Multilocus Sequence Analysis of Root Nodule Bacteria Associated with <i>Lupinus</i>spp. and <i>Glycine max</i>

Lupinus is known to form endophytic associations with both nodulating and non-nodulating bacteria. In this study, multilocus sequence analysis (MLSA) was used to analyze phylogenetic relationships among root nodule bacteria associated with Lupinus and soybean. Out of 17 bacterial strains analyzed, 13 strains isolated from root nodules of Lupinus spp. were obtained from the National Rhizobium Germplasm Resource Collection, USDA. Additionally, two strains of root-nodule bacteria isolated each from native lupinus and domestic soybean were examined. Sequences of the 16S rRNA gene and three house-keeping genes (atpD, dnaK and glnII) were used. All the reference genes were retrieved from the existing complete genome sequences only. The clustering of 12 of the strains was consistent among single and concatenated gene trees, but not USDA strains 3044, 3048, 3504, 3715, and 3060. According to the concatenated phylogeny, we suggest that USDA 3040, 3042, 3044, 3048, 3051, 3060, 3504, 3709 and 3715 are Bradyrhizobium, USDA 3063 and 3717 are Mesorhizobium, USDA 3043 is Burkholderia and USDA 3057a is Microvirga. The two strains isolated from native lupines in this study are Burkholderia and Rhizobium, whereas the two from domestic soybean are Bradyrhizobium. This study emphasizes the robustness of MLSA, the diversity of bacterial species that are capable of nodulating lupine and the substantial capability of Burkholderia spp. to colonize lupine root nodules.

Lupinus microcarpus Growing in Arsenic—Agricultural Soils from Chile: Toxic Effects and It Potential Use as Phytoremediator Plant

Arsenic (As) is the most important contaminant of the environment in northern Chile. The purpose of the present work is to study As-toxicity symptoms on Lupino microcarpus (lupine), an annual legume plant that constitutes part of the desert community of the pre-Andean area of the Antofagasta Region, Chile. This plant species is cultivated in As-agricultural soil collected from Chiu Chiu (northern Chile) which is classified as arid soils. Control soil (0 - 20 cm depth) is collected from an area located in the central zone of Chile, which is classified as molli soil. The main physic-chemical characteristics of As-soil and the control soil are determined. Eighteen plastic pots of 1.6 L (fifteen for experimental and three for control) are filled with As-soil and control soil treatments. Two plants are cultivated in each pot and then separated leaves and roots for As-analysis. Visual As-toxicity symptoms such as foliar chlorosis, necrosis of the leaf tips and margins, leaf wilting and stunted are determined. Total As concentrations in soils where lupine is cultivated, reach levels between 5.3 - 14.2 mg·kg-1 d.w. (control soil As-level: 3.1 mg·kg-1). Roots show higher As-concentration than leaves, both experimental plants as control plants (2.28 - 9.1 mg·kg-1 d.w., and 0.76 mg·kg-1 d.w., respectively) and low values of transport index (TI) (0.16 - 0.34). All of visual As-toxicity symptoms determined is showed by lupin cultivated in As-agricultural soils. Neither control lupin plant suffers any toxicity symptoms. The results indicate that lupine plants do not resist contamination and accumulated higher levels of As in roots. Lupine can be used in the phytostabilisation of As immobilizing it by microbial activity in agricultural soil.

Root Cluster Formation and Citrate Exudation of White Lupin （Lupinus albus L.） as Related to Phosphorus Availability

Abstract: A split-root system was used to investigate whether the external or internal P concentration controls root cluster formation and citrate exudation in white lupin (Lupinus albus L.) grown under controlled conditions. In spite of low P concentrations in the shoots and roots of the -P plant, its dry weight was not reduced compared with the +P plant. Supplying external P (0.25 mmol/L) to one root half resulted in an increase in P concentration not only in the shoot, but also in the P-deprived root half, indicating P cycling within the plants. Omitting P from both split-root pots stimulated root cluster formation in both root halves, whereas P supply to one root half stimulated root cluster formation at the beginning of the treatment. Neither P supply to just one root half continuously nor resupply of P to one root half after 19 d of P starvation inhibited root cluster formation on the P-deprived side, although the concentration of P in this root half and shoot increased markedly. The results indicate that root cluster formation in L. albus is controlled by both shoot and root P concentrations. The rates of citrate exudation by both root halves with P deficiency were higher than those of the one root half supplied with P only. In the treatment with one root half supplied with P, the rates of citrate exudation by either the P-supplied or -deprived root halves were almost the same, regardless of P concentration in the roots. The results suggest that internal P concentration controls root cluster formation and citrate exudation in white lupin, but these processes may be regulated by different mechanisms.

超声波处理对羽扇豆种子活力及生理特性的影响

采用超声波处理羽扇豆(Lupinus micranthus Guss.)种子,对羽扇豆种子的发芽势、发芽率、活力指数、种子浸出液的相对电导率和幼苗的超氧化物歧化酶(SOD)活性、可溶性蛋白含量、丙二醛(MDA)含量等进行了测定。结果表明,经过超声波处理的羽扇豆种子的发芽势、发芽率都得到了提高,以20 min的处理时间为最佳;处理后提高了羽扇豆幼苗的SOD活性和可溶性蛋白含量,降低了幼苗MDA含量和种子浸出液的相对电导率,提高了种子活力。说明羽扇豆种子萌发之前采用适宜的短时间超声波处理,不仅能促进萌发,还能促进其抗氧化能力的提高。

羽扇豆及其应用价值和栽培

为了促进羽扇豆在我国的引种驯化和研究开发,从分类与起源、植物学特征与生物学特性、应用价值以及栽培技术等几个方面,对羽扇豆进行了比较详细的介绍。

Efficiency of white lupin in the removal of mercury from contaminated soils: Soil and hydroponic experiments

This study examined the ability of the white lupin to remove mercury （Hg） from a hydroponic system （Hg concentrations 0, 1.25, 2.5, 5 and 10 μmol/L） and from soil in pots and lysimeters （total Hg concentration （19.2 ± 1.9） mg/kg availability 0.07%, and （28.9 ± 0.4） mg/kg availability 0.09%, respectively）, and investigated the accumulation and distribution of Hg in different parts of the plant. White lupin roots efficiently took up Hg, but its translocation to the harvestable parts of the plant was low. The Hg concentration in the seeds posed no risk to human health according to the recommendations of the World Health Organization, but the shoots should not be used as fodder for livestock, at least when unmixed with other fodder crops. The accumulation of Hg in the hydroponically-grown plants was linear over the concentration range tested. The amount of Hg retained in the roots, relative to the shoots, was almost constant irrespective of Hg dose （90%）. In the soil experiments, Hg accumulation increased with exposure time and was the greater in the lysimeter than in the pot experiments. Although Hg removal was the greater in the hydroponic system, revealing the potential of the white lupin to extract Hg, bioaccumulation was the greatest in the lysimeter-grown plants; the latter system more likely reflects the true behaviour of white lupin in the field when Hg availability is a factor that limits Hg removal. The present results suggest that the white lupin could be used in long-term soil reclamation strategies that include the goal of profitable land use in Hg-polluted areas.

Bio-Morphological Characters of Alien Legume Species, Influencing Their Invasion in Natural Plant Communities

Five alien legume species, actively invading in natural plant communities in European part of Russia, were studied—Lupinus polyphyllus Lindl., Galega orientalis Lam., Robinia pseudoacacia L., Amorpha fruticosa L. and Caragana arborescens L. Distribution ranges (considering their invasive status) were mapped. Not a single bio-morphological character to forecast invasion success in natural plant communities within secondary distribution range was found. The data of key value/importance for explaining invasive success of the species studied were obtained. Two hypotheses— Propagule Pressure and Evolution of Invasiveness—were critically analyzed in view of the received data.

温度及基质对羽扇豆种子发芽的影响

通过测定不同温度和基质条件下羽扇豆(Lupinus micranthus Guss.)种子的发芽率、发芽势、生长量以及幼苗生长过程,分析温度和基质对羽扇豆种子萌发的影响。结果表明,温度对种子萌发和幼苗生长影响明显,是羽扇豆种子萌发与幼苗生长最重要的环境因子,15℃最利于获得较高发芽率,25℃最有利于获得高生长量;基质对羽扇豆的最大生长量影响极显著,对发芽始期和发芽势影响显著,对发芽率、发芽末期、发芽时间和平均日生长量影响不显著,最具综合优势的基质是珍珠岩,蛭石最有利于幼苗的生长;温度与基质对发芽率、发芽期指标、发芽势和最大生长量有明显交互作用,温度与基质的最优处理是“15℃+本地黄心土”和“15℃+草炭”。

Analysis of Genetic Difference Between Species in Lupins by AFLP

The genetic difference between species in 18 lupins (Lupinus L .) varieties including L. angus-tifolius L., L . albus L., L. pilosus Murr. was analyzed using AFLP. A total of 462 bands were observed, a-mong of which, 442 (95.7%) were polymorphic, with an average of 110.5 polymorphic bands for each AFLP primer combination. The average genetic diversity index was 0.781 in this study. The genetic difference between species was higher than that of between varieties, the average identification percentage of four AFLP primer combinations was 100% and 84.7% between species and between varieties, respectively. The cluster analysis indicated that 3 species were distinctly distinguished on the dendrogram using UPGMA method.

Carbon Isotope Discrimination is not Correlated with Transpiration Efficiency in Three Cool-Season Grain Legumes(Pulses)

The carbon isotope discrimination （δ^13C） of leaves has been shown to be correlated with the transpiration efficiency of leaves in a wide range of species. This has led to δ^13C being used in breeding programs to select for improved transpiration efficiency. The correlation between δ^13C and transpiration efficiency was determined under well-watered conditions during the vegetative phase in six genotypes of lentil （Lens culinaris Medikus）, six genotypes of chickpea （Cicerarietinum L.） and 10 cultivars of narrow-leafed lupin （Lupinus angustifolius L.）. Biomass （dry matter） accumulation and water use （transpiration） varied among the genotypes in all three species and transpiration efficiency was 40% to 75% higher in the most efficient compared with the least efficient genotypes. However, δ^13C and transpiration efficiency were not significantly correlated in any of the species. This suggests that the δ^13C technique cannot be used in selection for transpiration efficiency in the three grain legumes （pulses） studied.

Identification in Lupin Seed of a Serine- Endopeptidase Activity Cleaving between Twin Arginine Pairs and Causing Limited Proteolysis of Seed Storage Proteins

The occurrence of twin-arginine motifs （-R-R-） in the amino acid sequences of animal pro-proteins frequently defines the cleavage site（s） for their structural/functional maturation. No information is available on the presence and possible biological meaning of these motifs in the seed storage proteins. In this work, a novel endopeptidase activity with cleavage specificity to twin-arginine pairs has been detected in mature dry Lupinus albus seeds. The endopeptidase was tested with a number of endogenous and exogenous protein substrates, which were selected according to the pres- ence of one or more twin-arginine residue motifs in their amino acid sequences. The observed hydrolysis patterns were limited and highly specific. Partial proteolysis led to stable polypeptide fragments that were characterized by 1- and 2-D electrophoresis. Selected polypeptides were submitted to N-terminal amino acid sequencing and mass spectrometry anal- yses, These approaches, supported by bioinformatic analysis of the available sequences, allowed the conclusion that the polypeptide cleavage events had occurred at the peptide bonds comprised between twin-arginine residue pairs with all tested protein substrates. The endopeptidase activity was inhibited by 4-（2-AminoEthyl）Benzene-Sulphonyl Fluoride hy- drochloride （AEBSF）, leupeptin, and serine proteinase protein inhibitors, while it was not affected by pepstatin, trans- EpoxysuccinyI-L-leucylamido（4-guanidino）butane （E64）, and ethylenediaminetetraacetic acid （EDTA）, thus qualifying the Arg-Arg cleaving enzyme as a serine endopeptidase. The structural features of storage proteins from lupin and other legume seeds strongly support the hypothesis that the occurrence of an endopeptidase activity cleaving -R-R- bonds may be functional to facilitate their degradation at germination and possibly generate polypeptide fragments with specific biological activity.