A study published in Nature reports about a gene that improves plants'
ability to absorb nitrogen, which can help develop high-yielding varieties
of rice, wheat, and other staple crops that would need less fertilizer.

According to plant geneticist Xiangdong Fu from the Chinese Academy of
Sciences and co-authors, modern crops cannot absorb nitrogen as efficiently
as traditional crops can, thus fertilizers are applied to help modern crops
grow. However, when nitrogen-rich runoff from farm fields reaches rivers,
lakes and oceans, it can feed massive algal blooms that consume oxygen and
suffocate aquatic organisms. "That's why we need to look for new varieties
that can produce high yields, but with less fertilizer," Fu added.

Fu and colleagues studied the role of DELLA proteins that have been
pinpointed as the cause of modern crops' poor nitrogen absorption and short
stature. These proteins are disrupted by growth hormones in traditional
crops, while in modern plants, DELLA proteins thrive because of their
immunity to the hormones. Thus, the team searched for ways to combat DELLA
proteins. They scanned the DNA of 36 dwarf rice varieties and found two
genes that govern nitrogen consumption. One of the genes codes for DELLA,
and the other codes for growth-regulating factor 4 (GRF4), which has been
known to be involved only in grain size and yield. Fu and team further found
that GRF4 counteracts the effects of DELLA by influencing the plants to
absorb and metabolize nitrogen and carbon to support growth. Then they bred
rice plants to develop a better concentration of the GRF4 protein. This
leads to high yielding short plants which need less nitrogen than
conventional plants.

[www.nature.com]