Genetic diversity of Crotalaria germplasm assessed through phylogenetic analysis of EST-SSR markers.

The genetic diversity of the genus Crotalaria is unknown even though many species in this genus are economically valuable. We report the first study in which polymorphic expressed sequence tag-simple sequence repeat (EST-SSR) markers derived from Medicago and soybean were used to assess the genetic diversity of the Crotalaria germplasm collection. This collection consisted of 26 accessions representing 4 morphologically characterized species. Phylogenetic analysis partitioned accessions into 4 main groups generally along species lines and revealed that 2 accessions were incorrectly identified as Crotalaria juncea and Crotalaria spectabilis instead of Crotalaria retusa. Morphological re-examination confirmed that these 2 accessions were misclassified during curation or conservation and were indeed C. retusa. Some amplicons from Crotalaria were sequenced and their sequences showed a high similarity (89% sequence identity) to Medicago truncatula from which the EST-SSR primers were designed; however, the SSRs were completely deleted in Crotalaria. Highly distinguishing markers or more sequences are required to further classify accessions within C. juncea.     

Cloning of dehydrin coding sequences from Brassica juncea and Brassica napus and their low temperature-inducible expression in germinating seeds.

A novel subclass of dehydrin genes, homologous to the Raphanus sativus late embryogenesis-abundant (LEA) protein (RsLEA2) and the Arabidopsis thaliana dehydrin, was isolated from Brassica juncea and Brassica napus, here designated BjDHN1 and BnDHN1, respectively. The cDNA of BjDHN1 and BnDHN1 genes share 100% nucleotide identity. The encoded protein is predicted to consist of 183 amino acid residues (molecular mass of 19.2 kDa and pI of 7.0). It shares 85.3% and 65.4% amino acid sequence identity with the RsLEA2 and Arabidopsis dehydrin, respectively. This Brassica dehydrin also features a "Y(3)SK(2)" plant dehydrin structure. Expression analysis indicated that the Brassica dehydrin gene is expressed at the late stages of developing siliques, suggesting that the gene expression may be inducible by water-deficit. Analysis of gene expression also indicated that in germinating seeds the gene expression was inducible by low temperature. Seed germination under low temperature was compared between B. juncea and B. napus. The results showed that B. juncea seeds germinated faster than B. napus seeds. Expression of Brassica dehydrin gene was also examined as a function of seed germination under low temperature.     

Effect of Concentration and Temperature on Flow Properties of Alyssum homolocarpum Seed Gum Solutions: Assessment of Time Dependency and Thixotropy

Effects of different shear rates (14, 25, and 50 s⁻¹), gum concentrations (3%, 3.5%, and 4%), and temperatures (5–65 °C) on flow properties of Alyssum homolocarpum seed gum solutions were investigated using a rotational viscometer. The experimental data were fitted with three time-dependent rheological models, namely second-order structural kinetic model, Weltman model, and first-order stress decay model with a non-zero stress value. The rate constant and extent of viscosity strongly depended on the shear rate, gum concentration, and temperature. It was found that A. homolocarpum seed gum samples exhibited shear thinning and thixotropic behavior for all concentrations and temperatures. The amount of structural breakdown decreased with shear rate, but it did not have a general trend with concentration and temperature. The extent of thixotropy increased with increasing gum concentration and decreased with increasing temperature and shear rate. In this work, the decay rate constant generally increased with increasing shear rate; however, it did not have any trend with concentration and temperature.     

Feeding and oviposition preference of Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) on several crops

Laboratory and greenhouse experiments were carried out to study food and oviposition preference by Phyllophaga cuyabana (Moser) on different plant species as Cajanus cajan L. (pigeon pea), Crotalaria juncea L. (sun hemp), Crotalaria spectabilis Roth (showy crotalaria), Crotalaria ochroleuca G. Don (slenderleaf rattlebox), Glycine max [L.] Merrill (soybean), Gossypium hirsutum L. (cotton), Helianthus annuus L. (sunflower), Stizolobium aterrimum [Mucuna aterrima] Piper Tracey (velvetbean) and Zea mays L. (mayze). In no-choice experiments, the number of eggs layed in sunflower, C. juncea and soybean was larger compared to cotton. Despite the fact that the adults did not discriminate among plants, in dual-choice test, the proportion of eggs layed and leaf consumption by P. cuyabana adults in soybean were significantly higher than in C. spectabilis. The larval distribution in the soil was at random in multiple-choice, without any trend of preference, but in dual-choice, when soybean was the control, larvae always preferred to feed on its roots. P. cuyabana adults had preference for more suitable hosts and that could stand their offspring survival. This behaviour can be usefully exploited in an integrated management program for this pest.     

Rheological properties of barley β-glucan

Health benefits of cereal β-glucan are linked to its high viscosity. Although viscosity of β-glucan gum solutions has been reported previously, there are conflicting reports about its behavior at elevated temperatures. Therefore, the viscosity behavior of barley β-glucan gum obtained in a pilot plant (PP) or in a laboratory (LAB) was determined at different shear rates (1.29–129 s⁻¹) and temperatures (0.1–75 °C) in this study. Viscosity decrease with temperature was demonstrated for both gums and activation energy E_a was calculated from the Arrhenius equation. None of the fresh gum solutions exhibited thixotropic behavior at ≤1% (w/w) concentration, but the measurement demonstrated that increased shear rate is not applicable to polymer solutions of low viscosity. Information about rheological properties of β-glucan will lead to better understanding of its behavior under physiological and processing conditions.     

Effects of selenium accumulation on reproductive functions in Brassica juncea and Stanleya pinnata

Selenium (Se) is an essential micronutrient for many organisms, but is also a toxin and environmental pollutant at elevated levels. Due to its chemical similarity to sulphur, most plants readily take up and assimilate Se. Se accumulators such as Brassica juncea can accumulate Se between 0.01% and 0.1% of dry weight (DW), and Se hyperaccumulators such as Stanleya pinnata (Brassicaeae) contain between 0.1% and 1.5% DW of Se. While Se accumulation offers the plant a variety of ecological benefits, particularly protection from herbivory, its potential costs are still unexplored. This study examines the effects of plant Se levels on reproductive functions. In B. juncea, Se concentrations >0.05-0.1% caused decreases in biomass, pollen germination, individual seed and total seed weight, number of seeds produced, and seed germination. In S. pinnata there was no negative effect of increased Se concentration on pollen germination. In cross-pollination of B. juncea plants with different Se levels, both the maternal and paternal Se level affected reproduction, but the maternal Se concentration had the most pronounced effect. Interestingly, high-Se maternal plants were most efficiently pollinated by Se-treated paternal plants. These data provide novel insights into the potential reproductive costs of Se accumulation, interactive effects of Se in pollen grains and in the pistil, and the apparent evolution of physiological tolerance mechanisms in hyperaccumulators to avoid reproductive repercussions.     

西藏野生芥菜型油菜构件种群相互关系及其与气候因素的灰色关联度分析

以生物构件理论为基础,运用灰色关联分析技术对西藏野生芥菜型油菜种群构件结构与环境因子的关系进行了研究。结果表明:1)每株角果数、每角果粒数和粒重是产量构成的重要指标,随着每株角果数、每角果粒数和粒重的增大,西藏野生芥菜型油菜的产量明显增加,它们之间的构件因子关联度较大;2)主茎系统是西藏野生芥菜型油菜植株的基础,其间的关联性显示了西藏野生芥菜型油菜植株构件组成的整合作用;3)一级分枝长度、一级分枝角果数、二级分枝数、一级分枝粗度之间有较大的关联度,但与一级分枝发生高度关联度相对较小;4)研究的7个环境因子与西藏野生芥菜型油菜种群的生长关系均较密切,且温度是影响西藏野生芥菜型油菜分布和生命活动相对重要的环境因子,而降水为次要因子。     

Use of Cassia javahikai seed gum and gum-g-polyacrylamide as coagulant aid for the decolorization of textile dye solutions

Investigations were carried out for possible exploitation of Cassia javahikai seeds as potential source of commercial gum for the textile wastewater treatment. Graft copolymerization with acrylamide was done to modify the seed gum for the favorable properties. C. javahikai seed gum, and its copolymer grafted with acrylamide were synthesized in the presence of oxygen using potassium persulphate/ascorbic acid redox system. Both C. javahikai seed gum (CJ) and its grafted-polyacrylamide (CJG), were found to be good working substitutes as coagulant aids in conjunction with PAC, for the decolorization of all the dyes in varying ratios. CJ and CJG alone could effectively decolorize direct dyes (DBR and DO) and in conjunction with a very low dose of PAC could decolorize all the dyes (DBR, DO, ASR, and PBB) to more than 70%. Grafting also increased the decolorizing ability of CJ gum.     

Guar gum as a gelling agent for plant tissue culture media

Summary Guar gum, a galactomannan derived from the endosperms of Cyamposis tetragonoloba, has been successfully used as a sole gelling agent for plant tissue culture media. Its suitability as a gelling agent was demonstrated by using guar gumgelled media for in vitro seed germination of Linum usitatissimum and Brassica juncea, in vitro axillary shoot proliferation in nodal explants of Crataeva nurvala, rooting of regenerated shoots of the same, in vitro androgenesis in anther cultures of Nicotiana tabacum, and somatic embryogenesis in callus cultures of Calliandra tweedii. The media used for these were gelled with either guar gum (2, 3, or 4%) or agar (0.9%). Guar gum-gelled media, like agar media, supported all these morphogenic responses. Rather, axillary shoot proliferation, rhizogenic and embryogenic responses were better on guar gum-gelled media than on agar media.     

Dielectric relaxation in a single tryptophan protein.

Although dielectric relaxation can significantly affect the intrinsic fluorescence properties of a protein, usually it is fast compared to fluorescence timescales and needs to be slowed down by adding viscogens or lowering temperature before its impact on fluorescence can be studied. We report here a remarkable blue shift in fluorescence upon bimolecular quenching in the single-tryptophan thermostable protein Bj2S, the 2S seed albumin from Brassica juncea, at ambient temperature and viscosity. The magnitude of the blue shift ( approximately 5 nm at 50% quenching by acrylamide) is striking in a single-tryptophan protein and is attributed to a slowly relaxing dielectric environment in Bj2S from red edge excitation, steady-state polarization and time-resolved fluorescence experiments. Our results have important implications on interpretation of fluorescence of proteins with highly constrained backbones and in designing model systems for studying slow protein solvation dynamics using Trp fluorescence as the reporter probe.     

Use of xantham gum to suspend large particles during flow cytometric analysis and sorting

In this report we describe the use of xantham gum as a biologically inert material for increasing the viscosity of a suspension of cells or particles during flow cytometric analysis and sorting. A 0.1% concentration of xantham gum in culture medium or saline will increase the viscosity approximately 9-fold. For suspensions of multicellular spheroids 100-400 microns in diameter the measured sedimentation velocity was approximately 9 times slower than that in medium alone. Thus, spheroids of 100 microns diameter remain in suspension in 0.1% xantham gum for 66 min, compared to 7.5 min in culture medium. This allows extended periods of sorting without stirring or agitating the sample suspension. The xantham gum solution is noncytotoxic for periods up to 8 h as measured by clonogenicity assay. Xantham gum has the added advantage that the viscosity is significantly reduced when the solution is subjected to shear stress, such as during flow. This technique should be applicable to extended sorting of suspensions of spheroids, plant cells, and other large particles, as well as for analyzing and sorting single cells for extended periods.     

Characteristics of cadmium accumulation and tolerance in novel Cd-accumulating crops, Avena strigosa and Crotalaria juncea

Characteristics of accumulation and tolerance of cadmium (Cd) in green manure crops were investigated to identify Cd-accumulating crops and to clarify the mechanisms involved in Cd accumulation and tolerance. Seedlings of eight crop species were treated with Cd (1 mg l(-1) or 5 mg l(-1)) in the growing medium for 4 d. Cd concentration in leaves of Avena strigosa Schreb. cv. New-oat, Crotalaria juncea L. and Tagetes erecta L. cv. African-tall was greater than values used to define Cd-hyperaccumulation (>100 mg Cd kg(-1) DW). However, in leaves of T. erecta, lipid peroxidation level increased significantly, and the activities of superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase were depressed by both Cd treatments. By contrast, A. strigosa and C. juncea exhibited high Cd tolerance. Avena strigosa leaves showed higher activities of antioxidative enzymes such as superoxide dismutase and ascorbate peroxidase than those of other species tested. Crotalaria juncea showed higher amounts of total soluble phenolics which, in leaves, were doubled by 5 mg l(-1) Cd treatment. When two Cd-tolerant accumulators (A. strigosa and C. juncea) and the non-accumulator (C. spectabilis) were treated with lower Cd concentrations for 4 weeks, A. strigosa and C. juncea exhibited superior Cd accumulation in the shoots with greater biomass production compared with C. spectabilis. These results indicate that A. strigosa and C. juncea possess the greater potential for Cd accumulation and tolerance than common crops.     

野生鸭儿芹种子休眠特性及破除方法

鸭儿芹种子具有休眠特性,且休眠期长,不经任何处理的种子很难萌发,影响其人工种植。研究了鸭儿芹种子的休眠特性和解除休眠的最佳方法,为我国人工种植野生鸭儿芹提供理论依据。结果表明:TTC法对种子活力的测定表明有活力的种子为(55.33±3.71)%;切破种皮种子与完整种子吸水率在前12 h相差较大,但最终吸水率相差不大,分别达到(70.00±1)%和(68.32±0.32)%,表明种皮并不阻碍种子吸水;种子中存在内源抑制物,其粗提液在较低浓度下即可抑制芹菜种子的萌发;鸭儿芹种子成熟时胚未分化完全,胚率为(28.65±2.488)%,经过低温处理后完成后熟,胚率达到(65.93±3.86)%,萌发率达到100%,因此鸭儿芹种子具有形态生理休眠特性。清水浸种和低温冷藏共同处理可有效解除其休眠,浸种和低温冷藏具有交互效应,浸种36 h、5℃冷藏30d即可解除其休眠,萌发率达到100%,发芽势达到(91.11±0.91)%。已破除休眠的种子适宜其萌发的温度范围扩大(15.0—27.5℃),而且在土壤中也可较好地萌发,萌发率达到(96.67±3.33)%,发芽势达到(71.11±1.93)%。     

Chemical modification of Cassia occidentalis seed gum: carbamoylethylation

The seeds of Cassia occidentalis, an annual weed occurring throughout India, is a rich source of galactomannan gum. The gum derived from seed endosperm can be potentially utilized in a number of industries to replace the conventional gums. With a view to utilize the gum for broader applications, carbamoylethylation of C. occidentalis seed gum was carried out with acrylamide in presence of sodium hydroxide under different reaction conditions. Variables studied were concentration of sodium hydroxide, acrylamide, gum–solvent ratio, reaction time and temperature. The nitrogen content, carboxyl content and total ether content were determined. The optimum condition for preparing carbamoylethyl C. occidentalis seed gum (%N=2.57) comprised concentration of acrylamide (0.070 mol), sodium hydroxide (0.125 mol), C. occidentalis seed gum (0.03 mol) at 30 °C for 3 h. Rheological properties of carbamoylethyl C. occidentalis seed gum solution showed non-Newtonian pseudo-plastic behavior, relatively high viscosity, cold water solubility and solution clarity vis-à-vis unmodified C. occidentalis seed gum.     

Brassicaceous Seed Meals as Soil Amendments to Suppress the Plant-parasitic Nematodes Pratylenchus penetrans and Meloidogyne incognita

Brassicaceous seed meals are the residual materials remaining after the extraction of oil from seeds; these seed meals contain glucosinolates that potentially degrade to nematotoxic compounds upon incorporation into soil. This study compared the nematode-suppressive ability of four seed meals obtained from Brassica juncea 'Pacific Gold', B. napus 'Dwarf Essex' and 'Sunrise', and Sinapis alba 'IdaGold', against mixed stages of Pratylenchus penetrans and Meloidogyne incognita second-stage juveniles (J2). The brassicaceous seed meals were applied to soil in laboratory assays at rates ranging from 0.5 to 10.0% dry w/w with a nonamended control included. Nematode mortality was assessed after 3 days of exposure and calculated as percentage reduction compared to a nonamended control. Across seed meals, M. incognita J2 were more sensitive to the brassicaceous seed meals compared to mixed stages of P. penetrans. Brassica juncea was the most nematode-suppressive seed meal with rates as low as 0.06% resulting in > 90% suppression of both plant-parasitic nematodes. In general B. napus 'Sunrise' was the least nematode-suppressive seed meal. Intermediate were the seed meals of S. alba and B. napus 'Dwarf Essex'; 90% suppression was achieved at 1.0% and 5.0% S. alba and 0.25% and 2.5% B. napus 'Dwarf Essex', for M. incognita and P. penetrans, respectively. For B. juncea, seed meal glucosinolate-degradation products appeared to be responsible for nematode suppression; deactivated seed meal (wetted and heated at 70 °C for 48 hr) did not result in similar P. penetrans suppression compared to active seed meal. Sinapis alba seed meal particle size also played a role in nematode suppression with ground meal resulting in 93% suppression of P. penetrans compared with 37 to 46% suppression by pelletized S. alba seed meal. This study demonstrates that all seed meals are not equally suppressive to nematodes and that care should be taken when selecting a source of brassicaceous seed meal for plant-parasitic nematode management.     

Recruitment of alkaloid-specific homospermidine synthase (HSS) from ubiquitous deoxyhypusine synthase: Does Crotalaria possess a functional HSS that still has DHS activity?

Quinolizidine alkaloids are the most prominent group of alkaloids occurring in legumes, except for many members of the tribe Crotalarieae that accumulate pyrrolizidine alkaloids (PAs). To study the evolution of PA biosynthesis as a typical pathway of plant secondary metabolism in this tribe, we have searched for a cDNA coding for homospermidine synthase (HSS), the enzyme catalyzing the first specific step in this biosynthesis. HSS was shown to have been recruited from deoxyhypusine synthase (DHS) by independent gene duplication in several different angiosperm lineages during evolution. Except for a cDNA sequence coding for the DHS of Crotalaria retusa, no data is available concerning the origin of PA biosynthesis within this tribe of the Fabaceae. In addition to several pseudogenes, we have identified one functional DHS in C. scassellatii and two in C. juncea. Despite C. juncea plants under study being devoid of PAs, we have found that the two sequences of C. juncea are different with respect to their genomic organization, their tissue-specific expression, and their biochemical activities. Supported by the branching pattern of a maximum likelihood analysis of these sequences, they have been classified as "class 1" and "class 2" DHS. It remains open whether the duplicated DHS belonging to class 2 is involved in the biosynthesis of PAs.     

Isolation,Purification and Partial Characterization of <Emphasis Type="Italic">Crotalaria pallida</Emphasis> Aiton Seed Proteins

Crotalaria pallida Aiton (Smooth rattlebox in English) is widely and wildly distributed in India. The seed of this plant is a valuable source of non-traditional proteins (about 22%) but attention was never been paid to explore the protein content. Chemical investigation has been conducted on Crotalaria pallida seeds (de-oiled) and proteins have been extracted in aqueous solution with different pHs or various concentrations of NaCl, KCl, Na₂SO₃ and CaCl₂·2H₂O at pH 7.0. The present study includes isolation, purification, and fractionation of seed protein along with its amino acid composition, molecular weight determination and surface topographies. Multiple polypeptide bands have been identified in the range of 16.5–61.6 kDa. The overall study confirms the seeds of this plant as an important source of unexplored protein.     

Herbivory by hares as a threat to the native brooms

Adult mortality, seed production, and seedling establishment of two species of New Zealand broom (Carmichaelia juncea and C. vexillata) were studied in exclosure trials to determine the level of threat posed by herbivory by introduced mammals. While no effect on mortality was observed for either species, herbivory by hares drastically reduced seed production and subsequent seedling establishment in C. juncea. C. vexillata seemed less vulnerable to herbivore damage due to its plant architecture, as well as the timing and intensity of the herbivore impact. The results of this trial suggest that species characteristics and the dynamics of herbivore impacts need to be considered in planning targeted herbivore control.     

New Culture Medium to Xanthan Production by <Emphasis Type="Italic">Xanthomonas campestris</Emphasis> pv<Emphasis Type="Italic">. campestris</Emphasis>

Xanthan is a important biopolymer for commercial purpose and it is produced in two stages by Xanthomonas campestris. In the first one, the bacterium is cultivated in the complex medium enriched in nitrogen and the biomass produced is used as inoculum for the next stage in which the gum is produced in another medium. In this work a new medium for the first stage is proposed in place of currently used YM medium. Different formulated growth media were studied and the correspondent biomass produced was analysed as inoculum for the second stage. The inoculum and gum were produced by batch process in shaker at 27°C in pH 6.0 and at 30°C in pH 7.0, respectively. The gum was precipitated with ethanol (3:1 v/v). The dryed biomass and xathan gum produced were determined by drying in oven at 105 and 40°C, respectively. The viscosity of the fermentation broth and 1% gum solution in water were determined in Brookfield viscometer. The formulated medium presented the increase in gum production (30%), broth (136%) and 1% gum solution viscosity (60%) compared to YM, besides the inferior cost. The results showed the importance of the quality of the inoculum from the first stage of the culture which influenced on the gum viscosity in the second stage.     

Nodulation of Crotalaria podocarpa DC. by Methylobacterium nodulans displays very unusual features

Crotalaria are plants of the Fabaceae family whose nodulation characteristics have been little explored despite the recent discovery of their unexpected ability to be efficiently nodulated in symbiosis with bacteria of the genus Methylobacterium. It has been shown that methylotrophy plays a key role in this unusual symbiotic system, as it is expressed within the nodule and as non-methylotroph mutants had a depleting effect on plant growth response. Within the nodule, Methylobacterium is thus able to obtain carbon both from host plant photosynthesis and from methylotrophy. In this context, the aim of the present study was to show the histological and cytological impacts of both symbiotic and methylotrophic metabolism within Crotalaria podocarpa nodules. It was established that if Crotalaria nodules are multilobed, each lobe has the morphology of indeterminate nodules but with a different anatomy; that is, without root hair infection or infection threads. In the fixation zone, bacteroids display a spherical shape and there is no uninfected cell. Crotalaria nodulation by Methylobacterium displayed some very unusual characteristics such as starch storage within bacteroid-filled cells of the fixation zone and also the complete lysis of apical nodular tissues (where bacteria have a free-living shape and express methylotrophy). This lysis could possibly reflect the bacterial degradation of plant wall pectins through bacterial pectin methyl esterases, thus producing methanol as a substrate, allowing bacterial multiplication before release from the nodule.