DA1 and DAR1 are ubiquitin receptors that function as negative regulators of
cell proliferation during development in Arabidopsis. An arginine to lysine
mutant at amino acid site 358 could lead to the da1-1 phenotype, which
results in an increased organ size and larger seeds. The team led by
Guangning Xie from Shandong University in China separately introduced the
mutated ZmDA1 (Zmda1) and mutated ZmDAR1 (Zmdar1) into the maize elite
inbred line, DH4866.

The grain yield of the transgenic plants was 15% greater than that of the
wild types due to improvements in the grain number, weight, and starch
content. Analysis showed that overexpression of mutated Zmda1 and Zmdar1
promoted kernel development and enhanced expression of starch synthase
genes, leading to enhanced grain yield.

This study suggests that the overexpression of the mutated ZmDA1 or ZmDAR1
genes can improve starch synthesis in maize kernels. This could be a
candidate gene for improving maize yield.

[onlinelibrary.wiley.com]