References

Abramovitch, R.B., Kim, YJ., Chen, S., Dickman, M.B. and Martin, G.B. (2003) Pseudomonas type III effector AvrPtoB induces plant disease susceptibility by inhibition of host programmed cell death. The EMBO Journal 22, 60-69.

Beers, E.P. and McDowell, J.M. (2001) Regulation and execution of programmed cell death in response to pathogens, stress and developmental cues. Current Opinion in Plant Biology 4, 561-567.

Coffeen, W.C. and Wolpert, TJ. (2004) Purification and characterization of serine proteases that exhibit caspase-like activity and are associated with programmed cell death in Avena sativa. The Plant Cell 16, 857-873.

Das, G. and Sen-Mandi, S. (1992) Triphenyltetrazolium chloride staining pattern of differentially aged wheat seed embryos. Seed Science and Technology 20, 367-373.

Eason, J.R., Ryan, DJ., Pinkney, T.T. and O'Donoghue, E.M. (2002) Programmed cell death during flower senescence: isolation and characterization of cysteine proteinases from Sandersonia aurantiaca. Functional Plant Biology 29, 1055-1064.

Fath, A., Bethke, P., Beligni, V. and Jones, R. (2002) Active oxygen and cell death in cereal aleurone cells. Journal of Experimental Botany 53, 1273-1282.

Fu, J.R., Lu, X.H., Chen, R.Z., Zhang, B.Z., Liu, Z.S., Ki, Z.S. and Cai, C.Y. (1988) Osmocon-ditioning of peanut (Arachis hypogaea L.) seeds with PEG to improve vigor and some biochemical activities. Seed Science and Technology 16, 197-212.

Fukuda, H. (2000) Programmed cell death of tracheary elements as a paradigm in plants. Plant Molecular Biology 44, 245-253.

Groover, A. and Jones, A.M. (1999) Tracheary element differentiation uses a novel mechanism coordinating programmed cell death and secondary cell wall synthesis. Plant Physiology 119, 375-384.

Gunawardena, A.H.L.A.N., Greenwood, J.S. and Dengler, N.G. (2004) Programmed cell death remodels lace plant leaf shape during development. The Plant Cell 16, 60-73.

Hengartner, M.O. (2000) The biochemistry of apoptosis. Nature 407, 770-776.

Kim, M., Ahn, J.W., Jin, U.H., Chai, D., Poek, K.H. and Pai, H.S. (2003) Activation of the programmed cell death pathway by inhibition of proteasome function in plant. Journal of Biological Chemistry 278, 19406-19415.

Krüger, J., Thomas, C.M., Golstein, C., Dixon, M.S., Smoker, M., Tang, S., Mulder, L., and Jones, J.D.G. (2002) A tomato cysteine protease required for Cf-2-dependent disease resistance and suppression of autonecrosis. Science 296, 744-747.

Kuo, A., Cappelluti, S., Cervantes-Cervantes, M., Rodriguez, M. and Bush, D.S. (1996) Okadaic acid, a protein phosphatase inhibitor, blocks calcium changes, gene expression and cell death induced by gibberellin in wheat aleurone cells. The Plant Cell 8, 259-269.

Levine, A., Tenhaken, R., Alvarez, M., Palmer, R. and Lam, CJ. (1994) H2O2 from the oxidative burst orchestrates the plant hypersensitive disease resistance response. Cell 79, 583-593.

Mackey, D., Holt, B.F. III, Wiig, A. and Dangl, J.L. (2002) RIN4 interacts with pseudomonas syringae type III effector molecules and is required for RPM1-mediated resistance in Arabidopsis. Cell 108, 743-754.

McDonald, M.B. (1999) Seed deterioration: physiology, repair and assessment. Seed Science and Technology 27, 177-237.

Pennell, R.I. and Lamb, C. (1997) Programmed cell death in plants. The Plant Cell 9, 1157-1168.

Priestley, D.A. (1986) Seed Aging. Comstock Publishing Associates, Ithaca, New York.

Rao, M.V. and Davis, K.R. (2001) The physiology of ozone induced cell death. Planta 213, 682-690.

Schmid, M., Simpson, D., Sarioglu, H., Lottspeich, F. and Gietl, C. (2001) The ricinosomes of senesc-ing plant tissue bud from the endoplasmic reticulum. Proceedings of the National Academy of Sciences of the United States of America 98 (9), 5353-5358.

Solomon, M., Belenghi, B., Delledonne, M., Menachem, E. and Levine, A. (1999) The involvement of cysteine proteases and protease inhibitor genes in the regulation of programmed cell death in plants. The Plant Cell 11, 431-443.

Song, S.Q., Fu, J.R. and Xia, W. (1992) Studies on accelerated aging and peroxidation of membrane lipids in peanut (Arachis hypogaea L.) seeds. Oil Crops of China 3, 31-33.

Song, S.Q., Fredlund, K.M. and Möller, I.M. (2001) Changes in low molecular weigh heat shock protein 22 of mitochondria during high temperature accelerated ageing of Beta vulgaris L. seeds. Acta Phytophysiology Sinica 27, 73-80.

Vaux, D.L. and Korsmeyer, S.J. (1999) Cell death in development. Cell 96, 245-254.

Wan, L., Xia, Q., Qiu, X. and Selvaraj, G. (2002) Early stages of seed development in Brassica napus: a seed coat-specific cysteine proteinase associated with programmed cell death of the inner integument. The Plant Journal 30, 1-10.

Wang, M., Oppedijk, B.J., Lu, X., Duijin, B.A. and Schilperoort, R.A. (1996) Apoptosis in barley aleu-rone during germination and its inhibition by abscisic acid. Plant Molecular Biology 32, 1125-1134.

Wu, H.M. and Cheun, A.Y. (2000) Programmed cell death in plant reproduction. Plant Molecular Biology 44, 267-281.

Young, T.E. and Gallie, D.R. (2000) Programmed cell death during endosperm development. Plant Molecular Biology 44, 283-301.

Storage and Germination Response of Recalcitrant Seeds Subjected to Mild Dehydration

S. Eggers, D. Erdey, N.W. Pammenterand P. Berjak

School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban 4041, South Africa

A problem associated with the storage of fully hydrated recalcitrant seeds is germination in storage, and it has been suggested that this problem could be overcome by partial dehydration, which is sufficient to prevent germination but high enough to avoid desiccation damage (i.e. 'sub-imbibed' storage). However, partial drying (pd) is shown to stimulate germination, and this process could reduce storage lifespan. Data are presented on recalcitrant seeds from a number of species, demonstrating the enhancement of germination by rapid mild dehydration, and the adverse effects of this mild dehydration on subsequent storage at a range of temperatures.

Recalcitrant seeds, by definition, are desiccation-sensitive and hence cannot be stored by the conventional methods employed for orthodox seeds. Not only does this make the long-term conservation of their genetic resources difficult, but it also places limitations on normal seed-handling procedures. To date the only 'successful' way of storing recalcitrant seeds is in the hydrated condition, at their shedding water content, but storage lifespan varies from several months, at best, to a week or two, depending on the species and the physiological condition of the seeds (King and Roberts, 1980). There are two main problems that are associated with hydrated storage: (i) seeds will often germinate in storage (King and Roberts, 1980); and (ii) the effects of fungal contamination can be severe, as the conditions (i.e. high humidity and temperature) necessary for hydrated storage also favour fungal proliferation (Mycock and Berjak, 1990).

Recalcitrant seeds are metabolically active (Berjak et al., 1984; Farrant et al., 1997), undergo continued development after shedding that grades into germination-associated

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