April, 2007
Científicos
chinos desarrollan arroz de grano más grande
En un trabajo recientemente publicado en la revista Nature
Genetics, Lin Hongxuan y sus colegas de los Institutos para las
Ciencias Biológicas de Shanghai desarrollaron una variedad de
grano chino genéticamente modificada que produce granos más
largos y gruesos. Los resultados de pruebas preliminares
evidencian un aumento de 20% en el rendimiento.
Este avance es el resultado del análisis realizado sobre el
genoma del arroz el cual resultó en la identificación del gen
GW2 asociado con el tamaño del grano y el rendimiento.
La nueva variedad de arroz GM presenta unas propiedades de
cocción y calidad nutricional similar al arroz convencional,
aunque con un aspecto más oscuro. Aunque este resultado fue
tomado como un trabajo preliminar, Zhu Zhen, de la Academia de
Ciencias de China, señaló que este adelanto es importante y
añadió que “el descubrimiento de genes con importancia
agronómica es fundamental para el desarrollo de nuevas
variedades”.
Otro adelanto importante en este país, se está llevando a cabo
por parte de la compañía norteamericana de biotecnología,
Arcadia Biosciences, empresa que esta colaborando con la región
china de Ningxia Hui, la mayor productora de arroz del país, en
ensayos de variedades de arroz con mejor aprovechamiento de los
abonos, variedades que son capaces de mantener la productividad
con un aporte menor de fertilizante de base nitrogenada (Entre
50 – 60% menos)
Este tipo de arroz GM no solo supone un ahorro para los
agricultores, sino un menor impacto medioambiental al reducirse
la cantidad de nitrógeno que se pierde por escorrentía y causa
problemas de contaminación en las aguas, así como las emisiones
de gases de efecto invernadero de los campos de cultivo, en
particular oxido nitroso.
Source: Chinese Academy of Agricultural Sciences
 |
|
The grain size is significantly increased when GW2 is introduced into a small-grain rice variety. The scale is 3mm. |
CAS researchers have made
breakthrough progress in their genetic and gene functional
analysis of important agronomic traits. A research team led by
Prof. LIN Hongxuan from the Shanghai Institute of Plant
Physiology and Ecology (SIPPE), the CAS Shanghai Institutes for
Biological Sciences, is successful in cloning a gene underlying
quantitative trait locus (QTL), a region of DNA, that controls
grain weight and yield in rice. Their work has been reported
online by
Nature Genetics.
Many important agronomic traits in crop plants, including grain
weight -- one of the most important components of grain yield,
are complex traits controlled by QTLs, which are derived from
natural variations in crops. However, the molecular roles of
QTLs in the regulation of grain weight have not been fully
elucidated. After many years' hard work, Prof. Lin and
colleagues have obtained GW2, a new QTL that controls rice grain
width and weight.
They discovered that GW2 encodes a previously unknown RING-type
protein with E3 ubiquitin ligase activity, which is known to
function in the degradation by the ubiquitin-proteasome pathway.
Loss of GW2 function increases cell numbers, leading to a larger
(wider) spikelet hull, and it accelerates the grain milk filling
rate, resulting in enhanced grain width, weight and yield. Their
results suggest that GW2 negatively regulates cell division by
targeting its substrate(s) to proteasomes for regulated
proteolysis.
The functional characterization of GW2 provides insight into the
mechanism of seed development, according to experts. The feat,
which is hailed as a significant piece of wok in the history of
rice breeding for yield increase by a Nature Genetics reviewer,
is believed to be a potential tool for improving grain yield in
crops..
Lin and his group at the SIPPE-affiliated National Key
Laboratory of Plant Molecular Genetics have been working on
genetic and gene functional analysis of important agronomic
traits such as yield, cooking and tasting quality, and stress
tolerance or physiological tolerance, by using molecular marker
on high density rice genetic linkage map, sequence data of rice
genome, and genetic material constructed. Another of their
recent achievements is the cloning of SKC1, a salt-tolerant
functional gene of rice and making clear its biological
functions and mechanisms.
| Source:
Nature Genetics Link: http://www.nature.com/ng/journal/vaop/ncurrent/abs/ng2014.html
A QTL for rice
grain width and weight encodes a previously unknown
RING-type E3 ubiquitin ligase Grain weight is one of the most important components of grain yield and is controlled by quantitative trait loci (QTLs) derived from natural variations in crops. However, the molecular roles of QTLs in the regulation of grain weight have not been fully elucidated. Here, we report the cloning and characterization of GW2, a new QTL that controls rice grain width and weight. Our data show that GW2 encodes a previously unknown RING-type protein with E3 ubiquitin ligase activity, which is known to function in the degradation by the ubiquitin-proteasome pathway. Loss of GW2 function increased cell numbers, resulting in a larger (wider) spikelet hull, and it accelerated the grain milk filling rate, resulting in enhanced grain width, weight and yield. Our results suggest that GW2 negatively regulates cell division by targeting its substrate(s) to proteasomes for regulated proteolysis. The functional characterization of GW2 provides insight into the mechanism of seed development and is a potential tool for improving grain yield in crops. |
RELATED NEWS
Chinese scientists have found a gene which influences yield and grain size in rice
by Hepeng Jia,
SciDev.Net
April 11, 2007
Chinese scientists have identified and cloned a rice gene that influences rice grain weight and yield, which could help scientists develop higher yielding varieties of the world's most important food crop.
Little is known about the genetic mechanisms that determine yield and seed weight in plants, despite tremendous efforts by agricultural scientists in the past decade.
In a study published this week (8 April) in Nature Genetics, lead author Lin Hongxuan and colleagues from the Shanghai Institutes for Biological Sciences, studied two varieties of rice with highly significant differences in grain size.
After mapping their genomes, they found a gene called GW2 in the large-grain rice that was lacking in the small-grain rice.
They then created a variety of the naturally small-grained rice with the GW2 gene, and found that the gene increased the width and weight of rice grains and increased grain yield per plant by nearly 20 per cent.
The high-yield variant had nearly the same cooking or eating quality as conventional rice, although the grains had a darker appearance.
The team say the GW2 gene will facilitate breeding efforts to improve grain yield in food crops. But they say further evidence is needed to support their finding.
"The increased output of single plants might be influenced by environmental factors, so our finding needs to be tested in the randomised blocks of plants in paddies," Lin told SciDev.Net.
He said the GW2 gene might affect grain size by regulating the cell division cycle.
Zhu Zhen, deputy director of the Bureau of Life Sciences and Biotechnology of the Chinese Academy of Sciences, praised the study, saying it would give breeders more alternatives to explore in the search for improved varieties of rice.
"In the process of developing new crop varieties, the discovery of important agronomical genes is very important," Zhu told SciDev.Net.
Link to full paper
in Nature Genetics:
http://www.nature.com/ng/journal/vaop/ncurrent/full/ng2014.html
Reference: Nature Genetics doi: 10.1038/ng2014
(2007)
Other news from SciDev.Net