Relationship between autoregulation and nitrate inhibition of nodulation in soybeans

Ten of 11 supernodulating mutants of soybean [ Glycine max (L.) Merr.] cv. Bragg, in which nodulation was far in excess of that in the wild type, showed pronounced tolerance of nodulation to applied nitrate. Mutant nts (nitrate-tolerant symbiosis) 1116 had an intermediate nodulation response and also showed some inhibition by nitrate. Mutant 1029, a revertant of nts382 (an extreme supernodulator), showed a wild-type nodulation pattern and was equally sensitive to nitrate as cv. Bragg. Grafting experiments with cv. Bragg and nts382 indicated that both supernodulation and tolerance of nodulation to nitrate were dependent on shoot factors. Total leaf nitrate reductase (EC 1.6.6.1 and EC 1.6.6.2) activity of the supernodulating mutants was similar to that in cv. Bragg. We conclude from these results that the inhibitory effect of nitrate on nodule initiation and development in soybean depends on an interaction between nitrate and the autoregulation singal. In the supernodulating mutants, the autoregulation signal is either altered or absent and cosequently nodulation in these mutants is not sensitive to nitrate.     

An attempt to elucidate the origin of cultivated soybean via comparison of nucleotide sequences encoding glycinin B4 polypeptide of cultivated soybean,Glycine max,and its presumed wild progenitor,Glycine soja

Summary Nucleotide sequences of cDNAs encoding soybean glycinin B₄ polypeptide were compared for three soybean cultivars and two introductions of wild soybean, G. soja. For three G. max cultivars, only two nucleotide substitutions were found, while G. max and G. soja nucleotide sequences had four substitutions. These data give added proof that G. max originated from G. soja. On the other hand, the time required for the accumulation of four nucleotide substitutions (calculated from the parameters of 11S globulin molecular evolution) appeared to be longer than the duration of the soybean domestication period.     

大豆蛋白编码基因起源与进化

物种基因组成是一个高度动态的进化过程, 其中相对较近起源的种系和物种特异性基因会持续整合到包含古老基因的原始基因网络中。新基因在塑造基因组结构中发挥重要作用, 能提高物种适应性。基因复制和新基因的从头起源是产生新基因及改变基因家族大小的2种方式。目前, 大豆(Glycine max)基因起源时间与进化模式的相互联系很大程度上还未被探索。该研究选择19种具有代表性的被子植物基因组, 分析基因含量动态性与大豆基因起源之间的潜在联系。采用基因出现法, 研究显示约58.7%的大豆基因能追溯到大约1.5亿年前, 同时有21.7%的基因为最近起源的orphan基因。研究结果表明, 与新基因相比, 古老基因受到更强的负选择压并且更加保守。此外, 古老基因的表达水平更高且更可能发生选择性剪切。此外, 具有不同拷贝数的基因在上述特征中也具有明显差异。研究结果有助于认识不同年龄基因的进化模式。     

Nature of proteinase inhibitors released from soybeans during imbibition and germination

Proteinase inhibitors are released to a smaller extent from soybeans which have been pre-equilibrated to an atmosphere of high relative humidity (r.h.) compared to those equilibrated to low r.h. Seeds pre-equilibrated to high r.h. also exhibited better germination. Regardless of the states of seed hydration, both Kunitz and Bowman-Birk soybean trypsin inhibitors are released in parallel with respect to each other and to other proteins at germination times up to 100 hr. After 48 hr of germination, new forms of trypsin inhibitor appear in the leachate which react with anti-Bowman-Birk trypsin inhibitor antibodies. No new forms of Kunitz trypsin inhibitor were observed immunochemically during the first 100 hr of germination.     

Heat shock proteins and effects of heat shock in plants

Soybean seedlings when exposed to a heat shock respond in a manner very similar to that exhibited by cultured cells, and reported earlier [2]. Maximum synthesis of heat shock proteins (HSPs) occurs at 40C. The heat shock response is maintained for a relatively short time under continuous high temperature. After 2.5 hr at 40 C the synthesis of HSPs decreases reaching a very low level by 6 hr. The HSPs synthesized by cultured cells and seedlings are identical and there is a large degree of similarity in HSPs synthesized between the taxonomically widely separated species, soybean and corn. Storage protein synthesis in the developing soybean embryo is not inhibited but is actually stimulated during a heat shock, unlike most other non-HSPs, whose synthesis is greatly reduced. Seedlings respond differently to a gradual increase in temperature than they do a sudden heat shock. There is an upward shift of several degrees in the temperature at which maximum protein synthesis occurs and before it begins to be inhibited. In addition, there appears to be a protection of normal protein synthesis from heat shock inhibition when the temperature increase is gradual. An additional function of the heat shock phenomenon might be the protection of seedlings from death caused by extreme heat stress. The heat shock response appears to have relevance to plants in the field.     

Absorption and fluorescence spectra ofS-quinolylethylated Kunitz soybean trypsin inhibitor

Disulfide bonds in soybean trypsin inhibitor (Kunitz) were simultaneously reduced and alkylated using tri-n-butylphosphine and 2-vinylquinoline at pH 7.6 in 0.11 M Tris-4.4 M urea, 41% ethanol. The resulting S--2-quinolylethylated protein (2-QE-STI) has a new absorption peak at 315–318 nm. Its quinoline fluorescence can be excited above 310 nm independently of intrinsic protein fluorescence. Free 2-quinolylethylcysteine (2-QEC) shows unexpectedly weak fluorescence. Quinoline absorption in 2-QEC and 2-QE-STI changes with pH. The apparentpK values determined spectrophotometrically are near 5 for 2-QEC and 3 for 2-QE-STI. Fluorescence decreased with increasing pH and in the presence of chloride ions. Both structural and charge effects thus appear to influence the absorption and fluorescence of the quinoline group. Corrected fluorescence emission (excited at 316 nm) of neutral 2-QE-STI diluted in 0.1 N H₂SO₄ was directly proportional to concentration in the range 0.4–8 m 2-QEC. The 2-QEC content of the protein derivative determined by UV absorption at pH 1.5 was in agreement with the expected value of four residues per mole. Fluorescence measurements ofS-2-quinolylethylated proteins may be especially useful as a sensitive, specific assay for cyst(e)ine residues.Reference to a company or product name does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of others that may be suitable.Abbreviations used are Mops: 3-(N-morpholino)propanesulfonic acid; STI: soybean trypsin inhibitor (Kunitz); 2-PE-STI:S--2-pyridylethylated STI; 2-QEC:S--(2-quinolylethyl)-l-cysteine; 2-QE-STI:S--2-quinolylethylated STI; TosPheCH₂-trypsin: bovine trypsin treated withp-toluenesulfonyl phenylalanine chloromethyl ketone.     

The accumulation of accessory pigments as a function of chlorophyll a. A comparison of development and genetic control

A comparison is made between pigment accumulation in pigment-deficient genotypes of soybean ( Glycine max ) at any one sampling time (genotype control) and pigment accumulation for any one genotype as a function of development (development control). Plots of accessory chloroplast pigments against chlorophyl a show various linear and non-linear relationships that are similar whether generated by genetic differences or by the development process. These relationships are related to the formation and development of pigment-protein complexes especially the relationship of carotenoids to these complexes.     

Infra-species Variation in Reactions to Hosts in Heterodera glycines Population

Eighteen hosts were inoculated with each of four races of Heterodera glycines. A discriminant function analysis of the reactions of these races to these hosts demonstrated that these races could be separated but not consistently. Then 33 H. glycines populations collected from 13 states and five obtained from Japan were tested on differential hosts. The number of variants discriminated within these 38 populations depended on the number of differentials and the rating system used. When five differentials were used with a (+) or (-) rating system there were six "races," but when 13 differentials were used with a (+) or (-) system there were 25 physiological groups. If an index rating system was used there were 36 groups. Apparently H. glycines is a very variable species and delineation of races varies with criteria chosen.     

Serine protease inhibitors inhibit superoxide production by human basophils stimulated by anti-IgE

Anti-IgE-induced O₂^? production by human basophils was inhibited by potent inactivators of serine proteases. The inhibitory effect of the inhibitor and substrate for chymotrypsin-type protease was much greater than that of those substances for trypsin-type protease. These findings suggest that chymotrypsin-like serine proteases are involved in basophil O₂^? production.     

Effect of polyamines on ethylene production

The polyamines putrescine, cadaverine, spermidine and spermine reduced the amount of ethylene produced by senescing petals of Tradescantia but they did not prevent anthocyanin leakage from these same petals. These polyamines also inhibited auxin-mediated ethylene production by etiolated soybean hypocotyls to less than 7 % of the control. The basic amino acids lysine and histidine reduced the amount of auxin-induced ethylene produced by soybean hypocotyls by ca 50 %. In the hypocotyls, methionine was unable to overcome the inhibition caused by the polyamines. The polyamines spermidine and spermine inhibited ethylene production induced by the application of 1-aminocyclopropane-1-carboxylic acid and they also reduced the endogenous content of this amino acid in the treated tissues.