快猫短视频

Sydney

THE writing may be on the wall for oranges with pips. Biologists in
Australia and Japan have genetically engineered tobacco plants so that they
destroy their own seeds. They say the same technique should work in citrus
crops.

Anna Koltunow of the Division of Horticulture of the CSIRO, Australia鈥檚
national research agency, in Adelaide, and Fumio Takaiwa of Japan鈥檚 National
Institute of Agrobiological Resources in Tsukuba, linked a gene that kills cells
with a 鈥減romoter鈥� DNA sequence that switches on a gene active during seed
formation. The gene chimera delivers a deathblow to developing seeds.

鈥淚t looks promising from the results we鈥檝e got in tobacco,鈥� Koltunow told
快猫短视频. 鈥淎ll of the seeds in the plant stop developing. All that
is left is a small, soft seed trace.鈥�

The researchers call their gene SDLS-2. The cell-killing component
is found in a wide range of plants, and kills unwanted cells during plant
development. Koltunow and Takaiwa have been trying to link the gene to promoters
that would make it destroy seeds since 1992. The first version killed seeds, but
did not obliterate them. Another problem was ensuring that the promoter did not
switch on the gene too early, which in citrus crops could prevent fruit forming,
or cause it to fall off the tree before it is full grown.

Koltunow and Takaiwa are now inserting SDLS-2 into citrus plants, and
are positive about the chances of success. The trees take up to five years to
flower for the first time. But in the meantime, the researchers hope to get some
early indications from tests on the short-lived weed Arabidopsis
thaliana, the seeds of which develop in much the same way as citrus
seeds.