Reference "A Loss-of-Function Mutation in the Rice KNOX Type Homeobox Gene, OSH3"

Reference ID

6711

Title

A Loss-of-Function Mutation in the Rice KNOX Type Homeobox Gene, OSH3

Source

Plant & cell physiology, 2002, vol. 43, pp. 44-51

Authors (3)

Sato-Y	Aoki-Y
Matsuoka-M

Abstract

KNOX homeodomain (HD) proteins encoded by KNOTTED1-like homeobox genes (KNOX
genes) are thought to work as switches for cells to change from an indeterminate
to a determinate state, although their direct functions are not clear. In the
process of isolating KNOX genes from rice, we found that one gene, named OSH3,
has two amino acid substitutions in three of the invariant amino acid residues
in the HD of KNOX proteins. These amino acid substitutions are not universal in
rice: two of the cultivars from the Indica variety of rice do not carry those
substitutions but two of the cultivars from Japonica variety do. We tested the
effect of these amino acid substitutions on their ability to form dimers and to
induce abnormal morophologies when overexpressed in transgenic plants. We found
that OSH3 without those substitutions can form dimers and can induce an abnormal
phenotype in overexpression studies, and that OSH3 with those amino acid
substitutions is defective in both. Based on these observations, we concluded
that OSH3 from two of the cultivars from the Japonica variety could have lost
its original function, or could have acquired a novel function by modifying the
action of HD, or both.