Effects of different light intensities, CO2 concentrations, temperatures and drought stress on photosynthetic activity in two paleoendemic resurrection plant species Ramonda serbica and R-nathaliae
2015
Тип документа:
Чланак у часопису (Објављена верзија)
,
© 2014 Elsevier B.V.
Метаподаци
Приказ свих података о документуАпстракт:
Ramonda serbica and R. nathaliae are rare resurrection flowering plants
of the northern hemisphere. Although their habitats on the north-exposed
slopes of canyons and gorges are similar, those inhabited by R.
nathaliae are more varied in terms of humidity, temperature and type of
bedrock. These fine differences in ecological preference lead us to ask
whether diploid R. nathaliae is ecologically more plastic than hexaploid
R. serbica. Photosynthetic performance and fluorescence parameters are
central in evaluating a plant's capacity to withstand extreme
environmental conditions. We have compared the effects of various light
intensities, CO2 concentrations and temperatures on the photosynthetic
response of well hydrated plants of the two species. We also tracked
changes in chlorophyll a fluorescence, photochemical efficiency and
non-photochemical quenching during plant desiccation. The results have
shown that both species have a low compensation point and low dark
respiration that are indispensable for their survival at shaded and
humid sites; only there are they able to maintain an appropriate
equilibrium between positive net carbon gain and optimal water status.
Under conditions of saturating light and CO2, net CO2 uptake was always
higher in R. nathaliae that showed lower sensitivity to temperatures
between 25 degrees C and 40 degrees C. Moreover, the leaves of R.
nathaliae are amphistomatic, with smaller but more numerous stomata than
those in the hypostomatic leaves of R. serbica. These xeromorphic
characters of R. nathaliae suggest the better regulation of gas exchange
and efficiency of water use, under the conditions of everyday short
periods of direct sunlight and higher temperatures, making it possible
for this species to inhabit more open, warm and dry habitats than R.
serbica. Pronounced drought stress induced, in both species, strong
decline in fluorescence parameters, photochemical quenching and chain
electron transport rate. At the same time the exceptionally high
non-photochemical quenching provided the main and highly effective
mechanism of energy dissipation and protection against over-excitation.
Although being homoiochlorophyllous, chloroplasts in desiccated plants
are well protected from photodamage in two ways. First, the leaves are
curled inward with the palisade tissue oriented to the inner side of the
leaf. Second, the lower epidermis, that hence becomes exposed to
sunlight, is densely covered with dark non-glandular hairs and is rich
in carotenoids, anthocyanins and phenolics. All this protects desiccated
plant tissues against excessive light induced damage. (C) 2014 Elsevier
B.V. All rights reserved.
Кључне речи:
Photosynthesis; Desiccation tolerance; Chlorophyll a fluorescence; Phenolics; PolyploidyИзвор:
Environmental and Experimental Botany, 2015, 109, 63-72Финансирање / пројекти:
- Екофизиолошке адаптивне стратегије биљака у условима мултипног стреса (RS-MESTD-Basic Research (BR or ON)-173018)
- Биодиверзитет биљног света Србије и Балканског полуострва - процена, одрживо коришћење и заштита (RS-MESTD-Basic Research (BR or ON)-173030)
DOI: 10.1016/j.envexpbot.2014.08.003
ISSN: 1873-7307