Relationship between plant stress tolerance, senescence and life span

Purpose of review: In many aerobic organisms, including fungi, yeasts, nematodes, fruit flies, mice and humans, it was found that increased resistance to stresses, especially oxidative stress, is correlated with extended longevity, which leads to the development of the "stress resistance" theory of aging. Nevertheless, very little is yet known regarding the accuracy of this theory in plants. Here we review recently accumulated evidence supporting the existence of tight correlation between stress tolerance and onset of senescence and determination of life span in plants, which supports the applicability of this theory to plants. Findings: Certain lines of evidence reveal the correlation between plant stress tolerance and regulation of senescence and life span. Firstly, it was found that the Arabidopsis delayed leaf senescence mutants ore1, ore3 and ore9 and the long-lived mutant gigantea exhibit enhanced tolerance to oxidative stresses. Secondly, transgenic cotton plants overexpressing the GF14λ regulator gene and Arabidopsis plants overexpressing the CBF2 transcriptional activator gene are more tolerant to drought and freeze stresses, respectively, and also show delayed leaf senescence phenotypes and enhanced life spans. Thirdly, Arabidopsis mutants deficient in vitamin C (vtc1) or vitamin E (vte2) are sensitive to oxidative stress, and exhibit premature senescence and reduced seed longevity, respectively. Together, these findings suggest a tight link between stress resistance and longevity in plants, similar to what has been hypothesised in animals. Direction for future research: Confirmation of the correlation between plant stress tolerance and regulation of senescence and life span opens the possibility of using this knowledge in future research and in breeding programs in order to develop new horticultural cultivars with enhanced tolerance to environmental stresses that will most likely include phenotypes with extended longevity and delayed senescence. Such cultivars will obviously have much improved postharvest storage lives and will suffer less from damage caused by accelerated senescence.