The growth of soybean under free air [CO<Subscript>2</Subscript>] enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity

Down-regulation of light-saturated photosynthesis (A_sat) at elevated atmospheric CO₂ concentration, [CO₂], has been demonstrated for many C₃ species and is often associated with inability to utilize additional photosynthate and/or nitrogen limitation. In soybean, a nitrogen-fixing species, both limitations are less likely than in crops lacking an N-fixing symbiont. Prior studies have used controlled environment or field enclosures where the artificial environment can modify responses to [CO₂]. A soybean free air [CO₂] enrichment (FACE) facility has provided the first opportunity to analyze the effects of elevated [CO₂] on photosynthesis under fully open-air conditions. Potential ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation (V_c,max) and electron transport through photosystem II (J_max) were determined from the responses of A_sat to intercellular [CO₂] (C_i) throughout two growing seasons. Mesophyll conductance to CO₂ (g_m) was determined from the responses of A_sat and whole chain electron transport (J) to light. Elevated [CO₂] increased A_sat by 15–20% even though there was a small, statistically significant, decrease in V_c,max. This differs from previous studies in that V_c,max/J_max decreased, inferring a shift in resource investment away from Rubisco. This raised the C_i at which the transition from Rubisco-limited to ribulose-1,5-bisphosphate regeneration-limited photosynthesis occurred. The decrease in V_c,max was not the result of a change in g_m, which was unchanged by elevated [CO₂]. This first analysis of limitations to soybean photosynthesis under fully open-air conditions reveals important differences to prior studies that have used enclosures to elevate [CO₂], most significantly a smaller response of A_sat and an apparent shift in resources away from Rubisco relative to capacity for electron transport.Abbreviations FACE Free air [CO₂] enrichment - Rubisco Ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP Ribulose-1,5-bisphosphate - SoyFACE Soybean free air [CO₂] enrichment - VPD Vapor pressure deficit     

Entity evidence for differentiation between Tia and Tib types of soybean Kunitz trypsin inhibitor: detection of a novel transitional variant type between Tia and Tib in wild soybean (Glycine soja Sieb. & Zucc.)

Soybean Kunit trypsin inhibitor (SKTI) has several polymorphic types. Of these SKTI, there are large differences of nine amino acid substitutions between Tia and Tib. So far no transitional type between them has been found. A novel transitional intermediate variant between Tia and Tib was detected in 11 lines from 720 Japanese wild soybeans (Glycine soja Sieb. & Zucc.). This variant showed identical electrophoretic mobility to Tib in the Davis system polyacrylamide gel electrophoresis (PAGE), but higher electric points than other SKTI proteins (Tia, Tib, Tic) in isoelectric focusing PAGE. The genetic analysis of SKTI in F₂ seeds from a cross between the novel variant type and Tib showed that this variant type is inherited as codominant alleles in a multiple allelic system at an SKTI locus. This variant also showed inhibitory activity to trypsin. We propose the genetic symbol Ti b ⁱ⁵ for this novel variant. The sequence analysis of Tib ⁱ⁵ revealed that six nucleotides were different between Tib ⁱ⁵ and Tia, and the nucleotides of these mutated positions were identical to Tib. This causes substitution of five amino acids at the residue position 62 (Tyr→Phe), 74 (Ser→Arg), 114 (Met→Val), 120 (Leu→Ile) and 137 (Pro→Thr). These substitutive amino acids are completely in accord with the amino acids of Tib, showing that Tib ⁱ⁵ is an intermediate between Tia and Tib types. Tib ⁱ⁵ type is widely distributed throughout seven separate areas from northeast to southwest Japan with a 1.5% frequency of total materials examined. This indicated that Tib ⁱ⁵ type did not originate from a recent mutation event, but had spread in wild soybean from ancient times.     

Complete Chloroplast Genome Sequence of <Emphasis Type="Italic">Glycine max</Emphasis> and Comparative Analyses with other Legume Genomes

Lack of complete chloroplast genome sequences is still one of the major limitations to extending chloroplast genetic engineering technology to useful crops. Therefore, we sequenced the soybean chloroplast genome and compared it to the other completely sequenced legumes, Lotus and Medicago. The chloroplast genome of Glycine is 152,218 basepairs (bp) in length, including a pair of inverted repeats of 25,574 bp of identical sequence separated by a small single copy region of 17,895 bp and a large single copy region of 83,175 bp. The genome contains 111 unique genes, and 19 of these are duplicated in the inverted repeat (IR). Comparisons of Glycine, Lotus and Medicago confirm the organization of legume chloroplast genomes based on previous studies. Gene content of the three legumes is nearly identical. The rpl22 gene is missing from all three legumes, and Medicago is missing rps16 and one copy of the IR. Gene order in Glycine, Lotus, and Medicago differs from the usual gene order for angiosperm chloroplast genomes by the presence of a single, large inversion of 51 kilobases (kb). Detailed analyses of repeated sequences indicate that many of the Glycine repeats that are located in the intergenic spacer regions and introns occur in the same location in the other legumes and in Arabidopsis, suggesting that they may play some functional role. The presence of small repeats of psbA and rbcL in legumes that have lost one copy of the IR indicate that this loss has only occurred once during the evolutionary history of legumes.     

Debittering effect of Monascus carboxypeptidase during the hydrolysis of soybean protein

The actions of pepsin and the admixture of pepsin and Monascus pilosus carboxypeptidase 1 (MpiCP-1) on the hydrolysis of soybean protein were studied. The results showed that the pepsin hydrolyzate of soybean protein was much more bitter and contained relatively smaller amounts of total free amino acids than the hydrolyzate obtained with the admixture of pepsin and MpiCP-1. In addition, hydrophilic and hydrophobic amino acids were present in almost equal proportions in the pepsin hydrolyzate, while mainly hydrophobic amino acids made up the hydrolyzate obtained with the admixture of pepsin and MpiCP-1. These results suggest that MpiCP-1 suppresses and reverses the development of the bitterness taste that results from the pepsin hydrolysis of soybean protein by releasing mainly hydrophobic amino acids from the C-termini of the bitter components.     

PM2, a group 3 LEA protein from soybean, and its 22-mer repeating region confer salt tolerance in Escherichia coli

To have knowledge of the effect of soybean PM2 protein in protecting dehydrated cells and its functional region, PM2 cDNA was isolated from soybean immature seeds. The recombinants expressing full-length PM2, truncated polypeptides of PM2A (aa 1-262) or PM2B (aa 129-262, 22-mer repeating region), or artificial polypeptide PM2C (duplication of 22-mer repeating region) were constructed. By using SDS-PAGE and mass spectrometry approaches, these fusion polypeptides were identified and proved to be hydrophilic and heat-stable. Spot assays of BL/PM2 and BL/pET28 (as control) showed that protein PM2 increased salt tolerance (500 mM NaCl or 500 mM KCl) of Escherichia coli, rather than osmotic tolerance (1100 mM sorbitol). In addition, comparing the survival ratios of the transformants under 500 mM NaCl or 500 mM KCl stresses, the results showed that: (1) the survival ratios of BL/PM2 and BL/PM2B were quite similar, both showing much higher values than those of BL/pET28. (2) The survival ratios of BL/PM2C were much higher than those of BL/PM2, BL/PM2A, and BL/PM2B. This provides the first experimental evidence that PM2 polypeptide enhances salt tolerance of E. coli cells, and the 22-mer repeat region is an important functional region.     

大豆类受体蛋白激酶基因GmRLCK的克隆及初步分析

植物类受体蛋白激酶(receptor-likeproteinkinase,RLK)在高等植物生长发育和环境刺激的信号传导中起着重要的作用。本文报告了一个新的大豆类受体蛋白激酶基因的全长cDNA克隆及对其基因结构和功能的初步分析。研究表明该基因序列编码的蛋白包含一个跨膜域、一个具有丝氨酸/苏氨酸激酶活性的胞内域和一个缺少N-末端信号肽的胞外域。采用生物信息学方法分析表明,该基因与一些拟南芥菜类受体蛋白激酶基因具有很高的相似性,这些激酶N-末端都缺少信号序列,属于植物胞质类受体激酶(receptor-likecytoplasmickinase,RLCK)亚家族。因此命名该大豆基因为GmRLCK(GenBankAccessionNo.AY687390)。对GmRLCK激酶域中磷酸化可能性较高的位点进行了预测。RT-PCR的结果表明,GmRLCK在大豆子叶、根、花以及豆荚中都有较高的表达,而在胚根、茎和成熟叶片中的表达相对较弱。进化分析表明GmRLCK与一些衰老相关的植物类受体蛋白激酶具有较近的亲缘关系。     

酸雨对大豆幼苗根系形态及矿质营养的影响

目的研究酸雨对大豆幼苗根系形态及矿质营养代谢的影响。方法采用营养液培养的方法,研究不同pH 2.5、3.0、3.5、4.0和4.5模拟酸雨对大豆幼苗根系形态、根系活力及根系硝酸还原酶活性的影响。结果酸雨pH≤3.0时对大豆幼苗根系形态及根系活力的作用明显,呈现抑制作用;根系硝酸还原酶活性先随pH(≥3.5)的降低而缓慢升高,之后迅速降低。结论酸雨对大豆幼苗根系生长及矿质营养代谢有抑制作用,且pH=3.0是酸雨对大豆幼苗根系形态及矿质营养影响的关键点。     

Carboxylesterase activities toward pesticide esters in crops and weeds

Proteins were extracted from maize, rice, sorghum, soybean, flax and lucerne; the weeds Abutilon theophrasti, Echinochloa crus-galli, Phalaris canariensis, Setaria faberii, Setaria viridis, Sorghum halepense and the model plant Arabidopsis thaliana and assayed for carboxylesterase activity toward a range of xenobiotics. These included the pro-herbicidal esters clodinafop-propargyl, fenoxaprop-ethyl, fenthioprop-ethyl, methyl-2,4-dichlorophenoxyacetic acid (2,4-d-methyl), bromoxynil-octanoate, the herbicide-safener cloquintocet-mexyl and the pyrethroid insecticide permethrin. Highest activities were recorded with alpha-naphthyl acetate and methylumbelliferyl acetate. Esters of p-nitrophenol were also readily hydrolysed, with turnover declining as the chain length of the acyl component increased. Activities determined with model substrates were much higher than those observed with pesticide esters and were of limited value in predicting the relative rates of hydrolysis of the crop protection agents. Substrate preferences with the herbicides were typically 2,4-d-methyl>clodinafop-propargyl>fenthioprop-ethyl, fenoxaprop-ethyl and bromoxynil-octanoate. Isoelectric focussing in conjunction with staining for esterase activity using alpha-naphthyl acetate as substrate confirmed the presence of multiple carboxylesterase isoenzymes in each plant, with major qualitative differences observed between species. The presence of serine hydrolases among the resolved isoenzymes was confirmed through their selective inhibition by the organophosphate insecticide paraoxon. Our studies identify potentially exploitable differences between crops and weeds in their ability to bioactivate herbicides by enzymic hydrolysis and also highlight the usefulness of Arabidopsis as a plant model to study xenobiotic biotransformation.     

Steroidal saponins from roots of Asparagus officinalis

Sarsasapogenin M (1) and sarsasapogenin N (2), two new oligospirostanosides with a unique aglycone moiety, (25S)-5beta-spirostan-3beta, 17alpha-diol, along with seven known compounds (25S)-5beta-spirostan-3beta-ol-3-O-beta-d-glucopyranosyl-(1,2)-[beta-d-xylopyranosyl-(1,4)]-beta-d-glucopyranoside (3), (25S)-5beta-spirostan-3beta-ol-3-O-beta-d-glucopyranosyl-(1,2)-beta-d-glucopyranoside (4), (25S)-5beta-spirostan-3beta-ol-3-O-alpha-l-rhamnopyranosyl-(1,2)-[alpha-l-rhamnopyranosyl-(1,4)]-beta-d-glucopyranoside (5), (25S)26-O-beta-d-glucopyranosyl-5beta-furost-20 (22)-ene-3beta,26-diol-3-O-beta-d-glucopyranosyl-(1,2)-beta-d-glucopyranoside (6), yamogenin (7), beta-sitosterol (8), and sitosterol-beta-d-glucoside (9) were isolated from the roots of Asparagus officinalis L. Their structures were determined by spectral analysis, including extensive 1D and 2D NMR experiments.     

Citric acid improves growth performance and phosphorus digestibility in Beluga (Huso huso) fed diets where soybean meal partly replaced fish meal

A 2 × 3 factorial experiment was conducted to evaluate the effect of partial substitution of dietary fish meal with soybean meal and citric acid (CA) supplementation on growth, food utilization, muscle composition and nutrient digestibility of Beluga, Huso huso. Three isonitrogenic and isoenergetic diets, as SBM₁ (soybean meal protein (SBP):fishmeal protein (FP) = 1:3), SBM₂ (SBP:FP = 2:3) and SBM₃ (SBP:FP = 1:1) containing two levels of CA (0 and 30 g kg⁻¹) were fed to triplicate groups of fish for 8 weeks. The results revealed that adding CA increased (P<0.05) the weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) and decreased (P<0.05) food conversion rate (FCR) whereas partial substitution of fishmeal with soybean meal decreased (P<0.05) growth performance. Partial replacement of fishmeal with SBM (P=0.021) as well as CA supplementation (P=0.019) and their interaction (P<0.001) affected hepatosomatic index (HSI). No differences (P>0.05) were observed for viscerosomatic index (VSI) among treatments (P>0.05). No differences (P>0.05) were detected in moisture, protein of muscle sample among treatments, but lipid content was reduced (P<0.05) while ash content increased (P=0.035) by CA. Soybean meal decreased (P<0.05) nutrient digestibility, whereas CA improved apparent protein and phosphorus (P) digestibility (P=0.011 and P<0.001 respectively). No interaction (P<0.05) between levels of SBM and CA was found on these parameters. Results of the present study indicate that Beluga has a limited ability to utilize SBM as a protein source in practical diets whereas CA can improve growth and nutrient utilization in Beluga.