Amino acid transporters (AATs) play roles in nutrient allocation during
plant development. Kai Lu of Wuhan Institute of Bioengineering in China
demonstrated that inhibiting the expression of the rice amino acid
transporter OsAAP3 can boost grain yield through increasing the number of
tillers.

Elevated expression of OsAAP3 in transgenic plants resulted in significantly
higher amino acid concentrations and inhibited bud outgrowth and rice
tillering. However, knockout of OsAAP3 decreased the amino acid
concentrations to a small extent, and thus promoted bud outgrowth,
increasing significantly tiller numbers. This led to an enhanced grain yield
and nitrogen use efficiency.

The team also found that the expression of OsAAP3 was higher in Japonica,
which produced fewer tillers than Indica. The team then generated
knockout-lines of OsAAP3 on Japonica using CRISPR-Cas9, resulting in
Japonica mutant lines with enhanced grain yield.

These results suggest that manipulation of OsAAP3 expression could be used
to increase grain yield in rice.

[onlinelibrary.wiley.com]