Mechanisms of Antarctic Vascular Plant Adaptation to Abiotic Environmental Factors I

ISSN 00954527, Cytology and Genetics, 2015, Vol. 49, No. 2, pp. 139–145. © Allerton Press, Inc., 2015. Original Ukrainian Text © I.P. Ozheredova, I.Yu. Parnikoza, O.O. Poronnik, I.A. Kozeretska, S.V. Demidov, V.A. Kunakh, 2015, published in Tsitologiya i Genetika, 2015, Vol. 49, No. 2, pp. 72–79. Mechanisms of Antarctic Vascular Plant Adaptation to Abiotic Environmental Factors I. P. Ozheredovaa, I. Yu. Parnikozab, O. O. Poronnikb, I. A. Kozeretskaa, S. V. Demidova, and V. A. Kunakhb aTaras Shevchenko National University, ul. Volodymyrska 64, Kyiv, 01033 Ukraine email: [email protected] bInstitute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, ul. Akademika Zabolotnoho 150, Kyiv, 03680 Ukraine Received November 21, 2013 Abstract—Native species of the Antarctic Deschampsia antarctica and Colobanthus quitensis exist at the limits of survival of vascular plants. Fundamental adaptations to abiotic environmental factors that qualitatively dis tinguish them from the other vascular plants of extreme regions, namely temperature, ultraviolet radiation hardiness, and their genetic plasticity in the changeable environment are discussed. Keywords: Deschampsia antarctica, Colobanthus quitensis, Antarctic, mechanisms of adaptation, stress pro tein, genome plasticity DOI: 10.3103/S0095452715020085 INTRODUCTION surface that is connected with its level of adaptation to Plant adaptation concerns hereditarily fixed con conditions of certain habitat. Pearlworts is rather rare, stitutive properties typical for plants, regardless of the and the reasons for its limited spread are not explained fact whether they are in stressful conditions not. These enough [4, 9–13]. properties become apparent on the structural and bio Populations of these vascular plants grow on poor chemical level as well. In general, the problem of plant or, quite the contrary, overrich with semidecomposed adaptation to abiotic factors is of great ecological organics soils. They experience effects of severe envi importance, since plant ability to adapt to particular ronmental conditions—low temperature, ultraviolet conditions is one of factors determining the natural rays, and moisture deficit. During the direct analysis, habitat of wild plants and possibility of their introduc we studied some biological peculiarities of Antarctic tion [1]. The Antarctic is a unique place to study nat hair grass [4]. In our work, we pay attention to the con ural adaptation mechanisms. It is entirely isolated by temporary data concerning the reaction of native the South Ocean waters and the Polar Front system, plants to the main Antarctic abiotic factor because the and vascular plants live here in extreme conditions problems of specific adaptation mechanisms of Ant strained to the limits of their possibilities as 99.5% of arctic native plants are not clear. surface is covered with continent ice and 0.3% of its area is favorable for land ecosystems [2–6]. Such sec Growing on organic soils. Initial productivity (for tions include oases of continental or the Eastern Ant mation of plant biomass) depends on peculiarities of arctic and also the narrow western coast strip of the root nutrition of plants in land ecosystems of high lat Antarctic Peninsula and islands named the maritime itudes. In guanorich areas, the growth of plants differs Antarctic. If lichen, moss, and algae dominate in much in amount of nitrogen, which slowly releases severe surroundings, formations of Antarctic grass while decomposing because of low temperature. In the tundra are spread in more favorable oases of the mari maritime Antarctic, D. antarctica and C. quitensis usu time Antarctic. The formations include two species of ally grow in guanorich territories rich particularly in native vascular plants—Antarctic hair grass (Des places of penguin rookery accumulations. This is champsia antarctica Desv., Poaceea) and Antarctic caused by a high level of nitratereductase activity of pearlworts (Colobanthus quitensis Kunth Bartl. Cary both species [14]. Thus, the ability to obtain nitrogen pophyllaceae) [4, 6–8]. These vascular plants are not on the early stages of its decomposition development fastidious and occupy all favorable places for growing: proves the success of photosynthesizing plants. rocks, hollows and corniches, places with fine clastic Accordingly, one of the adaptive characteristics of stones, beaches, etc. In particular, hair grass grows in D. antarctica and C. quitensis can be the ability to separate agglomerations or form thick cover on the absorb nitrogen on different stages of its transforma 139 140 OZHEREDOVA et al. tion. But this adaptation is not unique for Antarctic environmental temperature and launch a range of vascular plants. defense reactions, particularly the formation of free In the maritime Antarctic, D. antarctica is often fatty acids and free sugars and the synthesis of defen found in moss areas, especially Sanionia uncinata sive proteins: antifreeze, dehydrin, and chaperone (Hedw.) Loeske, which is a dominant species. At the proteins. They all are multifunctional proteins that same time, D. antarctica is able to absorb organic mat regulate processes of translation and transcription and ters from soil by 160 times faster than moss growing separate oxidation and phosphorylation during low nearby when temperature increases [14]. Plants temperature stress [23]. D. antarctica can absorb small peptides (di, tripep D. antarctica has typical biochemical adaptive tides) from soil directly by root hairs. This property mechanisms that are characteristic of plants growing gives a significant advantage to hair grass in acclima in low temperature [4]. D. antarctica and C. quitensis tion in new area but this property is typical for family can be referred to cryophytes, organisms living in low Poacae on the whole. Plants of family Caryphyllaceae temperature [25]. In general minimal photosynthesis are able to absorb minerals from interstitial water, but temperature is liquid freezing point (–1…–2°C), and root system can cause dissolving of compounds that cryophytes photosynthesize in even lower tempera are unavailable in nonsoluble form [14]. ture. Thus, for example, Pinus pumila photosynthesize ° Cold endurance. It is known that vascular plants under snow at –7 C. Antarctic lichen can photosyn thesize at –10°C [26]; as for D. antarctica, optimal include most of economic species. And they are char ° acterized by interspecies variability of cold endurance. temperature for photosynthesis is 10–12 C in natural This fact determines the thorough study of mecha conditions. For C. quitensis, this index value is not nisms of low temperature adaptation of plants that clear. Plants D. antarctica and C. quitensis endure low grow in severe climatic conditions [15, 16]. Antarctic temperature and drought as well and they are still able plants possess developed avoidance strategy. In partic to photosynthesize at the freezing point [9]. ular, this is typical for C. quitensis, since this plant General cold endurance of D. antarctica is much seems to be low clump and is mostly found near higher higher (LD50 = –26°C) than in C. quitensis (LD50 = clumps of D. antarctica or in hollows between stones –5°C) [4, 27]. avoiding direct influence of unfavorable abiotic fac One of the early reactions to cooling is oxidative tors. In some regions of the maritime Antarctic, stress, which causes disorders of enzyme activity C. quitensis is only found in some localities that are located on chloroplast and mitochondria membranes. probably the most protected from unfavorable condi Enzymes also cause the processes of oxidative and tions. photosynthetic phosphorylation. Formation of adap Besides, both plants have specific resistance or tive mechanisms of maintenance of photosynthetic endurance mechanism on the level of the whole organ activity in conditions of low temperature is realized on ism (anatomic changes). The mechanism is maintained the level of ultrastructural organization and biochem by the synthesis of some stress protein classes and also ical level of photosynthetic reactions as well [28]. We other compounds that provide for plant endurance [17, found that D. antarctica undergoes structural changes 18]. Generally, the increase of plant endurance to low in cells of leaf mesophil. Chloroplasts have irregular temperature is the complex result connected with con shape with pouches or invaginations inside of siderable rearrangement of physiological and biochem organelles and growths to enlarge the chloroplast sur ical processes and the changes of expression of a great face. This increases the productivity of photosynthe number of genes [19–22]. sis. Leaf mesophil cells of hair grass contain atypical We found that heat and cold shock cause the structures as well. They are numerous bladders of dif changes in gene activity in plant cells and other organ ferent size with concentrically located membranes. isms. Moreover, when temperature decreases, specific These formations are connected with adaptation to genes start functioning and synthesize certain pro climatic conditions of the Antarctic [29]. The data on teins. In addition to a great number of involved respective studies on C. quitensis are absent. enzymes, we isolated some families of proteins that are Earlier, it was mentioned that plants D. antarctica specifically connected with these processes. Accord and C. quitensis have different levels of cold endur ing to the scheme of Kolesnichenko et al. [23], at the ance. The difference of antifreeze activity

Load more