Levels Of Soluble Carbohydrates Research Articles

Cloning and Characterization of an Annexin Gene from Cynanchum komarovii that Enhances Tolerance to Drought and Fusarium oxysporum in Transgenic Cotton

A novel plant annexin, CkANN, was isolated from Cynanchum komarovii. Sequence analysis showed that CkANN contained four conserved exdonexin fold regions, a putative peroxidase heme binding motif and two S3 clusters. Real-time PCR analysis indicated that the CkANN mRNA was abundant in leaf, flower, root and stem and that its level is highest in leaf and flower. The transcription level of CkANN was increased significantly following stress by salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), NaCl, PEG 6000 (polyethylene glycol) and H2O2. Over-expression of CkANN in transgenic cotton caused a significant increase in tolerance to drought and led to higher levels of proline and soluble carbohydrates compared to wild-type (WT) plants. In response to drought, the transgenic plants also displayed higher total chlorophyll levels and reduced accumulation of thiobarbituric acid-reactive substances (TBARS) compared to WT plants. Furthermore, the transgenic cotton showed enhanced resistance to Fusarium oxysporum via increased total peroxidase activity and induction of the expression of some pathogenesis-related proteins. In conclusion, this study has demonstrated that C. komarovii CkANN is involved in drought tolerance and disease resistance and therefore may contribute significantly to the development of drought- or disease-resistant crops.

AMELIORATIVE EFFECT OF STIGMASTEROL ON THE PRODUCTIVITY OF Vicia faba PLANTS GROWN UNDER SALT STRESS.

The present investigation was carried out to study the effect of post-emergence soil treatment with different salinity levels (0.0, 100, 150 and 200 mM NaCl) on growth, endogenous phytohormones, yield components and some biochemical activities of the yielded seeds of Vicia faba plants. The results indicated that increasing of salinity up to 200 mM showed significant decreases in growth parameters at fruiting stage and yield components. On the other hand, the levels of IAA, GA3 decreased, while ABA level increased with salt stress. Biochemical activities of the yielded seeds such as carbohydrate contents and total protein significantly decreased as compared with non-salinized plant, while salt stress induced the accumulation of the total phenol and proline contents. In addition, the content of Na+ increased significantly under salinity stress, while K+, Ca+2 and P+3 contents were decreased, when compared with those of the control. Application of stigmasterol by seed soaking, counteracted the adverse effects of salinity through inducing significant increases in all growth criteria at fruiting stage, yield components, levels of IAA, GA3, soluble, insoluble and total carbohydrates, total protein concomitantly with decreases in total phenols, proline content and level of ABA as compared with those of the reference plants. Also, treatment with stigmasterol resulted mostly in a decrease of Na+ accumulation concurrently with significant increases of K+, Ca+2, P+3 contents, K+/Na+ and Ca+2/Na+ ratio when compared with those of the reference controls. These results indicate the role of stigmasterol in increasing the tolerance of Vicia faba plants to salt stress. Three prominent types of modifications were observed in the protein patterns of yielded seeds, some proteins were disappeared, other proteins were selectively increased and synthesis of a new set of protein was induced, some of these responses were observed under stigmasterol and salinity, while others were induced by either stigmasterol or salinity.

Free Cyclitol, Soluble Carbohydrate and Protein Contents in Vigna unguiculata and Phaseolus vulgaris Bean Sprouts

Seeds sprouts have been used as a good source of basic nutrients and nutraceutical compounds. The high nutritional value of seeds derives from the deposition of compounds during development. However some of these molecules are used in metabolic processes like germination, which leads to a considerable variation in their concentrations once these events are completed. In this work, we investigate the levels of inositols (myo-inositol, D-pinitol and ononitol), soluble carbohydrates and proteins in cotyledons of Phaseolus vulgaris and Vigna unguiculata sprouts. Sprouting increased myo-inositol and glucose content and reduction of raffinose and ononitol was observed. The protein levels increased in P. vulgaris and decreased in V. unguiculata sprouting. The level of sucrose was maintained in both sprouts. D-Pinitol was detected only in quiescent seeds. Our results suggested that bean sprout is an important source of proteins, sucrose, glucose and myo-inositol. Additionally, bean sprouts have low levels of raffinose, an antinutritional compound.

Physiological, biochemical, and fluorescence parameters of senescing sugar beet leaves in the vegetative phase of growth

The phase of vegetative growth of sugar beet (Beta vulgaris L., single-sprout form) was conditionally subdivided into four periods according to leaf number and size (including already withered leaves): (A) 8 ± 1 weeks after seedling emergence (wase) (5–7 leaves); (B) 11 ± 1 wase (10–12 leaves); (C) 14 wase (13–15 leaves); (D) 15 wase (15–18 leaves). It took each next leaf about 1 week to come into view. In the course of leaf senescence, palisade parenchyma became less ordered; cells, vacuoles, and intercellular spaces expanded; leaf area and thickness increased. Chloroplasts became swollen, starch grains (and later osmiophilic globules) accumulated and degraded. In every growth period, the highest levels of soluble carbohydrates (sCH), chlorophyll (Chl (a + b)), soluble protein, and the highest activities of rubisco and soluble carboanhydrase usually preceded the full leaf expansion. In unfolded leaves at the growth period B, the maximum values of biochemical characteristics were as a rule higher than at the growth periods A and C and especially D. The only exception was Chl (a + b) with its peak level somewhat increased with plant age. Occurrence of peak values of individual characteristics depended on plant growth period. These characteristics started diminishing asynchronously, with a minimum in old operational leaves. Only the sCH content in the leaves at the periods C and D was stable. Changes in quantum yield at PSII and nonphotochemical fluorescence quenching reflected the age-associated differences in biochemical characteristics. The results are discussed in the light of the idea that leaf senescence is a normal stage of development directly related to the changes in source-sink relations. Biochemically, this stage comprises the degradation of temporarily stored products and partial utilization of the breakdown products for maintenance of the growth of newly formed leaves and root.

NAA and STS effects on bract survival time, carbohydrate content, respiration rate and carbohydrate balance of potted Bougainvillea spectabilis Willd.

The aims of this work were to increase knowledge on the physiology of bract abscission in Bougainvillea spectabilis ‘Killie Campbell’ plants with regard to respiration and carbon balance. Using the effects induced by silver shiosulphate (STS) and/or naphthalene acetic acid (NAA, at high concentration: 500 mg L −1) on bract abscission under interior conditions the relationship between bract survival time (longevity) and respiration rate or carbohydrate levels was investigated. Treatments that included NAA significantly reduced bract abscission. Unexpectedly, the higher the levels of bract soluble and total carbohydrates, measured at day 10 postproduction (PP), the higher the abscission of bracts. These results show, for the first time, that abscission can be positively correlated with non-structural carbohydrate levels in the organ that abscises. Bract respiration rate was significantly affected by treatment and PP day. Treatments that had higher bract respiration rates (WATER and STS) also had higher levels of non-structural carbohydrates in the bracts. Bract respiration rate decreased from day 10 to day 17 PP by approximately 50% (average of all treatments) and was negatively correlated with bract survival time. In the carbon balance per gram of bract dry weight, the treatments WATER and STS, showed the largest decrease in the content of total carbohydrates and had the highest consumption of carbohydrates through respiration. These were the bracts therefore that needed to import a higher amount of carbohydrates per gram of bract dry weight. In the carbon balance for the total mass of bracts and adjacent stems in an average plant, the treatments WATER and STS showed the largest decreases in total carbohydrate during postproduction. However, contrary to the results per gram of bract dry weight, the highest total consumption of carbohydrates by respiration was obtained for the NAA and STS + NAA treatments. Thus bracts that last longer have lower individual carbon consumption while, at the plant level, the increased number of remaining bracts causes a higher overall expenditure. Respiration rate has been used as an indicator of flower longevity and this correlation is here extended for the flower + bract system. Plants that had higher bract respiration rates, most probably, had a higher flow of carbohydrates through the bracts (and flowers), which, in the end, was sensed as a higher carbohydrate level.

High temperature limits in vivo pollen tube growth rates by altering diurnal carbohydrate balance in field-grown Gossypium hirsutum pistils

It has recently been reported that high temperature slows in vivo pollen tube growth rates in Gossypium hirsutum pistils under field conditions. Although numerous physical and biochemical pollen–pistil interactions are necessary for in vivo pollen tube growth to occur, studies investigating the influence of heat-induced changes in pistil biochemistry on in vivo pollen tube growth rates are lacking. We hypothesized that high temperature would alter diurnal pistil biochemistry and that pollen tube growth rates would be dependent upon the soluble carbohydrate content of the pistil during pollen tube growth. G. hirsutum seeds were sown on different dates to obtain flowers exposed to contrasting ambient temperatures but at the same developmental stage. Diurnal pistil measurements included carbohydrate balance, glutathione reductase (GR; EC 1.8.1.7), soluble protein, superoxide dismutase (SOD; EC 1.15.1.1), NADPH oxidase (NOX; EC 1.6.3.1), adenosine triphosphate (ATP), and water-soluble calcium. Soluble carbohydrate levels in cotton pistils were as much as 67.5% lower under high temperature conditions (34.6 °C maximum air temperature; August 4, 2009) than under cooler conditions (29.9 °C maximum air temperature; August 14, 2009). Regression analysis revealed that pollen tube growth rates were highly correlated with the soluble carbohydrate content of the pistil during pollen tube growth ( r 2 = 0.932). Higher ambient temperature conditions on August 4 increased GR activity in the pistil only during periods not associated with in vivo pollen tube growth; pistil protein content declined earlier in the day under high temperatures; SOD and NOX were unaffected by either sample date or time of day; pistil ATP and water soluble calcium were unaffected by the warmer temperatures. We conclude that moderate heat stress significantly alters diurnal carbohydrate balance in the pistil and suggest that pollen tube growth rate through the style may be limited by soluble carbohydrate supply in the pistil.

Mobilização de reservas no eixo embrionário e nos cotilédones de sementes de <i>Schizolobium parahyba</i> (Vell.) S. F. Blake durante a germinação

O conhecimento da composição química da semente é de extrema importância para auxiliar o entendimento do comportamento durante a germinação, o armazenamento ou mesmo nos processos metabólicos envolvidos na degradação dessas reservas, que, em última instância, afetam o vigor das sementes. Dessa forma, o objetivo deste trabalho foi estudar as alterações no conteúdo de carboidratos, lipídios e proteínas nos cotilédones e no eixo embrionário, durante a germinação de sementes de Schizolobium parahyba (Vell.) S. F. Blake. Para tanto, as sementes foram colocadas para germinar e retiradas amostras periodicamente para as análises. A porcentagem de germinação foi de 88%, iniciando-se no 9o dia, e a velocidade de germinação foi de 7,7 sementes.dia-1. Dentre os ácidos graxos, o ácido oléico predominou tanto nos cotilédones, quanto no eixo embrionário, com variações durante o período de observação. Os demais tiveram pequena variação e não diferiram de forma expressiva. Os teores de amido e de carboidratos solúveis totais comportaram-se de forma similar nos dois compartimentos com decréscimo ao longo do período de embebição. O teor de proteínas no eixo embrionário, após aumentar em dois dias, decresceu até o 8o dia. Por outro lado, o teor nos cotilédones manteve-se constante nos dois primeiros dias, vindo a cair até o 6o, com aumento no 8o.

Propagation, growth, and carbohydrates of Dendrobium Second Love (Orchidaceae) in vitro as affected by sucrose, light, and dark

In general, plant material grown in vitro has low photosynthetic ability to achieve positive carbon balances. Therefore, a continuous supply of carbohydrates from the culture medium is required, and sucrose has been the most commonly used carbon source. In this paper, we investigate the effects of different sucrose concentrations and the presence and absence of light on the endogenous levels of soluble carbohydrates and starch as well as on the proliferation and growth of Dendrobium Second Love (Orchidaceae) in vitro. The possibility of using etiolated stem segments as a means for micropropagating this hybrid was also verified. The results obtained indicated that the presence and absence of light and the sucrose concentrations used influenced the amounts of soluble carbohydrates and starch and the proliferation of D. Second Love shoots and roots. An increase in sucrose concentration caused a progressive increase in the amounts of total carbohydrates and starch. Under both light conditions, sucrose was the main sugar found in the shoots followed by glucose and fructose. The addition of sucrose to the culture medium up to 2% and 4% was advantageous to the number of shoots produced per explant and the root longitudinal growth in the presence and absence of light, respectively. Shoot and root dry matter and the number of roots formed per explant increased as sucrose concentration was raised up to 6% in both light treatments. The use of dark-grown shoot segments proved to be a useful and reliable alternative for the micropropagation of this hybrid.

Effects of maturity stage, wilting and acid treatment on crude protein fractions and chemical composition of whole crop pea silages ( Pisum sativum L.)

In order to determine if maturity stage, and wilting or acid treatment, change the crude protein (CP) fraction distribution (determined according to the Cornell Net Carbohydrate and Protein System) of whole crop pea silages, a pea with variegated flowers ( Pisum sativum ssp. arvense L., cv Timo) was compared to a white-flowered, semi-leafless pea ( P. sativum ssp. hortense L, cv Capella). Herbage was harvested at three maturity stages being: pod set, pod swell and full pod, and either acid-treated or wilted. Timo was acid-treated using 4 (acid4), 6 (acid6) or 8 (acid8) L/tonne fresh matter (FM) with a 2:1 mixture of formic and propionic acid, or wilted to a dry matter (DM) content of about 400 g/kg. Capella was treated with acid6 or wilted. Herbage was ensiled for 103 days in 10 kg laboratory silos. Despite differences in wilting conditions, all wilted herbages had similar protein fraction distributions. In the Capella silages the soluble CP content was lower in the later maturity stages, but this was not the case in the Timo silages. The amount of acid added only affected the B1 CP fraction content, which decreased with increasing acid. At pod set and pod swell for Timo, and at pod set for Capella, the direct-harvested herbages were difficult to ensile because of the high buffering capacity and low level of water soluble carbohydrates. Wilting improved ensilability. Acid treatment reduced proteolysis, but crops with DM contents below 150 g/kg must be acid treated with at least 6 L/tonne FM to ensure stable fermentation. Timo silages were more prone to malfermentation, probably caused by lodging, which made Capella the preferred cultivar for producing pea silages harvested at the pod swell stage or later. Proteolysis and the amount of soluble CP in the silage were lower in later maturity stages in the Capella, but not the Timo, cultivar.

Both leaf properties and microbe-microbe interactions influence within-species variation in bacterial population diversity and structure in the lettuce (Lactuca Species) phyllosphere.

Morphological and chemical differences between plant genera influence phyllosphere microbial populations, but the factors driving within-species variation in phyllosphere populations are poorly understood. Twenty-six lettuce accessions were used to investigate factors controlling within-species variation in phyllosphere bacterial populations. Morphological and physiochemical characteristics of the plants were compared, and bacterial community structure and diversity were investigated using terminal restriction fragment length polymorphism (T-RFLP) profiling and 16S rRNA gene clone libraries. Plant morphology and levels of soluble carbohydrates, calcium, and phenolic compounds (which have long been associated with plant responses to biotic stress) were found to significantly influence bacterial community structure. Clone libraries from three representative accessions were found to be significantly different in terms of both sequence differences and the bacterial genera represented. All three libraries were dominated by Pseudomonas species and the Enterobacteriaceae family. Significant differences in the relative proportions of genera in the Enterobacteriaceae were detected between lettuce accessions. Two such genera (Erwinia and Enterobacter) showed significant variation between the accessions and revealed microbe-microbe interactions. We conclude that both leaf surface properties and microbial interactions are important in determining the structure and diversity of the phyllosphere bacterial community.

Improvement of Fermentation Quality of Rice Straw Silage by Application of a Bacterial Inoculant and Glucose

The improvement of the fermentation quality of rice straw silage by application of lactic acid bacteria (LAB) and glucose was investigated in this study. Sixteen rice varieties were harvested at the maturity stage and the rice straw was ensiled with LAB inoculant (1×10 5 cfu/g of fresh weight) and glucose (2% of fresh weight). Inoculation with LAB improved the fermentation as reflected in reductions in pH, acetic acid (by 3.7 to 78.3%), butyric acid (by -6.0 to 100.0%) and ammonia nitrogen (by 1.0 to 71.7%) concentrations, and increases in lactic acid (by 43.9 to 282.9%) and crude protein concentrations compared with the control. Application of LAB plus glucose was more effective in improving fermentation quality than LAB alone. The variety of rice straw which contained relatively high levels of water soluble carbohydrates (WSC) tended to obtain better fermentation quality. The results suggested that LAB application and selection of rice varieties whose straw contained high levels of WSC were effective in improvement of the fermentation quality of rice straw silage.

Salinity-induced Physiological Modification in the Callus from Halophyte Nitraria tangutorum Bobr.

Little is known about the physiological adaptation mechanisms of the desert halophyte Nitraria tangutorum Bobr. to the environment. In this study, callus from Nitraria tangutorum Bobr. was used to investigate physiological responses to salinity and the regulatory function of nitric oxide (NO) on catalase (CAT) activity. Increased dry weight and soluble proteins were observed in the callus exposed to lower salinity (50 and 100 mM NaCl), whereas 200 mM NaCl led to significant decreases of these two growth parameters, and the levels of proline and soluble carbohydrates also were enhanced under NaCl treatment. In addition, short-term stress from 50 mM NaCl and the application of lower sodium nitroprusside (SNP, a NO donor) concentration resulted in decreased levels of malondialdehyde (MDA). In contrast, higher concentrations of NaCl and SNP induced significant oxidative damage in Nitraria tangutorum Bobr. callus. Analysis based on the fluorescent probe DAF-FM DA revealed that NaCl and SNP treatment led to enhanced levels of NO in the callus cells. Moreover, the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) reduced endogenous NO concentrations and abolished the enhancement in dry weight and the decrease in MDA level under 50-mM-NaCl treatment. CAT activity increased under salt stress, and the 50-mM-NaCl effect was alleviated by treatment with c-PTIO or the nitric oxide synthase inhibitor Nω-nitro-l-arginine. We suggest that Nitraria tangutorum Bobr. callus exhibited tolerance to lower-salinity stress. We also showed that increased NO generation in response to salinity might be associated with regulation of growth, protection against oxidative damage, and excitation of CAT activity in Nitraria tangutorum Bobr. callus under salt stress.

Influence of zinc on soluble carbohydrate and free amino acid levels in rapeseed plants regenerated in vitro in the presence of zinc

To gain more insight into the impact of zinc on the primary metabolites in rapeseed, plants were regenerated in vitro in the presence of zinc (0.1–1 mM), acclimatized, transferred to a greenhouse, and treated with 2 mM ZnSO4. The main metabolites, including soluble carbohydrates and free amino acids, were analyzed by nuclear magnetic resonance spectroscopy, and further confirmed by spectrophotometry and enzymatic analyses. Exposure of these greenhouse-grown plants to ZnSO4 led to both a significant rise of the total amino acid level and an increase of proline accumulation in the different tissues. Moreover, the control plants, regenerated without zinc stress, exhibited a significant reduction of soluble carbohydrate levels, whereas the plants derived from Zn-treated regenerants exhibited significantly higher levels of both glucose and sucrose. These levels increased proportionally with the Zn concentration in the regeneration step.

Effect of salinity on chlorophyll and carbohydrate contents of Sesbania grandiflora seedlings

The effect of NaCl salinity concentrations (viz. 10, 20, 30, 40 and 50 mM NaCl) on the contents of chlorophyll a and b and carbohydrate (soluble and insoluble) of Sesbania grandiflora (L) Pers. seedlings were investigated. The investigation showed significant positive influence of higher salinity concentrations on the parameters. The elevated levels of the total soluble and insoluble carbohydrates in the shoot and root are considered to be playing an important role in the osmotic adjustment.

Photosynthetic Activity and Soluble Carbohydrate Content Induced by the Cold Acclimation Affect Frost Tolerance and Resistance to Microdochium nivale of Androgenic Festulolium Genotypes

AbstractThe aim of the experiment was to verify whether changes in photosynthetic activity measured by means of chlorophyll fluorescence techniques and soluble carbohydrate level induced during pre‐hardening and cold acclimation in androgenic forms of Festulolium are related to their winter hardiness and pathogen resistance. The study was performed on six androgenic genotypes of Festulolium, which differ in their degrees of winter hardiness. The chlorophyll fluorescence parameters and sugar content were measured in the control plants, pre‐hardened at 12 °C and cold‐acclimated at 2 °C. Cold acclimation at 2 °C, preceded by pre‐hardening at 12 °C, induced a decline in maximum PSII quantum efficiency (Fv/Fm) and in non‐photochemical quenching (NPQ). Exposure to 2 °C also resulted in reduced efficiency of energy conversion in photochemical processes (qp). The soluble carbohydrate amount increased in the susceptible genotypes and was associated with a decline in NPQ and current quantum yield of PSII (φPSII). In resistant plants, a decrease in the sugar content was observed, which could be explained by their consumption in metabolic processes initiated during cold acclimation. The changes in sugar content were associated with a decline in NPQ and qp.

Interação entre Colletotrichum gloeosporioides e ecótipos de pinha

A produção brasileira de pinha (Annona squamosa L.) predomina no Nordeste, sendo afetada pela antracnose causada por Colletotrichum gloeosporioides. Este estudo avaliou: 1) as taxas de crescimento micelial e conidiação, dimensões de conídios e produção de amilase, xilanase, pectinases e protease por isolado desse fungo de lesões de abacate (Persea americana Mill), em diferentes meios; 2) as porcentagens de germinação e formação de apressórios do mesmo sobre folhas jovens de pinha; 3) as alterações in vivo nos teores de proteínas, fenóis e carboidratos solúveis totais, antes e após a inoculação. Folhas jovens de plântulas de dois ecótipos de pinha (PI e CT) foram destacadas, submetidas à inoculação e incubadas ou para sua extração (0 e 36 horas após), ou para seu clareamento (0, 12, 18, 24, 30, 36, 42 e 46 horas após), coloração e análise ao microscópio. Particionou-se cada extrato contra hexano, e a fração polar foi concentrada e resolubilizada para determinação dos parâmetros bioquímicos mencionados. Verificou-se maior esporulação do isolado fúngico em meio Mathur, e este produziu todas as enzimas ensaiadas in vitro. In vivo, este foi mais agressivo ao ecótipo PI, mas verificou-se ca. de 80% de germinação e 50% de formação de apressórios após 24 e 30 horas de incubação respectivamente sobre os ecótipos PI e CT. Os teores de proteínas, glicídeos redutores e fenóis totais dos extratos de CT foram mais elevados 36 horas após a inoculação, enquanto apenas uma ligeira elevação no conteúdo de fenóis foi constatada nos extratos de PI.

Partitioning of assimilates to deeper roots is associated with cooler canopies and increased yield under drought in wheat

Dehydration avoidance through cooler canopy temperature (CT) has been shown to explain over 60% yield variation in a random progeny derived from a Seri/Babax cross. A near ‘isomorphic’ subset of Seri/Babax progeny and parents encompassing a restricted range of height and phenology were used for detailed characterisation of drought-adaptive trait expression under contrasting water regimes. Under drought, five of the six progeny out yielded the best parent Babax by up to 35%. The main physiological attributes associated with drought adaptation were increased root dry weight at depth, transpiration rate – evidenced by grain carbon isotope discrimination (Δ13C) – grain filling duration and decreased CT during grain filling. Furthermore, increased root mass at depth was associated with reduced levels of stem water soluble carbohydrates (WSC) when comparing genotypes. It is concluded that differences in rooting depth expressed among iso-morphic wheat sister lines explains superior adaptation to drought. These effects can be detected in season using remote sensing. In addition, the data suggest that accumulation of stem carbohydrates and deep rooting may be two alternative strategies for adapting to drought stress, the latter being beneficial where water is available at depth.

Effects of Light Intensity, Number of Florets, and Water Stress on Quality and Soluble Carbohydrate Contents of Potted Carnation

The indoor display life of potted carnations ‘Annemarie’ is limited to 12 days because of its low flowering ability under low-light conditions (15 μmol·m−2·s−1 PPFD, 20°C). When commercially grown potted carnations were transferred to indoor (low-light) conditions, dry weight and total soluble carbohydrates (TSC) decreased during the first 6 days after transfer (DAT), remained constant until 10 DAT, and then increased at 14 DAT. Glucose, fructose, and sucrose contents decreased markedly during the first 6 DAT and then gradually decreased. Pinitol content was unchanged until 10 DAT and then slightly increased at 14 DAT. After 30 days in indoor conditions, the concentrations of fructose, glucose, and sucrose in leaves declined to barely detectable levels, while the pinitol content was unchanged. By the end of 30 days, pinitol accounted for 79% of TSC. In another experiment, potted carnations were grown under water-stress conditions (0.21 m3 water/m3 soil) for 14 days. Compared with plants grown under ample water conditions (0.41 m3water/m3 soil), water-stressed plants showed lower water potential and increased the contents of pinitol, glucose, and TSC in the leaves; however, the differences in water potential and soluble carbohydrate level disappeared after plants were supplied with ample water. To optimize flowering, we thinned the number of florets to 20, 50, or 80 per plant. Compared with plants with 50 or 80 florets, plants with 20 florets per plant showed higher chlorophyll fluorescence ratio (Fv/Fm) in their leaves and had more flowers per plant. In addition, we evaluated the effects of low-light conditions (15 μmol·m−2·s−1) and high-light conditions (alternate cycles of 15 μmol·m−2·s−1 for 2 days and 150 μmol·m−2·s−1 for 1 day) on flowering. At 20 DAT, flowers in the high-light treatment showed higher TSC than those in the low-light treatment; however, levels of pinitol were significantly higher in plants grown under low-light conditions. These results suggested that thinning flower buds and growing plants under high-light conditions could alleviate the carbohydrate shortage that occurs in indoor conditions, and could improve the quality and display life of potted carnations. We discuss the roles of pinitol in carnation plants under stress conditions.

Distribution of thermogenic activity in floral tissues of Nelumbo nucifera

Thermogenesis in Nelumbo nucifera (Gaertn.) has been known to scientists for many years; however, the extent of heating by different floral parts remains unclear. We present evidence that the receptacle, stamens and petals produce heat independently, and that the source of heating in these tissues is most likely the alternative oxidase (AOX). The temperatures of the receptacle, petals and stamens were significantly higher than non-thermogenic leaf tissue. After removal from the pedicel, the receptacle retained the most heat (8.1 ± 1.9°C above non-thermogenic tissue temperature) and the petals the least (2.8 ± 4.2°C), with the stamens intermediate. High AOX protein levels and flux through the AOX pathway (in all tissues) during the thermogenic period are consistent with AOX being the mechanism used for thermogenesis. Lipids and carbohydrates were investigated as possible substrates for thermogenesis. There was little change in total lipids during floral development; however, soluble carbohydrate levels decreased by 70% with the onset of thermogenesis. These sugars may fuel thermogenesis in the stamens. The localisation of AOX protein in the various floral parts and the evolutionary significance of its heating role are discussed.

Overexpression of the soybean GmERF3 gene, an AP2/ERF type transcription factor for increased tolerances to salt, drought, and diseases in transgenic tobacco

A new member of the AP2/ERF transcription factor family, GmERF3, was isolated from soybean. Sequence analysis showed that GmERF3 contained an AP2/ERF domain of 58 amino acids and two putative nuclear localization signal (NLS) domains. It belonged to a group IV protein in the ERF (ethylene response factor) subfamily as typified by a conserved N-terminal motif [MCGGAI(I/L)]. Expression of GmERF3 was induced by treatments with high salinity, drought, abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and soybean mosaic virus (SMV), whereas there was no significant GmERF3 mRNA accumulation under cold stress treatment. GmERF3 could bind to the GCC box and DRE/CRT element, and was targeted to the nucleus when transiently expressed in onion epidermal cells. The GmERF3 protein fused to the GAL4 DNA-binding domain to activate transcription of reporter genes in yeast. Ectopic expression of the GmERF3 gene in transgenic tobacco plants induced the expression of some PR genes and enhanced resistance against infection by Ralstonia solanacearum, Alternaria alternata, and tobacco mosaic virus (TMV), and gave tolerance to high salinity and dehydration stresses. Furthermore, overexpression of GmERF3 in transgenic tobacco led to higher levels of free proline and soluble carbohydrates compared to wild-type plants under drought conditions. The overall results suggested that GmERF3 as an AP2/ERF transcription factor may play dual roles in response to biotic and abiotic stresses in plants.