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Conifer species adapt to low-rainfall climates by following one of two divergent pathways


Brodribb, TJ and McAdam, SAM and Jordan, GJ and Martins, SCV, Conifer species adapt to low-rainfall climates by following one of two divergent pathways, Proceedings of the National Academy of Sciences, 111, (40) pp. 14489-14493. ISSN 0027-8424 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 The Authors

DOI: doi:10.1073/pnas.1407930111


Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of lowlevels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates.

Item Details

Item Type:Refereed Article
Keywords:mortality, forest, stomata, conifers, ABA
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biological sciences
UTAS Author:Brodribb, TJ (Professor Tim Brodribb)
UTAS Author:McAdam, SAM (Dr Scott McAdam)
UTAS Author:Jordan, GJ (Professor Greg Jordan)
UTAS Author:Martins, SCV (Mr Samuel Martins)
ID Code:95873
Year Published:2014
Web of Science® Times Cited:196
Deposited By:Plant Science
Deposited On:2014-10-09
Last Modified:2017-11-01

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