Analysis of Brz effects onto monocot rice (Nipponbare)

Abstract

Brassinosteroids occurs both in dicot and monocot. Brassinosteroid-deficient mutants of dicot and monocot showed dwarfism, and major brassinosteroid biosynthesis genes and a receptor BRI1 are evolutionary conserved between dicot and monocot.
When seeds of rice wild type (Nipponbare) were germinated in the deep 1/2MS liquid medium under dark condition, the first leaf coleoptile elongated to the surface of the liquid medium. The rice coleoptiles grown in the medium including Brz showed dwarf phenotype. This dwarfism induced by Brz tratment was recovered by brassinosteroid treatment. In the dwarf coleoptile of Brz- treated rice, choloroplastic genes that are not expressed in the rice grown in the normal 1/2MS medium were expressed. These results suggested that Brz caused the de-etiolation in the dark to not only dicot but also monocot.