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Scientists uncover plants’ vitamin C secret |
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Agricultural scientists have uncovered the last big secret of
vitamin C in plants. The breakthrough in understanding just
how plants manufacture vitamin C will enable Hortresearch, New
Zealand, to identify DNA markers for individual plants that
naturally produce high levels of the vitamin. These plants are
likely to be used in selective breeding programmes to produce
fruits with more vitamin C in a form easily retained by the
body, unlike large doses taken in vitamin pills.
Hortresearch’s General Manager (Science), Dr. Bruce Campbell,
said his team has isolated the last undiscovered enzyme and
proved that it controlled vitamin C in plants. The scientists
studied kiwifruit, a plant naturally high in vitamin C, with
typical green kiwifruit – bred from Actinidia deliciosa –
containing about 100 mg in each 100 g of fruit. They also
worked on an inedible wild kiwifruit variety called Actinidia
eriantha – with a white, hairy skin, which is easy to peel –
because it contains a massive 800 mg of vitamin C per 100 g.
Source:
www.archives.foodsafety.ksu.edu |
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Sorghum may benefit from cloned toxicity-tolerant
gene |
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When soils are too acidic, the aluminium that is locked up in
clay minerals dissolves into the soil as toxic ions, making it
hard for most plants to grow. Aluminium toxicity in acidic
soils limits crop production in as much as half the world’s
arable land, mostly in developing countries in Africa, Asia
and South America. Now, researchers at Cornell University, the
United States, have cloned a new aluminium-tolerant gene in
sorghum and expect to have novel genetically engineered
aluminium-tolerant sorghum lines by next year. Sorghum is an
important food crop in Africa, Central America and South Asia
and is the world’s fifth most important cereal crop.
Research by Dr. Leon Kochian – a Cornell adjunct professor of
plant biology and director of the Plant, Soil and Nutrition
Laboratory of the United States Department of Agriculture
Agriculture Research Service (USDA-ARS) – and colleagues
showed that in aluminium-tolerant sorghum varieties, special
proteins in the root tip release citric acid into the soil in
response to aluminium exposure. Citric acid binds aluminium
ions very effectively, preventing the toxic metal from
entering the roots.
The researchers used genetic mapping to identify a single gene
that encodes a novel membrane-transporter protein responsible
for the citric acid release. They discovered that the gene is
only turned on to express the protein and transport citric
acid when aluminium ions are present in the surrounding soil.
The researchers have now used the sorghum gene to engineer
aluminium-tolerant transgenic Arabidopsis thaliana and wheat
plants. The map-based cloning of this agronomically important
gene in sorghum is helping advance this species as a model for
further exploring the aluminium tolerance mechanisms and
discovering new molecular genetic solutions to improving crop
yields, Dr. Kochian said.
Source:
www.news.cornell.edu |
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Genetically modified eucalyptus as carbon sink |
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Eucalyptus trees genetically modified by a team of biologists
from Taiwan and the United States have proven capable of
ingesting up to three times more carbon dioxide (CO2) than
normal strains, indicating a new path to reducing greenhouse
gases and global warming. The scientists from the Taiwan
Forestry Research Institute (TFRI) and North Carolina State
University in the United States carried out the gene
modification project that not only creates eucalyptus with a
higher than normal CO2 absorptive capacity, but also causes
them to produce less lignin and more cellulose.
TFRI researcher Dr. Chen Zenn-zong explained that cellulose,
hemicellulose and lignin in trees are all created from carbon
elements. “However, only cellulose can be used in commercial
processes of pulp manufacture and bio-ethanol extraction,” he
added. The project therefore aims to increase the value of
genetically modified eucalyptus to related industries by
adjusting the ratio of lignin and cellulose. “Meanwhile, we
enhance the tree’s capacity in absorbing CO2 to reduce
greenhouse gases, so that more trees planted for production,
the more CO2 are consumed,” said Dr. Chen. With every
eucalyptus carrying 18 per cent less lignin and 4.5 per cent
more cellulose, he estimates that a pulp factory with an
annual output of 1 million tonnes could generate extra revenue
of about US$36 million every year.
Source:
www.agbios.com |
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Discovery promises more nutritious cassava |
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Scientists from the International Centre for Tropical
Agriculture (CIAT), Colombia, have developed a new cassava
variety that might be more nutritious and easier to digest
than other varieties. Cassava is the staple food for millions
of poverty stricken people in Sub-Saharan Africa, South
America and parts of Asia. Cassava root is rich in
carbohydrates and starch, but low in protein and vitamins.
Compared with other starchy crops, cassava contains relatively
higher levels of amylose, which render it difficult to digest.
Dr. Hernan Ceballos and his colleagues from CIAT identified a
new cassava variety with significantly reduced amylose
content. Compared with traditional hard-to-digest cassava
varieties with 17-25 per cent amylose content, the mutant
contains an average of only 3.4 per cent amylose. The
scientists found no reduction in its starch content; therefore
it can provide more carbohydrates compared with traditional
varieties. This is the first report of a natural mutation in
cassava that resulted in drastic reduction of amylose content
in root starch. Besides being more nutritious and easily
digestible, the new variety may also be better suited for
bioethanol production.
Source:
www.isaaa.org |
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GM potatoes with better freezing tolerance |
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Potato, the fourth most important food crop, is a
frost-sensitive species incapable of cold acclimation. A brief
exposure to frost can significantly reduce yield, while hard
frosts can completely destroy entire crops. Improvement in its
freezing tolerance by just a few degrees would thus be of
considerable benefit. A group of researchers from Oregon State
University and Michigan State University in the United States,
and Kyung Hee University in Republic of Korea, has genetically
altered potato to be more tolerant to freezing.
Although genetic donors, particularly the cold-acclimatized
wild potatoes of South America, exist, transfer of freezing
tolerance to cultivated plants proved to be unsuccessful
because of the complex genetics of the trait and the
introduction of undesirable agronomic properties. By
introducing the AtBCF genes for freeze tolerance from
Arabidopsis with an activation control (promoter) only
for cold conditions, scientists successfully obtained several
potato lines with increased freezing tolerance of up to -5°C.
They also found out that the attachment of the
cold-inducible promoter minimize the expression of
agronomically undesirable traits, like delayed flowering and
retarded growth, previously attributed to the AtBCF genes.
Source:
www.isaaa.org |
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New flood-tolerant rice variety |
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The Philippine Rice Research Institute (PhilRice) has
developed a new rice variety tolerant to flood water and
resistant to the bacterial blast, stemborer and tungro, three
of the most dreaded rice pests.
The new variety, Tubigan 7, was developed using the DNA
marker-assisted selection (MAS) technique. It is the
first-ever successful DNA-MAS product developed in the
Philippines, and the second locally developed biotech rice,
after the tissue cultured variety of improved traditional
Wagwag grains. Tubigan 7 has a fertility restorer trait and
could yield about 8 tonnes per hectare during the dry season
cropping and 5-6 tonnes per hectare during the wet season, and
yields about 15 percent higher than the conventional harvest
record in the Philippines.
Dr. Antonio A. Alfonso, head of plant breeding and
biotechnology division of PhilRice, emphasized that Tubigan 7
is not a genetically modified crop, as the new variety was
obtained through conventional breeding. The country’s National
Seed Industry Council (NSIC) has officially released it as a
variety.
Source:
www.isaaa.org |
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New corn high in phytase |
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Chinese scientists have developed a genetically modified (GM)
corn that could help improve the nutritional value of
livestock feed and reduce pollution. The research work was
carried out by the Chinese Academy of Agricultural Sciences (CAAS),
and the corn has now entered pre-production field trials. The
GM corn produces seeds containing high levels of the phytase
enzyme, which helps livestock to digest phosphorus. Animals
lack phytase in their system. As a result, farmers have to add
the enzyme to animal feed to help livestock digest phosphorus.
The CAAS scientists isolated the gene that produces phytase
from the fungus Aspergillus, and inserted it into corn.
Initial tests have shown that the rate of seed germination,
growth speed and yield of the GM corn are no different as
compared with regular varieties. The scientists said that,
under current industry criteria for feed additives, adding
just a few grams of the GM corn seed per kilogram of animal
feed would satisfy livestock’s nutritional demand for
phosphorus. If the technology is commercialized, Chinese
farmers could save up to US$60 million per year in buying
industrial phytase.
Source:
www.agbioworld.com |
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Marker-free GM Soybean produces by gene excision |
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Selectable marker genes are used in plant transformation
systems to select transgenic events, but often the marker gene
is no longer needed after the transgenic plants are
regenerated. Their continued presence has always been the
focus of criticisms in genetic improvement of crops. A group
of researchers from DuPont recently produced transgenic
soybean lines, which are free from marker genes and tolerant
to glyphosate, through a self-activating gene excision system.
Unlike other approaches to produce marker-free plants, the
gene excision system employed by the researchers delivers
precise outcomes and does not require additional manipulations
of the transformation and regeneration process. The glyphosate
tolerance and marker genes were introduced along with a gene
coding for the enzyme Cre recombinase, which will remove
itself and the marker gene immediately upon induction. This
self-activating gene excision strategy is currently being
applied to numerous plants like maize, cotton and groundnut,
and many coniferous trees.
Source:
www.isaaa.org |
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