Genetic Analysis of the Sheathed Panicle Trait in Rice

Gamadi rice variety shows complete sheathed panicle which remains enclosed within its flag leaf sheath until maturity. The main panicles of F1 plants, which were crossed with normal panicle-exserting type showed most of portion of the panicle exerted but never 100% exerted and side tillers showed mostly in complete to partial exsertion. We classified F2 population into five different types of panicle exsertion namely, 1)Complete panicle enclosed type 2)Panicle tip exsertion type 3)Panicle partly exserted type (40-60% portion of the panicle exserted) 4)Panicle nearly completely exserted type, but never 100%(F1type) and 5)Panicle completely exserted type(normaltype). Genetic analysis and allelism test showed the panicle enclosing character was controlled by two complementary dominant genes with the segregation ratio of 9 incomplete to 7 normal panicle exserting types. These genes, thus designated as G-a, G-b. G-a (Shp-3) and G-b (Shp-4), were found to be linked with the nl(Chr.5) and bc(Chr.3) genes, respectively. This work was supported by a grant from the Next Generation BioGreen 21 Program (Plant Molecular Breeding Center, No.PJ009076), Rural Development Administration, Republic of Korea.