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PLANT PHYSIOLOG Y
UDC 582.661.56:577.19:58
STEM AND LEAF SUCCULENTS WITH CONTRASTING FROST-RESISTANCE LEVEL: ACCUMULATION PECULIARITIES OF SOME BIOLOGICALLY ACTIVE
SUBSTANCES
Tatiana Borisovna Gubanova
Nikitsky Botanical Gardens - National Scientific Centre 298648, Republic of the Crimea, Yalta, urban vil. Nikita [email protected]
Introduction
Plant cultivars capable to keep their ornamental properties during the whole year are quite important aesthetic element of parks and recreational zones of the Crimea and other southern regions. Group of succulents is rather perspective in this point. One of the reasons which makes difficult its wide usage in landscape design is a lack of information about resistance degree to unfavorable environmental conditions. Limited species variety of these ornamentally valuable plants is inconstant way of researching their frost- and winterresistance, which took place before. Literary sources present data of visual observations [1, 2, 6]. During some years frost-resistance of some specimens from families Crassulaceae and Cactaceae was investigated. As a result of these study cultivars of stem and leaf succulents with a high level of frost-resistance were revealed. Efficiency of introduction work needs not only borders of low-temperature resistance but a number of physiological and biochemical characteristics, which determine development of adaptive syndrome under influence of unfavorable wintering conditions. Such information makes possible to determine a number of characteristics for indirect and objective diagnoses of resistance to unfavorable wintering conditions.
Therefore study objective was to reveal storage peculiarities of some biologically active substances in tissues of stem and leaf succulents with different degree of frostresistance.
Objects and research methods
The following cultivars were studied to investigate storage peculiarities of biologically active substances and their function in development of cryostress for stem and leaf succulents (table 1).
Table 1
Frost-resistance of stem (Opuntia Mill., Cylindropuntia (Eng.) Knuth. Emeng.Backbg.) and leaf
(Sedum L.) succulents, its characteristic
Sedum genus Opuntia genus Cylindropuntia genus
Frost-resistant cultivars
S. reflexum L. Low critical temperature -16 °C... -18 0C O. engelmannii Eng. Low critical temperature -20 0C. -220C C. leptocaulis (Haw.) Knuth. Low critical temperature - 180C ...-230C
S. album L., Genuina Low critical temperature -18 ... -240C O. lindhimtrii SD. Low critical temperature -18 0 C...-20°C C. tunicata (Lehm.) Pfeiff. Low critical temperature -180C...-200C
S. acre L. Low critical temperature -18°C...- 200C
Mediofrost-resistant cultivars
S. luteovyride Low critical temperature -10°C...-120C O. robusta Wendl. Low critical temperature -15 °C...-16°C C. imbricata (Haw.) Knuth. Low critical temperature -140C... -180 C
S. palidum L. Low critical temperature -12°C...-140C O. leucotricha Eng. Low critical temperature -140C...-170C
S.rubrotinctum R.T. Glausen. Low critical temperature -10°C... -120C O. microdasis (Lehm.) Pfeiff. Low critical temperature -120C . ,.-150C
Methods of artificial shoot freezing in freezing chamber were applied to find out degree of frost-resistance. Gradient of temperature decreasing and increasing was 20C per hour. Assessment was carried out on 7th, 10th and 13th days [3].
Ascorbic acid concentration in tissue was determined with the help of 0,001 n 2,6 dichlorophenolindophenol solution [5]. Content of phenol compounds was found out photocolorimerically with Folin-Chicolteo reagent [5]. Correlation of growth-inhibiting and growth-stimulating substances were determined according to intensity of Lepidium sativum seeds sprouting on aqueous-alcoholic extracts made of tissues of study cultivars.
Results and discussion
As a study results of storage dynamics of ascorbic acid in water-saving tissues of stem and leaf succulents, which belong to Sedum, Opuntia and Cylindropuntia genera, a number of peculiarities was revealed in connection with their cryotemperaure resistance (table 2). In particular, concentration of ascorbic acid in tissues of both stem and leaf succulents has two maximum points; the first maximum is connected with blooming period (Sedum species - 3rd decade of May, 1st decade of June; Opuntia and Cylindropuntia - 1-2 decades of June), the second - with beginning of physiological rest. Frost-resistant cultivars (S. reflexum, O. lindhimtrii C. tunicata) are characterized by quite short vegetative period and as a result -early terms of physiological rest - autumn maximum of ascorbic acid content happens in the 2-3 decades of September.
Table 2
Variations of ascorbic acid content in water-saving tissues of stem and leaf succulents characterized by different degree of frost-resistant in a circannian cycle
Cultivars Ascorbic acid mg % per green weight
Marc h April May June July August Septem ber Octo ber Novem ber Decem ber
O. engelma nnii 21,5± 2,1 26,± 2,6 30,1± 2,6 33,8± 1,9 35,4± 2,0 35,5± 3,0 39,4± 2,3 42,5± 2,6 54,2± 3,0 46,1± 2,7
O. lindhimtrii 23,1± 3,0 24,02± 2,1 22,5± 1,9 29,7± 2,0 35,0± 2,1 25,12± 2,1 25,0± 2,1 34,6± 2,3 43,1± 2,3 38,8± 3,1
O. robusta 27,1 ± 2,5 25,3 ± 2,0 24,8± 1,7 27,4± 2,0 45,1± 3,4 37,5± 2,3 35,6± 2,7 34,85 ±3,7 41,7± 3,1 29,31± 2,4
C. tunicata 18,1 ± 1,4 16,2± 1,3 17,4± 1,1 16,4± 1,5 20,8± 2,5 21,50± 2,1 23,1± 2.3 30,28 ±2,72 31,6± 1,7 27,36± 2,0
C. imbricata 13,0± 1,3 13,5± 1,4 14,0± 2,2 13,8± 1,1 19,2± 1,3 20,6± 1,8 19,4± 1,1 17,2± 1,9 22,1± 2,2 16,6± 1,7
S. reflexum 36,8± 2,3 38,4± 2,5 65,1± 2,6 68,6± 3,3 54,2± 2,8 57,0± 2,6 58,3± 2,6 73,5± 3,7 72,3± 2,9 67,2± 2,4
S. palidum 39,9± 3,5 40,8± 3,0 57,8± 3,4 72,1± 3,2 54,8± 4,9 56,6± 3,9 55,5± 2,9 66,4± 3,8 56,3± 3,4 48,2± 3,3
For cultivars with quite low resistance to negative temperatures and continuous vegetative periods this phenomena occurred later - the end of October - beginning of November.
It was determined that stem (O. engelmanii, C. molesta) and leaf (S. reflexum, S. acre) cultivars of succulents with high level of frost-resistance are characterized by high content of ascorbic acid in tissues during autumn-winter periods; on average 15-20% more than cultivars with low frost-resistance.
Analyzing concentration of phenol compounds in water-saving tissue of stem and leaf succulents with different level of frost-resistance it was found out, leaf succulents contain more of these substances than stem cultivars. Sedum species mainly contains quercitin and its derivatives, while for Opuntia and Cylindropuntia species principal substances are xanthones.
Two maximum of phenol compounds storage are registered for both cases: May-June and November-December. Probably, activization of phenol compounds synthesis is connected not only with quantitative but with qualitative factors of these processes. As it's known a number of phenol substances contained in plants are capable to function as growth-controlling factor (depending upon structure and concentration - either inhibiting or stimulating functions) we suppose their storage in spring period is caused by beginning of growth processes, while in November-December - by realization of adaptive mechanisms to negative temperatures effect. Experiments results (sprouting of Lepidium sativum seed on aqueous-alcoholic extracts made of tissues of succulents, which contain phenol compounds) can prove this conclusion. It was found out that if air temperature regime has steady tendency of decreasing passing point of +50C (the 1st decade of November) tissue extracts of frost-resistant cultivars Sedum and Opuntia increase concentration of growth-inhibiting substances while cultivars with low frost-resistance this phenomena takes place after first frosts (the 2nd decade of November).
It turned out that frost-resistant cultivars, either stem (O. engelmannii) or leaf (S. reflexum) succulents, have more intensive synthesis of phenol compounds in comparison with not so frost-resistant cultivars such as O. robusta and S. palidum (Fig.1).
o o
... .. . _ . . . . September October November December January February
September October November December January February March '
■ S. reflexum IS. luteovwyoe Bo robusta MO engelmanii
Fig.1 Concentration of phenol compounds in tissues of cultivars of Opuntia u Sedum genera characterized by different degree of frost-resistance
These findings allowed to conclude frost-resistance of stem (cultivars of Opuntia, Cylindropuntia genera) and leaf (cultivars of Sedum genus) succulents is caused by peculiarities of their secondary metabolism: dynamics of ascorbic acid and phenol compounds
storage in water saving tissues. Tissues of plant cultivars with relatively high cryotemperature resistance contain 20-25% more during cold period than cultivars with low resistance to negative temperature do.
Analysing long-term observation of dynamics the ascorbic acid storage in study cultivars it was concluded that its concentration depends upon weather conditions of a certain year. So, warm winter 2012-2013 with a high humidity but without hardening temperature parameters caused decreasing of frost-resistance degree of stem and leaf succulents on average this difference made 5...80C, that's why ascorbic acid storage in tissues of wintering organs decreased its intensity (Fig.2).
Nevertheless, thanks to two contrasting by cryotemperature-resistance study cases of Opuntia genus it was revealed that tendency to more intensive storage of ascorbic acid in tissues of frost-resistant cultivars keeps its parameters.
60
illli
November December January February
0. engelmannii O.robucta
Fig.2 Ascorbic acid concentration in tissue of cultivars of Opuntia genus during winter periods of 20112012 and 2012-2013
Similar pattern takes place in comparison of phenol compounds in tissues of study cultivars during winter periods of 2011-2012 and 2012-2013. Probably there is cryoprotecting function of this substances with their antioxidant properties and possible participation in control of lipids peroxidation.
Conclusions
1. In terms of this research it was found out that ascorbic acid concentration in tissue of succulents has two maximum points, the first one is connected with blooming period (Sedum species - the 3rd decade of May - the 1st decade of June; species of Opuntia and Cylindropuntia - the 1-2nd decades of june), the second maximum point is explained by beginning of physiological rest (depending upon cultivar classification - October-November).
2. Frost-resistant cultivars of Sedum, Opuntia and Cylindropuntia genera are characterized by increasing of phenol compounds concentration in the beginning of cold period. Maximum content of phenols of stem and leaf succulents was registered in the coldest month on South Coast of the Crimea - February.
3. It was revealed that endogenic growth-regulators and frost-resistance level are connected. If air temperature regime has steady tendency to decreasing passing the point of 100C (the 2nd and 3rd decades of November), tissues of frost-resistant cultivars of Sedum and Opuntia increase concentration of growth-inhibiting substances while cultivars with low frostresistance have this phenomena after daily average temperatures go down passing the point of +50C (the 2nd decade of December).
November December January February
References
1. Anisimova A.I. Kaktusy. Itogi introduktsii drevesnyh rasteny v Nikitskom botanicheskom sadu za 30 let (1926-1955) // Trudy Gos.Nikit.Botan.sada. - 1957. - T. 27. - S. 25.
2. Davidova R.A. Vidy rodov Cylindropuntia i Opuntia v otkrytom grunte Ashkhabada // Izv. AN Turkm. SSR. Ser.biol. - 1963. - № 5. - S. 21-23.
3. Yelmanova T.S. Metodicheskiye rekomendatsii po kompleksnoy otsenke zimostoikosti yuzhnykh plodovykh kultur. - Yalta, 1976. - 23 s.
4. Metody tekhnokhimicheskogo kontrolya v vinodelii / Pod red. Gerzhykovoy V.G. - Simferopol: Tavrida, 2002. - 259 s.
5. Praktikum po phyziologii rasteny / Pod red. Gunara I.I.-M:"Kolos" -1972. - 166 s.
6. Speirs D.C. The cacti of western Canada // National cactus and Succulent Journal. - 1978. - V. 33. - N 4. - p. 83-84.
The article was received at editors 12.11.2014
Gubanova T.B. Stem and leaf succulents with contrasting frost-resistance level: accumulation peculiarities of some biologically active substances // Bull. of the State Nikit. Botan. Gard. - 2015. - № 115. -Р. 54-58.
The article presents dynamics results of ascorbic acid and phenol compounds storage in tissue of cultivars of Sedum, Opuntia and Cylindropuntia genera with contrasting frost-resistance level. It was found out that cultivars with a high resistance to low temperature have synthesis of phenol compounds and ascorbic acid activated as soon as cold season begins. Perhaps these substances participate in protective mechanisms under conditions of low-temperature stress.
Key words: frost-resistance; succulents; ascorbic acid;phenol compounds.
MYCOLOGY
UDC 502.73:582.28(477.75)
NEW FUNGAL SPECIES INHABITING ON DAPHNE TAURICA KOTOV (THYMELAEACEAE) IN THE CRIMEA
Vladimir Pavlovich Isikov
Nikitsky Botanical Gardens - National Scientific Centre 298648, Republic of the Crimea, the city of Yalta, urban vil.Nikita
Introduction
Daphne taurica Kotov is an endemic plant of the Crimea. It is a deciduous shrub 4080 sm (120 sm), stems in the bottom part can reach 28 mm across diameter. Bark on stems and lower branches is dark-brown, last-year's branches have dark-purple color, shoots of the current year are greenish. Leaf length makes 4-48 mm, width - 2-10 mm. Leafs are sessile, bare, leathery, quite hard, oblong - inversely egg-shaped, edges are folded, bottom is wedge-shaped short (large leaves) oblong without visible footstalk. Flowers are aromatic, yellow-white or cream-colored by length of 1-3 sm, densely growing and shape heads (3-9 flowers) on the ends of short fruiting woods with thick foliage. Bloom period is in May-June. Fruits are dark red ripened drupes, young fruits have red color. Fruiting takes place in August [2, 4, 5].
