Rice Genetics IV - IRRI books - International Rice Research Institute

and, at 6 h, the population of S phase cells was at its peak with a threefold increase overuninduced plants. Between 6 h and 18 h of submergence, the number of cells in the Sphase leveled out to approximately twice the number found at 0 h. Therefore, the kineticpattern of Os;cycH;1 expression was similar to the kinetic pattern of S phase cells in themeristem. Moreover, in partially synchronized suspension cells of Os;cycH;1, transcriptswere abundant in the S phase. These data suggested that Os;cycH;1 expression wasinduced when cells entered the S phase at an elevated level and that CAK activity wasrequired for S phase progression.In plants, only little information is available about which cyclin binds to whichCDK to form an active kinase complex. Two Arabidopsis D-type cyclins, At;CycD1;1and At;CycD4;1, were capable of interacting with Cdc2aAt and Cdc2bAt in the yeasttwo-hybrid system (De Veylder et al 1997, 1999). Immunoprecipitates of tobaccoextract with anti-Nt;CycD3;1 antibody contained a protein that cross-reacted with theanti-PSTAIRE antibody, and that Cdc2Nt1-CycD3 complex was able to phosphorylateRb-related protein in vitro, whereas Cdc2Nt1 alone did not exhibit a phosphorylationactivity (Nakagami et al 1999). However, whether Nt;CycD3;1 specificallyactivates Cdc2Nt1 in tobacco remains to be determined. Therefore, rice cyclin H wouldbe the first plant cyclin whose specific partner has been identified (Yamaguchi et al2001).ReferencesArmstrong W. 1971. Radial oxygen losses from rice roots as affected by distance from theapex, respiration and water logging. Physiol. Plant 25:192-197.Armstrong J, Armstrong W. 1994. Chlorophyll development in mature lysigenous and schizogenousroot aerenchyma provides evidence of continuing cortical cell viability. New Phytol.126:493-497.Berg C, Willemsen V, Hage W, Weisbeek P, Scheres B. 1995. Cell fate in the Arabidopsis rootmeristem determined by directional signaling. Nature 378:62-65.Campbell R, Drew MC. 1983. Electron microscopy of gas space (aerenchyma) formation inadventitious roots of Zea mays L. subjected to oxygen shortage. Planta 157:350-357.Clark LH, Harris WH. 1981. Observation on the root anatomy of rice (Oryza sativa L.). Am. J.Bot. 68:154-161.Clarkson DT, Robards AW. 1975. The endodermis, its structural development and physiologicalrole. In: The development and function of roots. London (UK): Academic Press. p 415-436.Das DK, Jat RL. 1977. Influence of three soil water regimes on root porosity and growth offour rice varieties. Agron. J. 69:197-210.De Veylder L, Segers G, Glab N, Van Montagu M, Inzé D. 1997. Identification of proteinsinteracting with the Arabidopsis Cdc2aAt protein. J. Exp. Bot. 48:2113-2114.De Veylder L, Engler JA, Burssens S, Manevski A, Lescure B, Van Montagu M, Engler G, InzéD. 1999. A new D-type cyclin of Arabidopsis thaliana expressed during lateral root primordiaformation. Planta 208:453-462.Delong A, Calderon-Urrea A, Dellaporta SL. 1993. Sex determination gene TASSELSEED 2 ofmaize encodes a short-chain alcohol dehydrogenase required for stage-specific floral organabortion. Cell 74:757-768.Molecular dissection of cell death in rice 373