Steroid compounds from two pacific starfish of the genus <Emphasis Type="Italic">Evasterias</Emphasis>

Three new steroid glycosides (evasteriosides C, D, and E) along with six known compounds were isolated from two Pacific starfish of the genus Evasterias. Evasterioside C from E. retiferacollected from the Sea of Japan was identified as (20R, 22E)-3-O-(β-D-xylopyranosyl)-24-nor-5α-cholest-22-ene-3β,6β,15α,26-pentaol 26-sulfate sodium salt. The structures of evasteriosides D and E from E. echinosoma (collected from the Gulf of Shelichov, the Sea of Okhotsk) were established as (20R, 24S)-24-O-(β-D-glucopyranosyl)-5α-cholestane-3β,6α,8,15β,24-pentaol and (20R,24S)-3,24-di-O-(β-D-xylopyranosyl)-cholest-4-ene-3β,6β,8,15α,24-pentaol, respectively. In addition, the known compounds pycnopodiosides A and C, luridoside A, 5α-cholestane-3β,6α,8,15β,16β,26-hexaol. 5α-Cholestane-3β,6α,8,15β,24-pentaol 24-sulfate sodium saltand marthasterone sulfate sodium salt were identified in E. echinosoma. The structures of the isolated compounds were established on the basis of spectroscopic analyses, using 1D and 2D NMR techniques, mass spectrometry, and some chemical transformations.     

Steroid Compounds from Far Eastern Starfishes <Emphasis Type="Italic">Henricia aspera</Emphasis> and <Emphasis Type="Italic">H. tumida</Emphasis>

Six new natural compounds were isolated from two Far Eastern starfish species, Henricia aspera and H. tumida, collected in the Sea of Okhotsk. Two new glycosylated steroid polyols were obtained from H. aspera: asperoside A and asperoside B, which were shown to be (20R,24R, 25S)-3-O-(2,3-di-O-methyl-β -D-xylopyranosyl)-24-methyl-5α-cholest-4-ene-3β, 6β,8,15α,16β,26-hexaol and (20R, 24R,25S,22E)-3-O-(2,4-di-O-methyl-β-D-xylopyranosyl)-24-methyl-5α-cholest-22-ene-3β,4β,6β,8,15α,26-hexaol, respectively. Two other glycosylated polyols, tumidoside A, with the structure elucidated as (20R, 22E)-3-O-(2,4-di-O-methyl-β -D-xylopyranosyl)-26,27-dinor-24-methyl-5α-cholest-22-ene-3β,4β,6β,8,15α,25-hexaol, and tumidoside B, whose structure was elucidated as (20R,24S)-3-O-(2,3-di-O-methyl-β-D-xylopyranosyl)-5α-cholestan-3β,4β,6β,8,15α,24-hexaol, were isolated from the two starfish species. (20R, 24S)-5α-Cholestan-3β,6β,15α,24-tetraol and (20R, 24S)-5α-cholestan-3β,6β,8,15α,24-pentaol were identified only in H. tumida. The known monoglycosides henricioside H1 and laeviuscolosides H and G were also identified in both species.     

Two new steroid glycosides from the Far East starfish <Emphasis Type="Italic">Hippasteria kurilensis</Emphasis>

Two new steroid glycosides were isolated from the Far East starfish Hippasteria kurilensis collected in the Sea of Okhotsk. They were characterized as (22E,24R)-3-O-(2-O-methyl-β-D-xylopyranosyl)-24-O-[2-O-methyl-β-D-xylopyranosyl-(1→5)-α-L-arabinofuranosyl]-5α-cholest-22-ene-3β,4β,6α,7α,8,15β,24-heptaol (kurilensoside I) and (24S)-3-O-(2-O-methyl-β-D-xylopyranosyl)-24-O-(α-L-arabinofuranosyl)-5α-cholestane-3β,4β,6β,15α,24-pentaol (kurilensoside J). In addition, the earlier known glycosides linkosides F and L1, leviusculoside G, forbeside L, desulfated echinasteroside, and granulatoside A were isolated and identified. The structures of the new compounds were established with the help of two-dimentional NMR spectroscopy and mass- spectrometry.     

Trofosides A and B and other cytostatic steroid-derived compounds from the far east starfish <Emphasis Type="Italic">Trofodiscus über</Emphasis>

Three new polar steroids identified as trofoside A, 20R,24S)-24-O-(3-O-methyl-β-D-xylopyranosyl)-3β,6α,8,15β,24-pentahydroxy-5α-cholestane, its 22(23)-dehydro derivative (trofoside B), and 15-sulfooxy-(20R,24S)-5α-cholestane-3β,6β,8,15α,24-pentaol sodium salt, were isolated fromTrofodiscus über starfish extracts collected in the Sea of Ohotsk. Two known compounds, trofoside A aglycone, (20R,24S)-3β,6α,8,15β,24-pentahydroxy-5α-cholestane, and triseramide, (20R,24R,25S,22E)-24-methyl-3β6α,8,15β-tetrahydroxy-5α-cholest-22-en-27-oic acid (2-sulfoethyl)amide sodium salt, were also found. The structures of the isolated polyoxysteroids were established from their spectra. Minimal concentrations causing degradation of unfertilized egg-cells of the sea-urchin Strongylocentrotus intermedius(C _min) and terminating the cell division at the stage of the first division (C _min embr.), as well as the concentrations causing 50% immobilization of sperm cells (OC₅₀) and inhibiting their ability to fertilize egg-cells by 50% (IC₅₀) were determined for the isolated compounds. Of three compounds highly toxic in embryos and sea-urchin sperm cells, the polyol with a sulfo group in the steroid core was the most active; two glycosides with monosaccharide chains located at C3 and C24 atoms were less toxic. Note that all the compounds with the spermiotoxic activities differently affected the embryo development. The positions of monosaccharide residues in the core considerably influence the compound activity. For example, both mono-and double chained glycosides with the monosaccharide fragment at C3 and fragments at C3 and C4 atoms are active against sea-urchin sperm cells and embryos, whereas the C24 glycosylated trofoside A does not affect embryos and displays a poor spermiotoxicity.     

New steroid glycosides from the starfish Fromia milleporella

Two new steroid glycosides from the starfish Fromia milleporella collected in the Seychelles were isolated and characterized: milleporoside A, (20R, 24R)-29-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-ethyl-5α-cholestane-3β,4β,6α,8,15β,16β,29-heptaol, and milleporoside B, (20R, 24R)-(22E)-28-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-methyl-5α-cholest-22-ene-3β,4β,6α,8,15β,16β,28-heptaol. The structures of the glycosides were determined from their spectra and a comparison with spectral characteristics of known compounds. These compounds exhibit a moderate cytostatic activity toward the embryos of the sea urchin Strongylocentrotus intermedius.     

Steroid compounds from the Far East starfish <Emphasis Type="Italic">Pteraster obscurus</Emphasis> and the ophiura <Emphasis Type="Italic">Asteronyx loveni</Emphasis>

Seven sulfated polyhydroxysteroids were isolated from the Far East starfish Pteraster obscurus and the ophiura (snake star) Asteronyx loveni (collected in the Sea of Okhotsk) and characterized: disodium and sodium salts of (20R)-24-methyl-2β-hydroxycholesta-5,24(28)-diene-3α,21-diyl disulfate, (20R)-5α-cholestane-3β,21-diyl disulfate, (20R)-3β-hydroxy-5α-cholestan-21-yl sulfate, (20R)-cholest-5-ene-3β,21-diyl disulfate, (20R)-2β-hydroxycholest-5-ene-3α,21-diyl disulfate, (20R)-cholest-5-en-3β-yl sulfate, and (20R)-5α-cholestan-3β-yl sulfate. The first four compounds turned out to be new, whereas the others were identical to the known compounds. Structures of the isolated steroids were identified by two-dimensional NMR spectroscopy and other physicochemical methods. The compounds isolated from starfish are structurally similar to typical ophiuroid metabolites, which support the opinion of some taxonomists that starfish and ophiuroids are phylogenetically related classes.     

A completed structure of the O-polysaccharide from <Emphasis Type="Italic">Shigella dysenteriae</Emphasis> type 10

The structure of the O-specific polysaccharide from Shigella dysenteriae type 10, which has been reported previously in Bioorganic chemistry (1977, vol.3, pp. 1219–1225), is refined: →2)-β-D-Manp-(1→3)-α-D-ManpNAc-(1→3)-β-L-Rhap-(1→4)-α-D-GlcpNAc-(1→.     

Synthesis of oligosaccharide fragments of mannan from <Emphasis Type="Italic">Candida albicans</Emphasis> cell wall and their BSA conjugates

3-Aminopropyl glycosides of α-D-mannopyranosyl-(1→2)-α-D-mannopyranosyl-(1→2)-α-D-mannopyranosyl-(1→2)-α-D-mannopyranose, α-D-mannopyranosyl-(1→3)-α-D-mannopyranosyl-(1→2)-α-D-mannopyranosyl-(1→2)-α-D-mannopyranose, and α-D-mannopyranosyl-(1→2)-[α-D-mannopyranosyl-(1→3)]-α-D-mannopyranosyl-(1→2)-α-D-mannopyranosyl-(1→2)-α-D-mannopyranose were efficiently synthesized starting from ethyl 2-O-acetyl(benzoyl)-3,4,6-tri-O-benzyl-1-thio-α-D-mannopyranoside, ethyl 4,6-di-O-benzyl-2-O-benzoyl-1-thio-α-D-mannopyranoside, ethyl 4,6-di-O-benzyl-2,3-di-O-benzoyl-1-thio-α-D-mannopyranoside, and 2,3,4,6-tetra-O-benzoyl-α-D-mannopyranosyl bromide. The oligosaccharide chains synthesized correspond to the three structural types of side chains of mannan from Candida albicans cell wall. A conjugate of the third pentasaccharide with bovine serum albumin was prepared using the squarate method.     

A saponin isolated from <Emphasis Type="Italic">Agapanthus africanus</Emphasis> differentially induces apoplastic peroxidase activity in wheat and displays fungicidal properties

A spirostane with an attached trisaccharide, (25R)-5α-spirostane-2α,3β,5α-triol 3-O-(O-α-l-rhamnopyranosyl-(1 → 2)-O-(β-d-galactopyranosyl-(1 → 3))-β-d-glucopyranoside), was isolated and identified from the aerial parts of Agapanthus africanus by activity-guided fractionation. Fungicidal properties of the crude extract, semi-purified fractions as well as the purified active saponin from A. africanus were screened in vitro against Fusarium oxysporum. At a concentration of 1 mg mL^?1, the crude extract and semi-purified ethyl acetate and dichloromethane fractions showed significant antifungal activity. The purified saponin inhibited the in vitro mycelial growth of F. oxysporum completely (100 %) at a concentration of 125 µg mL^?1. Furthermore, to verify previously observed induced resistance by crude extracts of A. africanus towards leaf rust, intercellular PR-protein activity was determined in wheat seedlings following foliar application of the purified saponin at 100 µg mL^?1. In vitro peroxidase enzyme activity increased significantly (60 %) in wheat seedlings 48 h after treatment with the purified saponin, demonstrating its role as an elicitor to activate a defence reaction in wheat.     

Isolation and characterization of lectin from the surface of <Emphasis Type="Italic">Grifola frondosa</Emphasis> (Fr.) S.F.Gray mycelium

From the surface of the dikaryotic mycelium of the xylotrophic basidiomycete Grifola frondosa 0917 a lectin has been isolated with a molecular mass of 68 ± 1 kDa, consisting of two subunits of 33–34 kDa each. The lectin is a hydrophilic glycoprotein with the protein: glycan ratio of 3: 1. It exhibits high affinity to native rabbit erythrocytes and to human erythrocytes of the 0 blood group, but not to trypsin-treated ones. The hemagglutination (HA) caused by lectin was not blocked by any of the 25 tested mono-, di-, and amino sugars; it was also not blocked by some of glyco derivatives. Only 13.9 μg/ml of the homogeneous preparation of a polysaccharide, a linear D-rhamnan with the structure of the repeated component →2)-β-D-Rhap-(1→3)-α-D-Rhap-(1→3)-α-D-Rhap-(1→2)-α-D-Rhap-(1→2)-α-sD-Rhap-1(→ blocked hemagglutination completely. The analysis of the amino acid composition of the lectin showed the greatest percentage of amino acids with positively charged R groups, arginine, lysine, and histidine, as well as the complete absence of sulfurcontaining amino acids, cysteine, and methionine. D-glucose and D-glucosamine were detected in the carbohydrate part. Original Russian Text ? L.V. Stepanova, V.E. Nikitina, A.S. Boiko, 2007, published in Mikrobiologiya, 2007, Vol. 76, No. 4, pp. 488–493.     

Anionic polymers of the cell wall of <Emphasis Type="Italic">Streptomyces</Emphasis> sp. VKM Ac-2534

The cell wall of Streptomyces sp. VKM Ac-2534, the causative agent of common scab in potato tubers, which does not synthesize thaxtomin and is phylogenetically close to phytopathogen Streptomyces setonii sp. ATCC 25497, contains two anionic carbohydrate-containing polymers. The major polymer is teichuronic acid, whose repeating unit is disaccharide → 4)-β-D-ManpNAc3NAcyA-(1 → 3)-α-D-GalpNAc-(1→, where Acy is a residue of acetic or L-glutamic acid. The polymer of such structure has been found in Gram-positive bacteria for the first time. The minor polymer is teichoic acid [1,5-poly(ribitol phosphate)], in which a part of the ribitol residues are glycosylated at C4 with β-D-Glcp and, probably, with β-D-GlcpNAc and some residues are O-acylated with Lys residues. The structures were proved by chemical and NMR spectroscopic methods. It is likely that the presence of acidic polysaccharides on the surface of the phytopathogenic streptomycete is necessary for its attachment to the host plant.     

(22<Emphasis Type="Italic">R</Emphasis>,23<Emphasis Type="Italic">R</Emphasis>)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one: Improved synthesis and toxicity to MCF-7 cells

The chemical synthesis of (22R,23R)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one from (22A)-3β-acetoxy-5α-ergosta-7,14,22-triene was improved. The stages of obtaining and isomerization of (22A)-3β-acetoxy-14α15α-epoxy-5α-ergosta-7,22-diene were optimized. The introduction of (22R,23R)-epoxide cycle was carried out by alkaline treatment of intermediate (22S,23R)-3β,23-diacetoxy-22-iodo-5α-ergost-8(14)-en-15-one. In cells of human breast carcinoma MCF-7, (22R,23R)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one showed a high toxicity (TC₅₀ = 0.4±0.1 μM at 48-h incubation in serum-free medium).     

Pancreatic lipase inhibitory activity of monogalactosyldiacylglycerols isolated from the freshwater microalga <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis>

Chemical investigation of the freshwater microalga Chlorella sorokiniana led to the isolation of a monogalactosyldiacylglycerol (MGDG)-rich fraction possessing dose-dependent inhibitory activity against pancreatic lipase activity. The MGDG-rich fraction contains 12 MGDGs identified by LC/HRMS analysis. Among them, three MGDGs were new compounds, namely, (2S)-1-O-(7Z,10Z-hexadecadienoyl)-2-O-(7Z,10Z,13Z-hexadecatrienoyl)-3-O-β-D-galactopyranosylglycerol (1), (2S)-1-O-linoleoyl-2-O-(7Z,10Z-hexadecadienoyl)-3-O-β-D-galactopyranosylglycerol (6), and (2S)-1-O-oleoyl-2-O-(7Z,10Z-hexadecadienoyl)-3-O-β-D-galactopyranosylglycerol (8). The major galactolipids were isolated by semipreparative HPLC and tested for their effect toward pancreatic lipase inhibitory activity. All the tested MGDGs showed significant reduction of pancreatic lipase activity indicating possible beneficial use for management of lipase-related disorders such as obesity.     

The preparative method for 2-fluoroadenosine synthesis

The preparative method for the synthesis of 2-fluoroadenosine starting from commercially available guanosine was developed. It included the intermediate formation of 2-amino-6-azido-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine, which was isolated exclusively in the tetrazolo[5,1-i]-form {5-amino-7-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-7H -tetrazolo[5,1-i]purine}. The latter compound was converted by the Schiemann reaction to 6-azido-2-fluoro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine, which was isolated at an 80% yield after careful optimization of the process. The IR and ¹H NMR spectroscopy data indicated the 6-azido-2-fluoropurine structure of the aglycone. The catalytic reduction of the azido group in 6-azido-2-fluoro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine to the amino moiety and the subsequent deacetylation by the routine procedure resulted in 2-fluoroadenosine at a total yield of 74%.     

Effect of gamma radiation on the expression of mRNA growth factors in glycerol cryopreserved human amniotic membrane

Human amniotic membrane (HAM) due to its high biocompatibility, low immunogenicity, anti-microbial, anti-viral properties as well as the presence of growth factors has been used in various clinical applications. The growth factors play an important role in wound healing. The current study aimed to explore the effect of 15 kGy gamma radiation dose on selected growth factors and receptors mRNA present in HAM. Eight growth factors, namely, EGF, HGF, KGF, TGF-α, TGF-β1, TGF-β2, TGF-β3 and bFGF and two growth factor receptors, HGFR and KGFR were evaluated in this study. The total RNA was extracted and converted to complimentary DNA using commercial kits. Subsequently, the mRNA expressions of these growth factors were evaluated using real-time PCR and the results were statistically analyzed using REST-MCS software. This study confirmed the presence of these mRNA growth factors and receptors in fresh, glycerol cryopreserved and irradiated glycerol cryopreserved HAM. In glycerol cryopreserved HAM, the results showed up-regulation of HGF and bFGF and down-regulation of EGF, HGFR, KGF, KGFR, TGF-α, TGF-β1, TGF-β2 and TGF-β3 relative to the fresh HAM which acted as the control, whereas in irradiated glycerol cryopreserved HAM, the results showed up-regulation of EGF, HGF, KGF, KGFR, TGF-β1, TGF-β2 and TGF-β3 and down-regulation of HGFR, TGF-α and bFGF relative to the glycerol cryopreserved HAM which acted as the control. However, these mRNA expressions did not show any statistical significant difference compared to the control groups. This study concluded that a dose of 15 kGy of gamma radiation did not affect the mRNA expression for the growth factors’ and receptors’ in the glycerol cryopreserved HAM.     

Enzymatic synthesis of lactosylated and sialylated derivatives of epothilone A

Epothilone A is a derivative of 16-membered polyketide natural product, which has comparable chemotherapeutic effect like taxol. Introduction of sialic acids to these chemotherapeutic agents could generate interesting therapeutic glycoconjugates with significant effects in clinical studies. Since, most of the organisms biosynthesize sialic acids in their cell surface, they are key mediators in cellular events (cell-cell recognition, cell-matrix interactions). Interaction between such therapeutic sugar parts and cellular polysaccharides could generate interesting result in drugs like epothilone A. Based on this hypothesis, epothilone A glucoside (epothilone A 6-O-β-D-glucoside) was further decorated by conjugating enzymatically galactose followed by sialic acids to generate epothilone A 7-O-β-D-glucopyranosyl, 4′-O-α-D-galactoside i.e., lactosyl epothilone A (lac epoA) and two sialosides of epothilone A namely epothilone A 7-O-β-D-glucopyranosyl, 4′-O-α-D-galactopyranosyl 3″-O-α-N-acetyl neuraminic acid and epothilone A 7-O-β-D-glucopyranosyl, 4′-O-α-D-galactopyranosyl 6″-O-α-N-acetylneuraminic acid i.e., 3′sialyllactosyl epothilone A: 3′SL-epoA, and 6′sialyllactosyl epothilone A: 6′SL-epoA, respectively. These synthesized analogs were spectroscopically analyzed and elucidated, and biologically validated using HUVEC and HCT116 cancer cell lines.     

Neuro-and psychotropic activity of <Emphasis Type="Italic">N</Emphasis>-uronoylamino acids and <Emphasis Type="Italic">N</Emphasis>-uronoylpeptides

Peculiarities of the rat behavior were studied in a series of experimental stress models after a systemic administration of new N-uronoyl derivatives of amino acids. The psychotropic effect was shown to be determined by the nature of the amino acid fragment. N-(1,2:3,4-Di-O-isopropylidene-α-D-galactopyraneuronoyl)-glycylglycine exhibited an anxiolytic effect more pronounced than that of pyracetam, whereas N-(1,2:3,4-di-O-isopropilidene-α-D-galactopyranuronoyl)-glycylglutamic acid has antidepressant action stronger than that of amitriptyline. Mechanisms for the psychotropic effects of the examined derivatives are discussed.     

Cell wall glycopolymers of type strains from three species of the genus <Emphasis Type="Italic">Actinoplanes</Emphasis>

The structures of cell wall glycopolymers from the type strains of three Actinoplanes species were investigated using chemical methods, NMR spectroscopy, and mass spectrometry. Actinoplanes digitatis VKM Ac-649^T contains two phosphate-containing glycopolymers: poly(diglycosyl-1-phosphate) →6)-α-D-GlcpNAc-(1-P-6)-α-D-GlcpN-(1→ and teichoic acid →1)-sn-Gro-(3-P-3)-β-[β-D-GlcpNAc-(1→2]-D-Galp-(1→. Two glycopolymers were identified in A. auranticolor VKM Ac-648^T and A. cyaneus VKM Ac-1095^T: minor polymer–unsubstituted 2,3-poly(glycerol phosphate), widely abundant in actinobacteria (Ac-648^T), and mannan with trisaccharide repeating unit →2)-α-D-Manp-(1→2)-α-D-Manp(1→6)-α-D-Manp-(1→(Ac-1095^T). In addition, both microorganisms contain a teichuronic acid of unique structure containing a pentasaccharide repeating unit with two residues of glucopyranose and three residues of diaminouronic acids in D-manno- and/or D-gluco-configuration. Each of the strains demonstrates peculiarities in the structure of teichuronic acid with respect to the ratio of diaminouronic acids and availability and location of O-methyl groups in glucopyranose residues. All investigated strains contain a unique set of glycopolymers in their cell walls with structures not described earlier for prokaryotes.     

Substituted 16α,17α-cyclohexanopregnanes: the anionic oxy-Cope rearrangement of 3β-<Emphasis Type="Italic">tert</Emphasis>-butyldimethylsilyloxy-19-hydroxy-19-vinyl-16α,17α-cyclohexapregn-5-en-20-one

(19R)-and (19S)-tert-Butyldimethylsilyl (TBS) ethers of 19-hydroxy-19-vinyl-16α,17α-cyclohexanopregn-5-en-20-ones were synthesized. These compounds containing the 1,5-oxydienoic motif were subjectedto the anionic oxy-Cope rearrangement to obtain 3β-TBS ether of 6β-(3-oxopropyl)-16α,17α-cyclohexano-19-norpregn-5(10)-en-20-one. The structures of the compounds synthesized were confirmed by the analysis of their ¹H and ¹³C NMR spectra.     

Overexpression of <Emphasis Type="Italic">MeDREB1D</Emphasis> confers tolerance to both drought and cold stresses in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

Cassava (Manihot esculenta) is an important tropical crop with extraordinary tolerance to drought stress but few reports on it. In this study, MeDREB1D was significantly and positively induced by drought stress. Two allelic variants of the gene named MeDREB1D(R-2) and MeDREB1D(Y-3) were identified. Overexpressing MeDREB1D(R-2) and MeDREB1D(Y-3) in Arabidopsis resulted in stronger tolerance to drought and cold stresses. Under drought stress, transgenic plants had more biomass, higher survival rates and less MDA content than wild-type plants. Under cold stress, transgenic plants also had higher survival rates than wild-type plants. To further characterize the molecular function of MeDREB1D, we conducted an RNA-Seq analysis of transgenic and wild-type Arabidopsis plants. The results showed that the Arabidopsis plants overexpressing MeDREB1D led to changes in downstream genes. Several POD genes, which may play a vital role in drought and cold tolerance, were up-regulated in transgenic plants. In brief, these results suggest that MeDREB1D can simultaneously improve plant tolerance to drought and cold stresses.