CONGRESO
LXV CONGRESSO NACIONAL DE BOTÂNICA
BOTÁNICA
XXXIV ERBOT - Encontro Regional de Botânicos MG, BA, ES 18 A 24 DE OUTUBRO DE 2014 - SALVADOR - BAHIA - BRASIL
Latinoamericano de
Botânica na América Latina: conhecimento, interação e difusão
PHENOTYPIC PLASTICITY AND ECOTYPIC
DIFFERENTIATION DRIVE DIFFERENT DROUGHT
RESISTANCE STRATEGIES IN THE DROUGHT-DECIDUOUS
PLANT ENCELIA CANESCENS (LAM., ASTERACEAE)
AUTOR(ES):Danny E. Carvajal;Andrea P. Loayza;Rodrigo S.
Rios;Francisco A. Squeo;
INSTITUIÇÃO:
Universidad de La Serena
Instituto de Ecología y Biodiversidad (IEB)
Programa de Doctorado en Biología y Ecología Aplicada
Centro de Estudios Avanzados en Zonas Áridas (CEAZA)
Drought tolerance, avoidance and delay are drought-resistance strategies
that allow plants to cope with drought stress along rainfall gradients. These
strategies have traditionally been evaluated at the interspecific level; where
a particular drought response strategy was associated to a particular
species. At the intraspecific level, however, a widely distributed species
along an environmental gradient may have more than one strategy to cope
with drought. This is because a single plant species is exposed to different
selection pressures along the gradient, and can thus express high
phenotypic variation in functional traits that result from ecotypic
differentiation, phenotypic plasticity or both. We used a common garden
experiment to determine the underlying evolutionary mechanisms that can
drive different drought-resistance strategies. Specifically, we tested whether
phenotypic plasticity and ecotypic differentiation lead to different
drought-resistance strategies in Encelia canescens Lam. populations. We
collected seeds from six E. canescens populations, distributed along an
aridity gradient of the Atacama Desert. Seeds were sown in individual pots,
which were randomly assigned one of two water treatments. After six
months we measured leaf mass per area, leaf and shoots number,
root:shoot ratio, leaf area ratio - LAR, plant height, net photosynthesis,
transpiration and water use efficiency- iWUE. Our results showed that all
traits, except transpiration, varied among source populations. Water
treatments affected five traits: iWUE, LAR, root:shoot ratio, number of
leaves and transpiration rate; of these, the last three differed in the
magnitude of phenotypic plasticity. We concluded that: i) Populations
subjected to more arid conditions have high levels of phenotypic plasticity in
root:shoot ratios, and low plasticity for leaf number. These differences,
coupled with low growth that appears to be genetically determined, lead to
a drought-delay strategy. ii) Populations from less arid localities were more
plastic for leaf number and less plastic for root:shoot ratios. Coupled with
high growth, this suggests that these populations have a drought avoidance
strategy. (This research was supported by grants from Chilean Millennium
Initiative (ICMP02-051-F) and CONICYT (PFB-23). D. E. Carvajal was
supported by a CONYCIT doctoral fellowship [21140050]. A. P. Loayza was
supported by a FONDECYT grant [3120123]. R. S. Rios was supported by a
CONGRESO
LXV CONGRESSO NACIONAL DE BOTÂNICA
BOTÁNICA
XXXIV ERBOT - Encontro Regional de Botânicos MG, BA, ES 18 A 24 DE OUTUBRO DE 2014 - SALVADOR - BAHIA - BRASIL
Latinoamericano de
Botânica na América Latina: conhecimento, interação e difusão
FONDECYT grant [3120121])