Scientists in Uganda have started confined trials of a
genetically modified strain of banana that is expected to be resistant to the
banana-root nematode (Radopholus similis).
The
banana root-pest causes a lesion on the plant’s root, which results in the
plant suffering malnutrition, leading to heavy crop losses.
Principal
investigator Charles Changa said the banana plants, under confined trials at
the National Agricultural Research Laboratories, Kawanda, have been modified
with either single or multiple anti-nematode genes derived from maize, rice,
papaya, and Irish potatoes to confer more than 80 per cent resistance to
nematode infestation.
“There
are three versions of Cysteine proteinase inhibitors (cystatins) that were
derived from maize, rice and papaya sources. The other antinematode gene, the
aspartic protease inhibitor, was derived from Irish potato,” said Dr Changa.
Dr
Changa said the banana plants were modified with the antinematode genes, which
would result in the nematodes being unable to digest protein from the banana
plant roots, hence slowing down their growth and rapid multiplication.
Dr
Changa added that some of the banana plants were modified with an antinematode
peptide — a short form of a protein that is produced in the banana plant root
to prevent nematodes from actually finding and colonising their roots for
feeding.
The
trials become the latest on genetically modified (GM) bananas in Uganda aimed
at restoring the crop, which is currently threatened by pests and diseases
throughout the country.
Uganda
carried out confined field trials on banana to test black sigatoka disease
resistance (2007-2009), and two ongoing trials to test banana bio-fortified
with vitamin A and iron and testing resistance to banana bacterial wilt.
Nematodes
are small parasitic worms that are only visible with the aid of a microscope.
Although there are different types of banana nematodes, burrowing nematode
(Radopholus similis) is the most widespread and destructive banana nematode in
Uganda’s central region, causing up to 50 per cent yield losses, scientists
say.
These
worms invade and damage banana root systems by causing root lesions and in
extreme cases root rotting thereby affecting water and nutrient uptake from the
soil. The rotten roots become too weak to give adequate support to banana
plants.
Scientists
say the nematode pest has been the main reason for the reduction in the
lifespan of banana plantations in the central region of the country. The life
span of banana plantations has reduced to less than five years compared with 50
years in the western part of the country.
Arthur
Tugume, a lecturer at the Department of Biological Sciences at Makerere
University, told The EastAfrican that the new technology has no effect on the
crop or on human beings.
“It
is fine for the crop to use genes from different plants… that is how the crop
protects itself naturally. However, adequate evaluations need to be carried out
to see how the crop responds,” said Dr Tugume.
Dr
Changa said the GM banana varieties will be evaluated in similar field trials
across the country to determine their effectiveness in multiple agro-ecological
zones and the stability of the antinematode gene.
Genetically
modified law
If
the nematode-resistant banana proves successful in the field trials, Ugandan
farmers will only have access to the planting materials after the GM law is in
place and all safety measures have been addressed. Uganda plans to
commercialise its first GM banana by 2017.
The National Biotechnology
and Biosafety Bill, 2012, which among other roles provides a regulatory
framework to facilitate safe development and application of biotechnology, is
currently at the committee stage in parliament.
The National Agricultural
Research Laboratories is carrying out the research in collaboration with
international scientists from the International Institute of Tropical
Agriculture (IITA), Cornell University, USA, and the University of Leeds, UK.
Uganda’s population depends
on banana mainly for local consumption, with an estimated per capital
consumption of over 300kg, the highest rate in the world, according to National
Crop Resources Research Institute.
Story published on May 4, 2013 in The EastAfrican
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