This collection of papers has been brought together to acknowledge the invaluable contribution of Wouter G. van Doorn (13 December 1951–16 May 2015) to plant science and the broader scientific community. Wouter was an admirable and passionate scientist who lived by the maxim ‘I have striven not to laugh at human actions, not to weep at them, nor to hate them, but to understand them’ (Baruch Spinoza). It was his PhD dissertation at the University of Utrecht entitled ‘Vascular occlusion in stems of cut rose flowers’ that opened up a whole area of experimental work aimed at understanding flower senescence and other programmed cell-death processes in plants. Wouter van Doorn’s legacy is not simply limited to his excellent series of high impact articles in basic and applied science (though these are impressive in themselves) but reaches out through the students and scientists with whom he came into contact.

Van Doorn’s legacy

The unique combination of interconnected knowledge generation and transfer, basic and applied science, and student training was one of the hallmarks of Van Doorn’s work. His contribution to science was based not only on establishing new concepts and findings on flower senescence and other programmed cell death processes in plants, but also on his way of understanding science and life, helping others to advance on their own.

 

Programmed cell death (PCD) has received particular attention in plants because it is at the centre of a number of physiological processes, from germination to whole-plant senescence (especially in monocarpic plants, such as Arabidopsis), passing by other essential processes along the way, such as xylem differentiation and aerenchyma formation ( Van Hautegem et al. , 2015 ). Another of these physiological processes is flower senescence, particularly the senescence of petals. Pollination usually triggers petal senescence, although the petals of some flowers also senesce in its absence. Petal senescence, as with leaf senescence (although to a lesser extent), leads to the remobilization of nutrients, which in the case of petals are transferred to the ovary for fertilization and fruit growth ( Jones, 2013 ; Rogers and Munné-Bosch, 2016 ). Petal senescence is an irreversible, strictly developmentally regulated process, in which PCD plays a major role. Van Doorn and colleagues led this topic during the past decade, helping to establish a clear classification of PCD in plants ( Van Doorn and Woltering, 2004 , 2005 , 2008 , 2010 ; Van Doorn, 2011 ; Van Doorn et al. , 2011 ). In this respect, Van Doorn and Woltering (2010) argue that ‘we need not necessarily adhere to the definitions as currently in use in animal science’ and ‘to move forward in this field we need a better understanding of the genesis of autophagosome-like structures in plants … with detailed electron microscope data on the vesicles involved.’

This special issue builds on our current knowledge of PCD in plants, including reviews and new research on petal senescence. Shibuya et al. (2016) cover recent findings on the morphology of senescing petal cells and the regulatory mechanisms of PCD by transcription factors. Mira et al. (2016) discuss how phytoglobins (previously termed non-symbiotic hemoglobins, well-known nitric oxide scavengers) modulate cellular responses to auxin, cytokinin and jasmonic acid during growth and development, as well as in stress responses. Latrasse et al. (2016) focus their review on chromatin condensation and histone modifications associated with a major transcriptional switch occurring during PCD in response to various stimuli. Finally, Trivellini et al. (2016) elegantly describe the spatial and temporal dynamics of transcriptome changes during flower opening and senescence in the hibiscus flower. It is my hope that this set of papers will provide an improved understanding of petal senescence and other PCD processes in plants, helping stimulate new avenues of research in the area.

To the memory of Wouter van Doorn: your legacy will continue in our seminars with undergraduate and graduate students .

References

Jones
ML
.
2013
.
Mineral nutrient remobilization during corolla senescence in ethylene-sensitive and -insensitive flowers
.
AoB Plants
 
5
, plt023.
Latrasse
D
Benhammed
M
Bergounioux
C
Raynaud
C
Delarue
M.
2016
.
Plant programmed cell death from a chromatin point of view
.
Journal of Experimental Botany
 
67
,
5887
5900
.
Mira
M
Hill
RD
Stasolla
C.
2016
.
Regulation of programmed cell death by phytoglobins
.
Journal of Experimental Botany
 
67
,
5901
5908
.
Rogers
HJ
Munné-Bosch
S.
2016
.
Production and scavenging of reactive oxygen species and redox signaling during leaf and flower senescence: similar but different
.
Plant Physiology
 
171
,
1560
1568
.
Shibuya
K
Yamada
T
Ichimura
K.
2016
.
Morphological changes in senescing petal cells and the regulatory mechanism of petal senescence
.
Journal of Experimental Botany
 
67
,
5909
5918
.
Trivellini
A
Cocetta
G
Hunter
DA
Vernier
P
Ferrante
A.
2016
.
Spatial and temporal transcriptome changes occurring during flower opening and senescence of the ephemeral hibiscus flower, Hibiscus rosa-sinensis
.
Journal of Experimental Botany
 
67
,
5919
5931
.
van Doorn
WG
.
2011
.
Classes of programmed cell death in plants, compared to those in animals
.
Journal of Experimental Botany
 
62
,
4749
4761
.
van Doorn
WG
Beers
EP
Dangl
J
et al
.
2011
.
Morphological classification of plant cell deaths
.
Cell Death and Differentiation
 
18
,
1241
1246
.
van Doorn
WG
Woltering
E.
2004
.
Senescence and programmed cell death: substance or semantics?
Journal of Experimental Botany
 
55
,
2147
2153
.
van Doorn
WG
Woltering
E.
2005
.
Many ways to exit? Cell death categories in plants
.
Trends in Plant Science
 
10
,
117
122
.
van Doorn
WG
Woltering
E.
2008
.
Physiology and molecular biology of petal senescence
.
Journal of Experimental Botany
 
59
,
453
480
.
van Doorn
WG
Woltering
E.
2010
.
What about the role of autophagy in PCD?
Trends in Plant Science
 
15
,
361
362
.
van Hautegem
T
Waters
AJ
Goodrich
J
Nowack
MK
.
2015
.
Only in dying, life: programmed cell death during plant development
.
Trends in Plant Science
 
20
,
102
113
.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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