Effects of Chilling Temperature on the Activity of Enzymes of Sucrose Synthesis and the Accumulation of Saccharides in Leaves of Three Sugarcane Cultivars Differing in Cold Sensitivity

The effects of short-term exposure to chilling temperature (10 °C) on sucrose synthesis in leaves of the cold-tolerant sugarcane cultivars Saccharum sinense R. cv. Yomitanzan and Saccharum sp. cv. NiF4, and the cold-sensitive cultivar S. officinarum L. cv. Badila were studied. Plants were grown at day/night temperatures of 30/25 °C, and then shifted to a constant day/night temperature of 10 °C. After 52-h exposure to the chilling temperature, sucrose content in the leaves of NiF4 and Yomitanzan showed a 2.5- to 3.5-fold increase relative to that of the control plants that had been left on day/night temperatures of 30/25 °C. No such increase was observed in Badila leaves. Similarly, starch content in the leaves of NiF4 and Yomitanzan was maintained high, but starch was depleted in Badila leaves after the 52-h exposure. During the chilling temperature, sucrose phosphate synthase (SPS; E.C.2.4.1.14) activity was relatively stable in the leaves of NiF4 and Yomitanzan, whereas in Badila leaves SPS activity significantly decreased. There was no significant change in cytosolic fructose-1,6-bisphosphatase activity for the three cultivars at the chilling temperature. This supports the hypothesis that: (1) on exposure to chilling temperature, sucrose content in sugarcane leaves is determined by the photosynthetic rate in the leaves, and is not related to SPS activity; (2) SPS activity in sugarcane leaves at chilling temperature is to be determined by sugar concentration in the leaves.     

Protective role of salicylic acid applied before cold stress on antioxidative system and protein patterns in barley apoplast

This study was carried out to better understand the role of salicylic acid (SA) applied before cold stress in the cold tolerance mechanism. Two barley (Hordeum vulgare) cultivars, cold-sensitive (Akhisar) and cold-tolerant (Tokak), were used and 0.1 mM SA was applied to 7-d-old barley seedlings growing under control conditions (20/18 °C). The seedlings were transferred to cold chamber (7/5 °C) at the age 14, 21, and 28 d. After three days, the leaves were harvested to determine the activities of apoplastic antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) and ice nucleation activity and electrophoretic patterns of apoplastic proteins. Cold treatment decreased the activities of all enzymes in cold-sensitive cultivar, however, it increased CAT and POX activities in cold-tolerant cultivar. Exogenous SA increased enzyme activities in both cultivars. Ice nucleation activity increased by cold treatment, especially in 17-d-old seedlings in both cultivars. In addition, SA treatment increased ice nucleation activity in all examined samplings in both cultivars. SA treatment caused accumulation or de novo synthesis of some apoplastic proteins. The results of the present study show that exogenous SA can improve cold tolerance by regulating the activities of apoplastic antioxidative enzymes, ice nucleation activity, and the patterns of apoplastic proteins.     

Identification of a metabolic bottleneck for cold acclimation in Arabidopsis thaliana

Central carbohydrate metabolism of Arabidopsis thaliana is known to play a crucial role during cold acclimation and the acquisition of freezing tolerance. During cold exposure, many carbohydrates accumulate and a new metabolic homeostasis evolves. In the present study, we analyse the diurnal dynamics of carbohydrate homeostasis before and after cold exposure in three natural accessions showing distinct cold acclimation capacity. Diurnal dynamics of soluble carbohydrates were found to be significantly different in cold-sensitive and cold-tolerant accessions. Although experimentally determined maximum turnover rates for sucrose phosphate synthase in cold-acclimated leaves were higher for cold-tolerant accessions, model simulations of diurnal carbohydrate dynamics revealed similar fluxes. This implied a significantly higher capacity for sucrose synthesis in cold-tolerant than cold-sensitive accessions. Based on this implication resulting from mathematical model simulation, a critical temperature for sucrose synthesis was calculated using the Arrhenius equation and experimentally validated in the cold-sensitive accession C24. At the critical temperature suggested by model simulation, an imbalance in photosynthetic carbon fixation ultimately resulting in oxidative stress was observed. It is therefore concluded that metabolic capacities at least in part determine the ability of accessions of Arabidopsis thaliana to cope with changes in environmental conditions.     

A novel thermostable alpha-galactosidase from the thermophilic fungus Thermomyces lanuginosus CBS 395.62/b: purification and characterization

High levels of an extracellular alpha-galactosidase are produced by the thermophilic fungus Thermomyces lanuginosus CBS 395.62/b when grown in submerse culture and induced by sucrose. The enzyme was purified 114-fold from the culture supernatant by (NH(4))(2)SO(4) fractionation, and by chromatographical steps including Sepharose CL-6B gel filtration, DEAE-Sepharose FF anion-exchange, Q-Sepharose FF anion-exchange and Superose 12 gel filtration. The purified enzyme exhibits apparent homogeneity as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and iso-electric focusing (IEF). The native molecular weight of the monomeric alpha-galactosidase is 93 kDa with an isoelectric point of 3.9. The enzyme displays a pH and temperature optimum of 5-5.5 and 65 degrees C, respectively. The purified enzyme retains more than 90% of its activity at 45 degrees C in a pH range from 5.5 to 9.0. The enzyme proves to be a glycoprotein and its carbohydrate content is 5.3%. Kinetic parameters were determined for the substrates p-nitrophenyl-alpha-galactopyranoside, raffinose and stachyose and very similar K(m) values of 1.13 mM, 1.61 mM and 1.17 mM were found. Mn(++) ions activates enzyme activity, whereas inhibitory effects can be observed with Ca(++), Zn(++) and Hg(++). Five min incubation at 65 degrees with 10 mM Ag(+) results in complete inactivation of the purified alpha-galactosidase. Amino acid sequence alignment of N-terminal sequence data allows the alpha-galactosidase from Thermomyces lanuginosus to be classified in glycosyl hydrolase family 36.     

Diurnal water balance of the cowpea fruit

The vascular network of the cowpea (Vigna unguiculata [L.] Walp.) fruit exhibits the anatomical potential for reversible xylem flow between seeds, pod, and parent plant. Feeding of cut shoots with the apoplast marker acid fuchsin showed that fruits imported regularly via xylem at night, less frequently in early morning, and only rarely in the afternoon. The dye never entered seeds or inner dorsal pod strands connecting directly to seeds. Root feeding (early morning) of intact plants with ³²PO₄ or ³H₂O rapidly (20 min) labeled pod walls but not seeds, consistent with uptake through xylem. Weak subsequent (4 hours) labeling of seeds suggested slow secondary exchange of label with the phloem stream to the fruit. Vein flap feeding of subtending leaves with [¹⁴C]sucrose, ³H₂O, and ³²PO₄ labeled pod and seed intensely, indicating mass flow in phloem to the fruit. Over 90% of the ¹⁴C and ³H of fruit cryopuncture phloem sap was as sucrose and water, respectively. Specific ³H activities of transpired water collected from fruits and peduncles were assayed over 4 days after feeding ³H₂O to roots, via leaf flaps, or directly to fruits. The data indicated that fruits transpired relatively less xylem-derived (apoplastic) water than did peduncles, that fruit and peduncle relied more heavily on phloem-derived (symplastic) water for transpiration in the day than at night, and that water diffusing back from the fruit was utilized in peduncle transpiration, especially during the day. The data collectively support the hypothesis of a diurnally reversing xylem flow between developing fruit and plant.     

Isolation and characterization of cold-regulated transcriptional activator <Emphasis Type="Italic">LpCBF3</Emphasis> gene from perennial ryegrass (<Emphasis Type="Italic">Lolium perenne</Emphasis> L.)

In plants, low temperatures can activate the CBF cold response pathway playing a prominent role in cold acclimation by triggering a set of cold-related gene expressions. CBF homologous gene, designated as LpCBF3, from a cold-tolerant perennial ryegrass (Lolium perenne L.) accession was identified. It carries the sequences for nuclear localization signal (NLS), AP2 DNA-binding domains and an acidic activation present in most of the plant CBF proteins. Southern analysis indicated the presence of three homologs of LpCBF3 gene in perennial ryegrass genome, and only one amino acid variation in LpCBF3 protein between cold-tolerant and -sensitive perennial ryegrass accessions. In their putative promoter regions, some differential regions were found. Northern blotting and RT-PCR analysis found that LpCBF3 reached the highest expression after 1.5 h of cold treatment (4 degrees C). The COR homologous gene, a downstream gene of CBF, can be expressed in the plant stem of cold-tolerant perennial ryegrass accessions without cold treatment. Without cold treatment, the COR gene cannot be activated in cold-sensitive perennial ryegrass accessions. Cold treatment can prompt expression levels of COR homologous genes in both perennial ryegrass accessions. In transgenic Arabidopsis, the overexpression of LpCBF3 with the 35S promoter resulted in dwarf-like plants, later flowering and greater freezing tolerance.     

Diurnal patterns of growth and transient reserves of sink and source tissues are affected by cold nights in barley

Barley is described to mostly use sucrose for night carbon requirements. To understand how the transient carbon is accumulated and utilized in response to cold, barley plants were grown in a combination of cold days and/or nights. Both daytime and night cold reduced growth. Sucrose was the main carbohydrate supplying growth at night, representing 50–60% of the carbon consumed. Under warm days and nights, starch was the second contributor with 26% and malate the third with 15%. Under cold nights, the contribution of starch was severely reduced, due to an inhibition of its synthesis, including under warm days, and malate was the second contributor to C requirements with 24–28% of the total amount of carbon consumed. We propose that malate plays a critical role as an alternative carbon source to sucrose and starch in barley. Hexoses, malate, and sucrose mobilization and starch accumulation were affected in barley elf3 clock mutants, suggesting a clock regulation of their metabolism, without affecting growth and photosynthesis however. Altogether, our data suggest that the mobilization of sucrose and malate and/or barley growth machinery are sensitive to cold.     

Effects of exogenous abscisic acid (ABA) on cucumber seedling leaf carbohydrate metabolism under low temperature

Seedlings with four true leaves of cucumbers (Cucumis sativus L.), Guonong No.25 (a cold-tolerant cultivar) and Guonong No.41 (a cold sensitive cultivar), were grown under normal or low temperature conditions: 25°C/18°C or 15°C/8°C (day/night). The seedlings of Guonong No.25 under low temperature were also treated with or without exogenous ABA. The purpose of our study was to find out the effects of low temperature and exogenous ABA application on the carbohydrate metabolism in the cucumber plants. Time course changes of carbohydrate contents and activities of stachyose synthase and alkaline α-galactosidase in the seedling leaves were investigated after the treatment. Our results show that compared to the seedlings under temperatures of 25°C/18°C, the seedlings of the both tested genotypes under 15°C/8°C (day/night) have significantly higher contents of all measured soluble carbohydrates. Significant difference in stachyose synthase activity is observed between the two genotypes under normal temperature or low temperature. Under normal temperature, leaf stachyose synthase activity in Guonong No.41 is higher than that in Guonong No.25. The stachyose synthase activity of Guonong No.41 decreases sharply under low temperature, but that of Guonong No.25 increases 3 days after treatment and then decreases to the original level. In contrast, there is no significant genotypic difference in alkaline α-galactosidase activity. Additionally, compared to the control seedlings treated with 0 μM ABA, the seedlings treated with 50 and 150 μM ABA accumulate substantial amounts of all tested soluble carbohydrates except galactose whereas 250 μM ABA treated seedlings show decreased levels of all these soluble carbohydrates. Stachyose synthase activity increases significantly upon 50 and 150 μM ABA treatments. Fan-zhen Menga, Li-ping Hu, and Shao-hui Wang contributed equally to the paper.     

Conditions of formation, purification, and characterization of an alpha-galactosidase of Trichoderma reesei RUT C-30.

Trichoderma reesei RUT C-30 formed an extracellular alpha-galactosidase when it was grown in a batch culture containing lactose or locust bean gum as a carbon source. Short-chain alpha-galactosides (melibiose, raffinose, stachyose), as well as the monosaccharides galactose, dulcitol, arabinose, and arabitol, also induced alpha-galactosidase activity both when they were used as carbon sources (at a concentration of 1%) in batch cultures and in resting mycelia (at concentrations in the millimolar range). The addition of 50 mM glucose did not affect the induction of alpha-galactosidase formation by galactose. alpha-Galactosidase from T. reesei RUT C-30 was purified to homogeneity from culture fluids of galactose-induced mycelia. The active enzyme was a 50 +/- 3-kDa, nonglycosylated monomer which had an isoelectric point of 5.2. It was active against several alpha-galactosides (p-nitrophenyl-alpha-D-galactoside, melibiose, raffinose, and stachyose) and galactomannan (locust bean gum) and was inhibited by the product galactose. It released galactose from locust bean gum and exhibited synergism with T. reesei beta-mannanase. Its activity was optimal at pH 4, and it displayed broad pH stability (pH 4 to 8). Its temperature stability was moderate (60 min at 50 degrees C resulted in recovery of 70% of activity), and its highest level of activity occurred at 60 degrees C. Its action on galactomannan was increased by the presence of beta-mannanase.     

东乡野生稻苗期耐冷性的遗传分析

以强耐冷材料龙稻5号（Oryza sativa ssp.japonica）和冷敏感材料协青早B（O.sativa ssp.indica）为对照品种,以萎蔫率和死苗率为鉴定指标,利用江西东乡普通野生稻（O.rufipogon）/协青早B//协青早B构建的回交重组自交系（backcross in-bred lines,BILs）群体（BC1F9）进行苗期耐冷性鉴定和遗传分析。结果表明,10°C冷处理7天后,228个BILs群体的平均萎蔫率为67.4%,平均死苗率为70.8%。将死苗率≤20%的株系,在更低温度（8°C昼/5°C夜）下处理5天,结果显示5243和5335为强耐冷材料,可用于构建东乡野生稻QTL（quantitative traitloci）近等基因系（near-isogenic lines,NILs）。实验结果显示,群体萎蔫率和死苗率均呈偏态的连续分布,暗示东乡野生稻苗期耐冷性表现为质量-数量性状遗传特征,由主基因-多基因控制。     

Grafting helps improve photosynthesis and carbohydrate metabolism in leaves of muskmelon

The most important quality for muskmelon (Cucumis melo L.) is their sweetness which is closely related to the soluble sugars content. Leaves are the main photosynthetic organs in plants and thus the source of sugar accumulation in fruits since sugars are translocated from leaves to fruits. The effects of grafting muskmelon on two different inter-specific (Cucurbita maxima×C. moschata) rootstocks was investigated with respect to photosynthesis and carbohydrate metabolism. Grafting Zhongmi1 muskmelon on RibenStrong (GR) or Shengzhen1 (GS) rootstocks increased chlorophyll a, chlorophyll b and chlorophyll a+b content and the leaf area in middle and late developmental stages of the plant compared to the ungrafted Zhongmi1 check (CK). Grafting enhanced the net photosynthesis rate, the stomatal conductance, concentration of intercellular CO(2) and transpiration rate. Grafting influenced carbohydrates contents by changing carbohydrate metabolic enzymes activities which was observed as an increase in acid invertase and neutral invertase activity in the functional leaves during the early and middle developmental stages compared to CK. Grafting improved sucrose phosphate synthase and stachyose synthase activities in middle and late developmental stages, thus translocation of sugars (such as sucrose, raffinose and stachyose) in GR and GS leaves were significantly enhanced. However, compared with CK, translocation of more sugars in grafted plants did not exert feedback inhibition on photosynthesis. Our results indicate that grafting muskmelon on inter-specific rootstocks enhances photosynthesis and translocation of sugars in muskmelon leaves.     

Characterization and biotechnological application of an acid alpha-galactosidase from Tachigali multijuga Benth. seeds

Tachigali multijuga Benth. seeds were found to contain protein (364 mg g(-1)dwt), lipids (24 mg g(-1)dwt), ash (35 mg g(-1)dwt), and carbohydrates (577 mg g(-1)dwt). Sucrose, raffinose, and stachyose concentrations were 8.3, 3.0, and 11.6 mg g(-1)dwt, respectively. alpha-Galactosidase activity increased during seed germination and reached a maximum level at 108 h after seed imbibition. The alpha-galactosidase purified from germinating seeds had an M(r) of 38,000 and maximal activity at pH 5.0-5.5 and 50 degrees C. The enzyme was stable at 35 degrees C and 40 degrees C, but lost 79% of its activity after 30 min at 50 degrees C. The activation energy (E(a)) values for p-nitrophenyl-alpha-d-galactopyranoside (pNPGal) and raffinose were 13.86 and 4.75 kcal mol(-1), respectively. The K(m) values for pNPGal, melibiose, raffinose, and stachyose were 0.45, 5.37, 39.62 and 48.80 mM, respectively. The enzyme was sensitive to inhibition by HgCl(2), SDS, AgNO(3), CuSO(4), and melibiose. d-Galactose was a competitive inhibitor (K(i)=2.74 mM). In addition to its ability to hydrolyze raffinose and stachyose, the enzyme also hydrolyzed galactomannan.     

Identification and analysis of QTLs controlling cold tolerance at the reproductive stage and validation of effective QTLs in cold-tolerant genotypes of rice (Oryza sativa L.)

Low temperature or cold stress is one of the major constraints of rice production and productivity in temperate rice-growing countries and high-altitude areas in the tropics. Even though low temperature affects the rice plant in all stages of growth, the percent seed set is damaged severely by cold and this reduces the yield potential of cultivars significantly. In this study, a new source of cold-tolerant line, IR66160-121-4-4-2, was used as a donor parent with a cold-sensitive cultivar, Geumobyeo, to produce 153 F₈ recombinant inbred lines (RILs) for quantitative trait locus (QTL) analysis. QTL analysis with 175 polymorphic simple sequence repeat (SSR) markers and composite interval mapping identified three main-effect QTLs (qPSST-3, qPSST-7, and qPSST-9) on chromosomes 3, 7, and 9. The SSR markers RM569, RM1377, and RM24545 were linked to the identified QTLs for cold tolerance with respect to percent seed set using cold-water (18–19°C) irrigation in the field and controlled air temperature (17°C) in the greenhouse. The total phenotypic variation for cold tolerance contributed by the three QTLs was 27.4%. RILs with high percent seed set under cold stress were validated with linked DNA markers and by haplotype analysis that revealed the contribution of progenitor genomes from the tropical japonica cultivar Jimbrug (Javanica) and temperate japonica cultivar Shen-Nung89-366. Three QTLs contributed by the cold-tolerant parent were identified which showed additive effect on percent seed set under cold treatment. This study demonstrated the utility of a new phenotyping method as well as the identification of SSR markers associated with QTLs for selection of cold-tolerant genotypes to improve temperate rice production.     

Influence of repeated passive body heating on subsequent night sleep in humans

Experiments were carried out on four healthy male subjects in two separate sessions: (a) A baseline period of two consecutive nights, one spent at thermoneutrality [operative temperature (To) = 30 degrees C, dew-point temperature (Tdp) = 7 degrees C, air velocity (Va) = 0.2 m.s-1] and the other in hot condition (To = 35 degrees C, Tdp = 7 degrees C, Va = 0.2 m.s-1). During the day, the subjects lived in their normal housing and were engaged in their usual activities. (b) An acclimation period of seven consecutive daily heat exposures from 1400 to 1700 hours (To = 44 degrees C, Tdp = 29 degrees C, Va = 0.3 m.s-1). During each night, the subjects slept in thermoneutral or in hot conditions. The sleep measurements were: EEG from two sites, EOG from both eyes, EMG and EKG. Esophageal and ten skin temperatures were recorded continuously during the night. In the nocturnal hot conditions, a sweat collection capsule recorded the sweat gland activity in the different sleep stages. Results showed that passive body heating had no significant effect on the sleep structure of subsequent nights at thermoneutrality. In contrast, during nights at To = 35 degrees C an effect of daily heat exposure was observed on sleep. During the 2nd night of the heat acclimation period, sleep was more restless and less efficient than during the baseline night. The rapid eye movement sleep duration was reduced, while the rate of transient activation phases observed in sleep stage 2 increased significantly. On the 7th night, stage 4 sleep increased (+68%) over values observed during the baseline night.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survey of Some Actinomycetales for α-Galactosidase Activity

The enzyme alpha-galactosidase offers potential to (i) eliminate possibly the flatus-inducing factor(s) in edible beans, (ii) eliminate raffinose during beet-sugar processing, and (iii) determine raffinose analytically. Accordingly, 20 genera of the order Actinomycetales Buchanan 1917 were tested for evidence of alpha-galactosidase activity. Test filtrates were prepared with a medium containing D-galactose and soybean meal. Enzyme activity was demonstrated through cellulose thin-layer chromatography. Of 123 strains tested, 28 produced extracellular alpha-galactosidase. Almost all were streptomycetes. Members of the genera Actinoplanes Couch 1950, Micromonospora varphiOrskov 1923, and Promicromonospora Krasil'nikov et al. 1961 also exhibited alpha-galactosidase activity. Additional tests led to the selection of five strains whose filtrates degraded melibiose, raffinose, and stachyose but not lactose and sucrose. Tests also were made with several soybean preparations.     

Purification and characterization of the raffinose oligosaccharide chain elongation enzyme,galactan : galactan galactosyltransferase (GGT), from Ajuga reptans leaves

Galactan: galactan galactosyltransferase (GGT), an enzyme involved in the biosynthesis of the long-chain raffinose family of oligosaccharides (RFOs) in Ajuga reptans, catalyses the transfer of an alpha-galactosyl residue from one molecule of RFO to another one resulting in the next higher RFO oligomer. This novel galactinol (alpha-galactosyl-myo-inositol)-independent alpha-galactosyltransferase is responsible for the accumulation of long-chain RFOs in vivo. Warm treatment (20 degrees C) of excised leaves resulted in a 34-fold increase of RFO concentration and a 200-fold increase of GGT activity after 28 days. Cold treatment (10 degrees C/3 degrees C day/night) resulted in a 26- and 130-fold increase, respectively. These data support the role of GGT as a key enzyme in the synthesis and accumulation of long-chain RFOs. GGT was purified from leaves in a 4-step procedure which involved fractionated precipitation with ammonium sulphate as well as lectin affinity, anion exchange, and size-exclusion chromatography and resulted in a 200-fold purification. Purified GGT had an isoelectric point of 4.7, a pH optimum around 5, and its transferase reaction displayed saturable concentration dependence for both raffinose (Km = 42 mM) and stachyose (Km = 58 mM). GGT is a glycoprotein with a 10% glycan portion. The native molecular mass was 212 kDa as determined by size-exclusion chromatography. Purified GGT showed one single active band after native PAGE or IEF separation, respectively, which separated into three bands on SDS-PAGE at 48 kDa, 66 kDa, and 60 kDa. The amino acid sequence of four tryptic peptides obtained from the major 48-kDa band showed a high homology to plant alpha-galactosidase (EC 3.2.1.22) sequences. GGT differed, however, in its substrate specificity from alpha-galactosidases; it neither hydrolysed nor transferred alpha-galactosyl-groups from melibiose, galactinol, UDP-galactose, manninotriose, and manninotetrose. Galactinol, sucrose, and galactose inhibited the GGT reaction considerably at 10-50 mM.     

东乡野生稻苗期耐冷性的遗传分析

以强耐冷材料龙稻5号(Oryza sativa ssp. japonica)和冷敏感材料协青早B(O. sativa ssp. indica)为对照品种, 以萎蔫率和死苗率为鉴定指标, 利用江西东乡普通野生稻(O. rufipogon)/协青早B//协青早B构建的回交重组自交系(backcross inbred lines, BILs)群体(BC₁F₉)进行苗期耐冷性鉴定和遗传分析。结果表明, 10°C冷处理7天后, 228个BILs群体的平均萎蔫率为67.4%, 平均死苗率为70.8%。将死苗率≤20%的株系, 在更低温度(8°C昼/5°C夜)下处理5天, 结果显示5243和5335为强耐冷材料, 可用于构建东乡野生稻QTL(quantitative trait loci)近等基因系(near-isogenic lines, NILs)。实验结果显示, 群体萎蔫率和死苗率均呈偏态的连续分布, 暗示东乡野生稻苗期耐冷性表现为质量-数量性状遗传特征, 由主基因-多基因控制。     

Thermal inactivation of alpha-galactosidase from Penicillium canescens

The kinetics and mechanism of thermal inactivation of Penicillium canescens alpha-galactosidase in the temperature range of 55-65 degrees C have been studied. The kinetic scheme of alpha-galactosidase thermal inactivation was proposed which included the reversible dissociation of active hexamers into associating monomers and irreversible denaturation of monomers. The kinetic constants of thermal inactivation have been determined. The effect of enzyme concentration and purification efficiency has been investigated. A possibility of defence of protein molecule from thermal inactivation in the presence of BSA, glycerol, melibiose, raffinose and stachyose is shown.     

Mapping of QTLs associated with cold tolerance during the vegetative stage in rice

Low-temperature stress is an important factor affecting the growth and development of rice (Oryza sativa L.) in temperate and high-elevation areas. Cold stress may cause various seedling injuries, delayed heading and yield reduction due to spikelet sterility. In this study, 181 microsatellite marker loci were used to identify quantitative trait loci (QTLs) associated with cold tolerance at the vegetative stage in 191 recombinant inbred lines (RILs) derived from a cross of a cold-tolerant temperate japonica cultivar (M-202) with a cold-sensitive indica cultivar (IR50). Different temperature regimes were applied in growth chambers on 191 RILs. The temperature regimes imposed in the growth chamber simulated cold-stress injuries at the seedling and late vegetative stages. In this study a major QTL was identified on chromosome 12, designated as qCTS12a, that was closely associated with cold-induced necrosis and wilting tolerance, and accounted for 41% of the phenotypic variation. A number of QTLs with smaller effects were also detected on eight rice chromosomes.