Chinese scientists from the Institute of Genetics and Developmental
Biology of the Chinese Academy of Sciences (CAS) have found a gene that
plays an important role in helping rice adapt to low soil nitrogen.
Nitrogen fertilizer application is a strategic challenge for sustainable
agriculture: On the one hand, it plays an indispensable role in
increasing crop yields, thus ensuring global food security. On the other
hand, it creates a severe threat to ecosystems. For this reason,
breeding new crop varieties with high nitrogen use efficiency (NUE) is a
high priority for both agricultural production and environmental protection.
Using a diversified rice population derived from different
ecogeographical regions, the scientists carefully evaluated how various
agronomic traits responded to nitrogen in fields with different nitrogen
supply conditions. They further performed a genome-wide association
study (GWAS). Surprisingly, only one very significant GWAS signal was
identified. The detail mechanisms how OsTCP19 works in regulating rice
tillering were also characterized.
More interestingly, by analyzing global soil nitrogen content data, the
researchers found a strong correlation between the allelic variation
of/OsTCP19/and global soil nitrogen-content distribution./OsTCP19/-H,
the high NUE allele, was highly preserved in rice types grown in
nitrogen-poor regions, but has been lost in rice types grown in
nitrogen-rich regions.
Notably,/OsTCP19/-H is also highly prevalent in wild rice--the ancestor
of modern cultivated rice--which was grown in natural soil without
artificial fertilizer input. As modern rice cultivars are mainly grown
with a bountiful nitrogen supply,/OsTCP19/-H has thus largely been lost.
Therefore, breeding high-yield crops with decreased nitrogen input can
be realized by bringing/OsTCP19/-H back to modern cultivars.
Indeed,/OsTCP19/-H introgression into modern cultivars can improve
nitrogen use efficiency 20-30% under conditions of decreased nitrogen
supply. For this reason, modern cultivated rice may be greatly improved
by bringing the lost allele back through the use of poor-soil landraces
that largely preserve the valuable genes of wild rice.
"This is truly groundbreaking. It will have implications not only for
the basic understanding of how plants/rice works, but also has enormous
implications for reducing fertilizer use," said Prof. Dale Sanders,
director of the John Innes Centre in the UK.
The findings represent an important breakthrough in plant nutrition
research and high NUE breeding and will greatly benefit sustainable
agriculture. The work not only offers novel insights about the genetic
basis for the geographic adaption of cultivated rice to soil fertility,
but also gives a hint about efficiently dissecting other complex traits.

Chinese Scientists Uncover Gene for Rice Adaption to Low Soil
Nitrogen----Chinese Academy of Sciences (cas.cn)
[english.cas.cn]