Functional analysis of ginseng GMADS2 Gene

Abstract

Ginseng has typical flowers which contain four concentrically arranged whorls of organs in the sequence five sepals (whorl 1), five petals (whorl 2), five stamens (whorl 3), and a carpel (whorl 4). Flower development of ginseng was investigated using scanning electron microscopy (SEM) and compared with that of in vitro flowers induced by benzyladenine (BA). The development of ginseng flowers was divided into stages based on morphological markers. The surface of the inflorescence meristem became widen and then first flower primordium arose from the periphery of the inflorescence meristem. At stage 1 pre-flower primordia arose. At stage 2 bract primordium and flower primordium were completely separated. As flower primordium developed its surface became flat and widen (stage 3). However, any sign of morphological differentiation of the floral organs was not found. At stage 4 first sepal primordium arose from the periphery of the flower primordium. A second sepal primordium then arose in a position that was nearly opposite to that of the first. The remaining three sepal primordia formed nearly together. At the same time with the arise of the later three sepal primordia five petal primordia were formed in a position alternate with the first whorl primordia (stage 5 and 6). The initiation of third whorl primordia laged behind second whorl primordia (stage 7). The filaments of the stamens remained relatively short during cellular differentiation of the anther, after which the filaments elongated. Following the initiation of the second and third whorl primordia, the remaining floral meristem gave rise to the fourth whorl, which arose as two distinct primordia. During this time the sepals had grown to enclose the inner floral organs (stage 8). Flowers induced in vitro were usually smaller than those in situ or atypical in shape. The carpel primordium of in vitro flower was formed very early (stage 4 or 5), resulting in flowers containing five sepal primordia and one car...