducted by a team of plant scientists from the US and China.

"The genome sequence will serve as a valuable resource for kiwifruit research and may facilitate the breeding programme for improved fruit quality and disease resistance," Fei said.
Scientists observed a high percentage of similarities within the kiwifruit DNA. The data revealed two unusual mishaps that occurred in the process of cell division about 27 and 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 kiwifruit genome has undergone two recent whole-genome duplication events," Fei said.
When genes are duplicated, the extra genes can mutate to perform entirely new functions that were not previously present in the organism.

This process, called neofunctionalisation, can occur with no adverse effects in plants and, in the case of kiwifruit, was quite beneficial.
"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," said Fei.
For the sequencing, the scientists used a Chinese variety called "Hongyang," which is widely grown in China, to produce the draft sequence.
They then compared kiwifruit to the genomes of other representative plant species including tomato, rice, grape and the mustard weed Arabidopsis. They uncovered about 8,000 genes that were common among all five species.

The comparison revealed important evolutionary relationships, including the development genes related to fruit growth, ripening, nutrient metabolism, and disease resistance.
The study was published in the journal Nature Communications.