The GW2 gene is emerging as a key determinant of grain weight in cereal
crops. In hexaploid wheat (Triticum aestivum), it has three homoeologs,
TaGW2-A1, -B1, and -D1. The team of Yi Zhang from the Chinese Academy of
Sciences analyzed the CRISPR-edited mutants that lack one, two, or all three
homoeologs of TaGW2 to gain insights into the functions of TaGW2 in wheat
Both TaGW2-B1 and -D1 affect the thousand-grain weight (TGW) by influencing
grain width and length, but the effect conferred by TaGW2-B1 is stronger
than that of TaGW2-D1. There is also a functional interaction between the
TaGW2 homoeologs since the TGW increase shown by a double mutant (lacking B1
and D1) was substantially larger than that of their single mutants.
TaGW2-B1 and -D1 were also found to modulate cell number and length in the
outer pericarp of developing grains, with TaGW2-B1 being the more potent
one. TaGW2 homoeologs also affect grain protein content as this was
generally increased in all mutants, especially in the double and triple
mutants. Moreover, flour protein content and gluten strength were also
elevated in the mutants.
These data provide insights on the functions of the TaGW2 homoeologs in the
genetic control of grain weight and protein content traits in common wheat.
This may accelerate research on this important gene and its application in