The evolutionary basis of leaf senescence: Method to the madness?

Current Opinion in Plant Biology

Volumn 1, Issue 1, 1998, Pages 73-78

  Bleecker, Anthony B ^a  

^a UNIVERSITY OF WISCONSIN MADISON   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ANIMAL; CELL AGING; CELL DEATH; CYTOLOGY; EVOLUTION; GENE EXPRESSION REGULATION; GENETICS; PHYSIOLOGY; PLANT LEAF; REVIEW;

ANIMALS; CELL AGING; CELL DEATH; EVOLUTION; GENE EXPRESSION REGULATION, DEVELOPMENTAL; GENE EXPRESSION REGULATION, PLANT; PLANT LEAVES;

EID: 0031987782     PISSN: 13695266     EISSN: None     Source Type: Journal    
DOI: 10.1016/S1369-5266(98)80131-3     Document Type: Article

References (19)

1. Finch CE: Longevity, Senescence, and the Genome. Chicago: University of Chicago Press: 1990.
2. Noodén LD, Guiamet JJ: Genetic control of senescence and aging in plants. In Handbook of the Biology of Aging. Fourth edition. Edited by Schneider EL, Rowe JW. San Diego: Academic Press; 1996:94-118. The authors provide a summary of the field of plant senescence from several perspectives and include a survey of genes that are differentially expressed during senescence. They argue that, because leaves may senesce before or during reproduction, evolutionary models for animal senescence do not apply. This may seem true from a strictly whole-plant perspective, but not when one considers the individual leaf as a unit of selection.
3. Rose MR: Evolutionary Biology of Aging. Oxford: Oxford University Press; 1991.
4. Kirkwood TB, Rose MR: Evolution of senescence: late survival sacrificed for reproduction. Philos Trans R Soc Lond 1991, 332:15-24. The authors provide an interesting and readable discussion of two prominent theories that account for the evolution of senescence in animals: antagonistic pleiotropy and the disposable soma.
5. Roach DA: Evolutionary senescence in plants. Genetica 1993, 91:53-64.
6. Gan S, Amasino RM: Making sense of senescence. Plant Physiol 1997, 113:313-319. This recent review of leaf senescence both considers the recent studies on gene expression and summarizes the developmental and environmental pathways that influence the timing of senescence in different systems. The senescence syndrome is presented as a form of programmed cell death, but the authors do consider the apparent complexity of regulatory factors that may operate in the syndrome and suggest a network of parallel and overlapping pathways that control the process (Figure 3).
7. Buchanan-Wollaston V: The molecular biology of leaf senescence. J Exp Biol 1997, 307:181-199. The author focuses on the analysis of differential gene expression during leaf senescence. This is perhaps the most thorough of recent reviews on this topic. A flow chart of salvage pathways thought to be active during leaf senescence is provided and reconciled with the identities of many senescence-associated gene clones. An attempt is made to classify genes according to their expression patterns, of which 10 different classes are identified. It is recognized that the complexity of expression patterns may indicate a plethora of regulatory pathways. Yet, the author is convinced that transcriptional control is the key to senescence and that all genes which are differentially regulated must be important to the process.
8. Nam HG: The molecular genetic analysis of leaf senescence. Curr Opin Biotechnol 1997, 8:200-207. In the same vein as other recent reviews [7], the author use gene expression as the paradigm of control. An emphasis is placed here on the idea that hormonal and developmental pathways overlap in controlling different senescence-associated genes (SAGs) and that different forms of senescence (starvation induced, hormonally induced and age related) show differences in which SAGs are elevated. In the conclusion, the importance of considering post-transcriptional mechanisms for SAG abundance is emphasized. Examples where mRNA and protein abundance data do not necessarily agree are also noted as a cautionary point.
9. Wilson BJ: An evolutionary perspective on the 'death hormone' hypothesis in plants. Physiol Plant 1997, 99:511-516. The author considers the problem of how a developmental system that causes death could have evolved. Selection at several different levels is considered and the author concludes that nutrient competition between leaves and fruits is the best candidate. Wilson discounts this mechanism, however, because even old leaves are not net importers so their death is of no consequence; and also, monocarpic varieties do not show a consistent advantage over their polycarpic relatives in terms of yield. To the first argument, I would respond that export from older leaves, not competition for import, is the issue. Release of stored nitrogen and other nutrients from otherwise unproductive leaves is the trait under consideration. The second argument, therefore, is based on flawed experiments. Comparing varieties with multiple genetic differences in species that have been artificially selected by humans and grown under specialized protected conditions is not likely to be the criterion that evolutionary processes would use in selecting the trait.
10. Hensel LL, Grbic V, Baumgarten DA, Bleecker AB: Developmental and age related processes that influence the longevity and senescence of photosynthetic tissues in Arabidopsis. Plant Cell 1993, 5:553-564.
11. Weaver LM, Himelblau E and Amasino RM: Leaf senescence: gene expression and regulation. In Genetic Engineering, V.19: Principles and Methods. New York: Plenum; in press. This is a thorough review of leaf senescence that considers primarily the biochemical and molecular aspects of the process.
12. Lohman KN, Gan S, John MC, Amasino RM: Molecular analysis of natural leaf senescence in Arabidopsis thaliana. Physiol Plant 1994, 92:322-328.
13. Bleecker AB, Patterson SE: Last exit: senescence, abscission and meristem arrest in Arabidopsis. Plant Cell 1997, 9:1169-1179. This review focuses on Arabidopsis as a model system for the study of senescence and abscission. It includes considerations of somatic tissue senescence and the growth arrest of meristems that contribute to whole plant senescence. Theoretical discussions relevant to this paper are also included.
14. Gan S and Amasino RM: Inhibition of leaf senescence by autoregulated production of cytokinin. Science 1995, 270:1986-1988.
15. John I, Drake R, Farrell A, Cooper W, Lee P, Horton P, Grierson D: Delayed leaf senescence in ethylene deficient ACC-oxidase antisense tomato plants. Molecular and physiological aspects. Plant J 1995, 7:483-490.
16. Grbic V, Bleecker AB: Ethylene regulates the timing of leaf senescence in Arabidopsis. Plant J 1996, 8:595-602. The authors use ethylene insensitive mutants to investigate the role of ethylene in the timing of leaf senescence. Delayed leaf senescence was observed but when it did occur it was associated with wild-type levels of senescence-associated gene mRNAs. It was concluded that ethylene was neither necessary nor sufficient to cause leaf senescence, and that it only influenced the timing.
17. O'Neill S, Nadeau JA, Zhang XS, Bui AQ, Halevey AH: Interorgan regulation of ethylene biosynthetic genes by pollination. Plant Cell 1993, 5:419-432.
18. Thomas H, Smart CM: Crops that stay green. Ann Appl Biol 1993, 123:193-219.
19. Guiamet JJ, Giannibelli MV: Nuclear and cytoplasmic 'stay-green' mutations of soybean alter the loss of leaf soluble proteins during senescence. Physiol Plan 1996, 96:655-661.