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Front. Plant Sci. | doi: 10.3389/fpls.2019.01396

Desiccation-driven senescence in the resurrection plant Xerophyta schlechteri (Baker) N.L.Menezes: comparison of anatomical, ultrastructural and metabolic responses between senescent and non-senescent tissues.

Astrid L. Radermacher1, Stefanus F. du Toit1 and  Jill M. Farrant2*
  • 1University of Cape Town, South Africa
  • 2Molecular and Cell Biology, University of Cape Town, South Africa

Drought-induced senescence is a degenerative process that involves the degradation of cellular metabolites and photosynthetic pigments and uncontrolled dismantling of cellular membranes and organelles. Angiosperm resurrection plants display vegetative desiccation tolerance and avoid drought-induced senescence in most of their tissues. Developmentally older tissues, however, fail to recover during rehydration and ultimately senesce. Comparison of the desiccation-associated responses of older senescent tissues (ST) with non-senescent tissues (NST) will allow for understanding of mechanisms promoting senescence in the former and prevention of senescence in the latter.
In the monocotyledonous resurrection plant Xerophyta schlechteri (Baker) N.L.Menezes, leaf tips senesce following desiccation, whereas the rest of the leaf blade survives. We characterised structural and metabolic changes in ST and NST at varying water contents during desiccation and rehydration. Light and transmission electron microscopy was used to follow anatomical and subcellular responses, and metabolic differences were studied using gas chromatography-mass spectrometry and colorimetric metabolite assays. The results show that drying below 35% relative water content (0.7 gH2O/g dry mass) in ST resulted in the initiation of age-related senescence hallmarks and that these tissues continue this process after rehydration. We propose that an age-related desiccation sensitivity occurs in older tissues, in a process metabolically similar to that observed during age-related senescence in Arabidopsis thaliana.

Keywords: age-related snescence, desiccation tolerance, primary metabolism, senescence prevention, Xerophyta schlechteri, Age-related senescence, , desication tolerance, resurrection plant, Xerophyta viscosa, Xerophyta, Senescence (leaf), extremophyta

Received: 25 Jun 2019; Accepted: 09 Oct 2019.

Copyright: © 2019 Radermacher, du Toit and Farrant. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Jill M. Farrant, University of Cape Town, Molecular and Cell Biology, Cape Town, 7701, Western Province, South Africa,