Rice Genetics IV - IRRI books - International Rice Research Institute

Molecular dissectionof cell death in riceH. Uchimiya, M. Kawai, M. Yamaguchi, and M. UmedaProgrammed cell death has been observed in various developmental processesin higher plants. The presence of air-filled spaces known as aerenchymain rice is considered to be an important anatomical adaptive featurenecessary for plant survival under flooded conditions. Ample evidence hasbeen presented to show that this system provides a diffusion path for thetransportation of oxygen from aerial plant parts to roots. In addition, themolecular dissection of cell death is discussed.Cyclin-dependent protein kinases (CDKs) are serine/threonine proteinkinases that are involved in the regulation of the eukaryotic cell cycle. Thegrowing list of CDKs in plant cells suggests that, during development, eachCDK may play a specific role at a specific time in the cell cycle. Rice plantsalso express different kinds of CDKs. We present the outcome of our workindicating that the division of rice cells might be regulated by different sets ofCDK/cyclin, leading to cell proliferation.The destination of plant cell life is under strict control with regard to adaptive featuresof biological mechanisms. Topics related to this control will be presented in terms ofcellular and molecular understanding of cell death and cell cycle regulation in riceplants.Cell death in rice: adaptive cellular pathwaysleading to water toleranceThe presence of gas-filled spaces, known as aerenchyma, in numerous plant speciesis considered to be an important anatomical adaptive feature necessary for survivalunder flooded conditions (Kawase 1981, Kawai and Uchimiya 2000). Ample evidencehas been presented to show that aerenchyma provide a diffusion path of lowresistance for the transport of oxygen from aerial plant parts to roots or rhizomes in awaterlogged, O 2 -deficient environment (Armstrong 1971). The formation of aerenchymais thought to occur by either lysigeny or schizogeny (Smirnoff and Crawford1983). Lysigenous gas spaces form via cell lysis, whereas schizogenous spaces formMolecular dissection of cell death in rice 365