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Titre du document / Document title

Contractile roots in succulent monocots : convergence, divergence and adaptation to limited rainfall

Auteur(s) / Author(s)

NORTH Gretchen B. (1) ; BRINTON Erin K. (1) ; GARRETT Tadao Y. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Biology, Occidental College, Los Angeles, CA 90041, ETATS-UNIS

Résumé / Abstract

Contractile roots (CRs) that pull shoots further down in the soil are a possible example of convergent evolution in two monocot families, the Agavaceae and the Asphodelaceae. The association between CRs, water uptake and habitat aridity was investigated for agaves, yuccas and aloes by assessing the occurrence of CRs and the amount of root contraction for glasshouse-grown plants with respect to mean annual rainfall of their native habitats. Structural features of CRs as well as root hydraulic conductance were compared with those of non-contractile roots (NCRs). CRs occurred in 55% of the 73 species examined, including 64% of the agaves and 85% of the yuccas, but in none of the aloes despite the occurrence of CRs in related genera. The phylogenetic distribution of CRs was consistent with multiple acquisitions or losses of the trait. The amount of root contraction showed a highly significant negative relationship with mean annual rainfall, although other environmental factors may also be important. Radial hydraulic conductance of the basal (contractile) zone exceeded that of the midroot zone for CRs; for NCRs, the opposite was true. Thus, CRs in the species examined may provide a mechanism for greater water uptake near the soil surface in regions with limited rainfall.

Revue / Journal Title

Plant, cell and environment    ISSN  0140-7791   CODEN PLCEDV 

Source / Source

2008, vol. 31, no8, pp. 1179-1189 [11 page(s) (article)] (3/4 p.)

Langue / Language

Anglais

Editeur / Publisher

Blackwell, Oxford, ROYAUME-UNI  (1978) (Revue)

Mots-clés anglais / English Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Agavaceae

;

Yucca

;

Agave

;

Drought

;

Adaptation

;

Root

;

Mots-clés français / French Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Agavaceae

;

Yucca

;

Agave

;

Sécheresse

;

Adaptation

;

Racine

;

Mots-clés espagnols / Spanish Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Agavaceae

;

Yucca

;

Agave

;

Sequedad

;

Adaptación

;

Raíz

;

Mots-clés d'auteur / Author Keywords

Agave

;

Aloe

;

Yucca

;

convergent evolution

;

drought adaptation

;

hydraulic conductance

;

root anatomy

;

water uptake

;

Localisation / Location

INIST-CNRS, Cote INIST : 17987, 35400019604165.0120

Nº notice refdoc (ud4) : 20505724



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